无题
1 | title: 移动互联网技术 |
安卓复习
实验一
请结合android的体系结构说明，为什么Android选择Java作为上层应用的开发语言。
四层结构
- 应用层：自带应用，拨号应用，短信应用，浏览器等
- 应用框架层：为开发者提供了大量的API
- 系统运行库层
- Libraries类库：提供SQLite、Media等功能
- Android Runtime
- Core Libraries 核心库：提供Java编程的核心库
- Davlik 虚拟机：用来执行Android程序的。每一个Android应用程序都是在一个独立的Davlik虚拟机实例中执行的。
- Linux内核层：内存管理，进程管理，网络协议，以及驱动模型等核心服务
原因
广泛的生态系统，Java是一种广泛使用的语言，有庞大而成熟的开发者社区和丰富的第三方库支持。开发人员可以更快速地构建和扩展Android应用程序，解决问题时可以利用大量开源资源。
跨平台，通过JVM，安卓应用程序可以再不同硬件和操作系统上运行，便于开发者更高效的开发并将应用程序发布到不同设备上
性能优化，安卓平台通过引入JIT编译器，AOT编译器等技术来提升java应用程序的性能，这些优化措施使java在安卓平台上可以提供高效的运行和响应能力
良好的安全性，Java具有严格的安全性措施，例如内存管理，异常处理和访问控制等机制，为移动应用程序提供可靠的安全保护，防止恶意代码和漏洞的利用
对新手友好，Java语言相对于其他语言来说，相对容易学习和理解，采用简洁明了的语法，提供强大的面向对象编程功能，且拥有丰富的文档和教k程资源，使得初学者和新手开发者可以更容易地进入Android应用开发领域。
请说明Android Studio和 Android SDK的关系。
- Android Studio是安卓应用开发工具
- Android SDK是一个开发包，提供开发工具给开发者开发安卓
- Android Studio内置了Android SDK
AVD Manager,SDK Mannager,DDMS分别是干什么的？
- AVD Manager：创建和管理Android虚拟设备的工具
- SDK Mannager：开发工具包中的一个核心组件，用于管理和更新Android SDK的各种组件
- DDMS：监控和调试Android设备或模拟器上运行的应用程序的调试工具
请结合HelloWorld程序说明Android中是如何基于MVC模式进行开发的？
实验二
除了课堂上介绍的设置的监听器的方法，还有哪些办法实现按钮的响应？
增加两个按钮（prev，next）实现问题的遍历。
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37public class MainActivity extends AppCompatActivity {
private TextView mQuestion;
private int mCurrentIndex = 0;
public int[] mQuestionBank = new int[]{
R.string.question_australia,
R.string.question_oceans,
R.string.question_mideast,
R.string.question_africa,
R.string.question_americas,
R.string.question_asia,
};
private Button mBtnPrev;
private Button mMBtnNext;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mQuestion = findViewById(R.id.question_text);
mQuestion.setText(mQuestionBank[mCurrentIndex]);
mBtnPrev = findViewById(R.id.btnPrev);
mBtnPrev.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
mCurrentIndex = (mCurrentIndex - 1 + mQuestionBank.length) % mQuestionBank.length;
mQuestion.setText(mQuestionBank[mCurrentIndex]);
}
});
mMBtnNext = findViewById(R.id.btnNext);
mMBtnNext.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
mCurrentIndex = (mCurrentIndex + 1) % mQuestionBank.length;
mQuestion.setText(mQuestionBank[mCurrentIndex]);
}
});
}
}问题描述已经分离在资源文件中，如何将answer也分离在资源文件中？
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27public class Question {
private int mTextId;
private int mAnswerId;
public Question(int textId, int answerId) {
mTextId = textId;
mAnswerId = answerId;
}
public int getTextId() {
return mTextId;
}
public void setTextId(int textId) {
mTextId = textId;
}
public int getAnswerId() {
return mAnswerId;
}
public void setAnswerId(int answerId) {
mAnswerId = answerId;
}
public String toString() {
return "Question{" +
"mTextId=" + mTextId +
", mAnswerId=" + mAnswerId +
'}';
}
}1
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32public Question[] mQuestionBank = new Question[]{
new Question(R.string.question_australia,R.string.false_answer),
new Question(R.string.question_oceans,R.string.true_answer),
new Question(R.string.question_mideast,R.string.true_answer),
new Question(R.string.question_africa,R.string.true_answer),
new Question(R.string.question_americas,R.string.true_answer),
new Question(R.string.question_asia,R.string.true_answer),
};
//选择True
mMBtnTrue = findViewById(R.id.btnTrue);
mMBtnTrue.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
if (mQuestionBank[mCurrentIndex].getAnswerId() == R.string.true_answer) {
Toast.makeText(MainActivity.this, R.string.correct_toast, Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(MainActivity.this, R.string.incorrect_toast, Toast.LENGTH_SHORT).show();
}
}
});
//选择False
mMMBtnFalse = findViewById(R.id.btnFalse);
mMMBtnFalse.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
if (mQuestionBank[mCurrentIndex].getAnswerId() == R.string.false_answer) {
Toast.makeText(MainActivity.this, R.string.correct_toast, Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(MainActivity.this, R.string.incorrect_toast, Toast.LENGTH_SHORT).show();
}
}
});如果要增加新的问题及其答案，是否需要修改Java代码？能否不修改Java代码，仅修改资源文件就实现增加新的问题。提示：Array类型的资源.
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16<string-array name="questions">
<item>Canberra is the capital of Australia.</item>
<item>The Pacific Ocean is larger than the Atlantic Ocean.</item>
<item>The Suez Canal connects the Red Sea and the Indian Ocean.</item>
<item>The source of the Nile River is in Egypt.</item>
<item>The Amazon River is the longest river in the Americas.</item>
<item>Lake Baikal is the world\'s oldest and deepest freshwater lake.</item>
</string-array>
<string-array name="answers">
<item>false</item>
<item>true</item>
<item>true</item>
<item>true</item>
<item>true</item>
<item>true</item>
</string-array>1
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19public class Question {
private String mQuestionText;
private String mAnswerText;
public Question(String questionText, String answerText) {
mQuestionText = questionText;
mAnswerText = answerText;
}
public String getQuestionText() {
return mQuestionText;
}
public void setQuestionText(String questionText) {
mQuestionText = questionText;
}
public String getAnswerText() {
return mAnswerText;
}
public void setAnswerText(String answerText) {
mAnswerText = answerText;
}1
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protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mQuestion = findViewById(R.id.question_text);
String[] questions = getResources().getStringArray(R.array.questions);
String[] answers = getResources().getStringArray(R.array.answers);
Question[] mQuestionBank = new Question[questions.length];
for (int i = 0; i < questions.length; i++) {
mQuestionBank[i] = new Question(questions[i], answers[i]);
}
mQuestion.setText(mQuestionBank[mCurrentIndex].getQuestionText());
//上一题
mBtnPrev = findViewById(R.id.btnPrev);
mBtnPrev.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
mCurrentIndex = (mCurrentIndex - 1 + mQuestionBank.length) % mQuestionBank.length;
mQuestion.setText(mQuestionBank[mCurrentIndex].getQuestionText());
}
});用户答完某题后，禁掉对应题目的True和False作答按钮，即，一个题目只允许作答一次；
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69public int[] mAnswerFlag = new int[mQuestionBank.length];//0表示未回答，1表示回答正确，2表示回答错误
//上一题
mBtnPrev = findViewById(R.id.btnPrev);
mBtnPrev.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
mCurrentIndex = (mCurrentIndex - 1 + mQuestionBank.length) % mQuestionBank.length;
mQuestion.setText(mQuestionBank[mCurrentIndex].getTextId());
if (mAnswerFlag[mCurrentIndex] == 0) {
mMBtnTrue.setEnabled(true);
mMMBtnFalse.setEnabled(true);
} else {
mMBtnTrue.setEnabled(false);
mMMBtnFalse.setEnabled(false);
}
}
});
//下一题
mMBtnNext = findViewById(R.id.btnNext);
mMBtnNext.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
mCurrentIndex = (mCurrentIndex + 1) % mQuestionBank.length;
mQuestion.setText(mQuestionBank[mCurrentIndex].getTextId());
if (mAnswerFlag[mCurrentIndex] == 0) {
mMBtnTrue.setEnabled(true);
mMMBtnFalse.setEnabled(true);
} else {
mMBtnTrue.setEnabled(false);
mMMBtnFalse.setEnabled(false);
}
}
});
//选择True
mMBtnTrue = findViewById(R.id.btnTrue);
mMBtnTrue.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
if (mQuestionBank[mCurrentIndex].getAnswerId() == R.string.true_answer) {
mAnswerFlag[mCurrentIndex] = 1;
mMBtnTrue.setEnabled(false);
mMMBtnFalse.setEnabled(false);
Toast.makeText(MainActivity.this, R.string.correct_toast, Toast.LENGTH_SHORT).show();
} else {
mAnswerFlag[mCurrentIndex] = 2;
mMBtnTrue.setEnabled(false);
mMMBtnFalse.setEnabled(false);
Toast.makeText(MainActivity.this, R.string.incorrect_toast, Toast.LENGTH_SHORT).show();
}
}
});
//选择False
mMMBtnFalse = findViewById(R.id.btnFalse);
mMMBtnFalse.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
if (mQuestionBank[mCurrentIndex].getAnswerId() == R.string.false_answer) {
mAnswerFlag[mCurrentIndex] = 1;
mMMBtnFalse.setEnabled(false);
mMBtnTrue.setEnabled(false);
Toast.makeText(MainActivity.this, R.string.correct_toast, Toast.LENGTH_SHORT).show();
} else {
mAnswerFlag[mCurrentIndex] = 2;
mMMBtnFalse.setEnabled(false);
mMBtnTrue.setEnabled(false);
Toast.makeText(MainActivity.this, R.string.incorrect_toast, Toast.LENGTH_SHORT).show();
}
}
});用户答完全部的题目后，toast消息提示答对题目的百分比评分；
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47int count = 0;//记录回答正确的题目数
//选择True
mMBtnTrue = findViewById(R.id.btnTrue);
mMBtnTrue.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
if (mQuestionBank[mCurrentIndex].getAnswerId() == R.string.true_answer) {
count++;
mAnswerFlag[mCurrentIndex] = 1;
mMBtnTrue.setEnabled(false);
mMMBtnFalse.setEnabled(false);
Toast.makeText(MainActivity.this, R.string.correct_toast, Toast.LENGTH_SHORT).show();
} else {
mAnswerFlag[mCurrentIndex] = 2;
mMBtnTrue.setEnabled(false);
mMMBtnFalse.setEnabled(false);
Toast.makeText(MainActivity.this, R.string.incorrect_toast, Toast.LENGTH_SHORT).show();
}
if(mCurrentIndex==mQuestionBank.length-1){
Double res=(count/(mQuestionBank.length*1.0))*100;
Toast.makeText(MainActivity.this, "正确率为"+res+"%", Toast.LENGTH_SHORT).show();
}
}
});
//选择False
mMMBtnFalse = findViewById(R.id.btnFalse);
mMMBtnFalse.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
if (mQuestionBank[mCurrentIndex].getAnswerId() == R.string.false_answer) {
count++;
mAnswerFlag[mCurrentIndex] = 1;
mMMBtnFalse.setEnabled(false);
mMBtnTrue.setEnabled(false);
Toast.makeText(MainActivity.this, R.string.correct_toast, Toast.LENGTH_SHORT).show();
} else {
mAnswerFlag[mCurrentIndex] = 2;
mMMBtnFalse.setEnabled(false);
mMBtnTrue.setEnabled(false);
Toast.makeText(MainActivity.this, R.string.incorrect_toast, Toast.LENGTH_SHORT).show();
}
if(mCurrentIndex==mQuestionBank.length-1){
Double res=(count/(mQuestionBank.length*1.0))*100;
Toast.makeText(MainActivity.this, "正确率为"+res+"%", Toast.LENGTH_SHORT).show();
}
}
});
实验三
请给MiniQuiz增加一个Activity，在这个新增的Activity提示答案；
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25<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:gravity="center"
tools:context=".CheatActivity">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="题目"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="你确定要提示答案吗？"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="答案"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="提示答案"/>
</LinearLayout>1
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38mMBtnCheat = findViewById(R.id.btnCheat);
mMBtnCheat.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent intent = new Intent(MainActivity.this, CheatActivity.class);
Bundle bundle = new Bundle();
bundle.putString("question", getResources().getString(mQuestionBank[mCurrentIndex].getTextId()));
bundle.putString("answer", getResources().getString(mQuestionBank[mCurrentIndex].getAnswerId()));
intent.putExtras(bundle);
startActivity(intent);
}
});
}
public class CheatActivity extends AppCompatActivity {
private TextView mQuestionCheat;
private Button mBtnShowAnswer;
private TextView mMAnswerCheat;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_cheat);
Bundle bundle = getIntent().getExtras();
String question = bundle.getString("question");
String answer = bundle.getString("answer");
mQuestionCheat = findViewById(R.id.question_cheat);
mQuestionCheat.setText(question);
mMAnswerCheat = findViewById(R.id.answer_cheat);
mBtnShowAnswer = findViewById(R.id.show_answer_button);
mBtnShowAnswer.setOnClickListener(view -> {
mMAnswerCheat.setText(answer);
Toast.makeText(this, "Cheat is wrong", Toast.LENGTH_SHORT).show();
Intent intent = new Intent(CheatActivity.this, MainActivity.class);
startActivity(intent);
});
}
}再新增一个Activty，答完最后一个题目的时候，提示用户一共回答正确和错误的汇总情况，以及使用了提示答案的情况；在这个新增的Acity中共用户选择“退出程序”或者“重新开始答题”。
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60//点击提示答案返回原界面回传作弊次数
//CheatActivity
public class CheatActivity extends AppCompatActivity {
private TextView mQuestionCheat;
private Button mBtnShowAnswer;
private TextView mMAnswerCheat;
private Button mMBtnBack;
private int isCheated = 0;//0表示未作弊，1表示作弊
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_cheat);
Bundle bundle = getIntent().getExtras();
int mCurrentIndex = bundle.getInt("mCurrentIndex");
mQuestionCheat = findViewById(R.id.question_cheat);
mQuestionCheat.setText(MainActivity.mQuestionBank[mCurrentIndex].getTextId());
mMAnswerCheat = findViewById(R.id.answer_cheat);
mBtnShowAnswer = findViewById(R.id.show_answer_button);
mBtnShowAnswer.setOnClickListener(view -> {
isCheated = 1;
mMAnswerCheat.setText(MainActivity.mQuestionBank[mCurrentIndex].getAnswerId());
Toast.makeText(this, "Cheat is wrong", Toast.LENGTH_SHORT).show();
});
//回传是否作弊
mMBtnBack = findViewById(R.id.btn_cheat_back);
mMBtnBack.setOnClickListener(view -> {
Intent intent = new Intent();
Bundle bundle1 = new Bundle();
bundle1.putInt("isCheated", isCheated);
intent.putExtras(bundle1);
setResult(Activity.RESULT_OK, intent);
finish();
});
}
}
//MainActivity
private ActivityResultLauncher<Intent> mRegister;
private int[] isCheated = new int[mQuestionBank.length];//0表示未作弊，1表示作弊
private int mCheatCount=0;
mRegister = registerForActivityResult(new ActivityResultContracts.StartActivityForResult(), result -> {
if(result!=null){
Intent intent=result.getData();
if(intent!=null && result.getResultCode()== Activity.RESULT_OK){
Bundle bundle=intent.getExtras();
//是否作弊
isCheated[mCurrentIndex] = bundle.getInt("isCheated");
}
}
});
mMBtnCheat = findViewById(R.id.btnCheat);
mMBtnCheat.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent intent = new Intent(MainActivity.this, CheatActivity.class);
Bundle bundle = new Bundle();
bundle.putInt("mCurrentIndex", mCurrentIndex);
intent.putExtras(bundle);
mRegister.launch(intent);
}
});1
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40<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:orientation="vertical"
tools:context=".SummaryActivity">
<TextView
android:id="@+id/questionRes_summary"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="24dp" />
<TextView
android:id="@+id/cheatCount_summary"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="24dp" />
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button
android:id="@+id/btnQuit"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Quit" />
<Button
android:id="@+id/btnRestart"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Restart" />
</LinearLayout>
</LinearLayout>1
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14if(mCurrentIndex==mQuestionBank.length-1){
Double res=(count/(mQuestionBank.length*1.0))*100;
Intent intent=new Intent(MainActivity.this,SummaryActivity.class);
Bundle bundle=new Bundle();
bundle.putInt("count",count);
bundle.putDouble("res",res);
for (int i = 0; i < isCheated.length; i++) {
if(isCheated[i]==1){
mCheatCount++;
}
}
bundle.putInt("cheatCount",mCheatCount);
intent.putExtras(bundle);
startActivity(intent);1
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32public class SummaryActivity extends AppCompatActivity {
private TextView mQuestionRes;
private TextView mCheatSummary;
private Button mMBtnQuit;
private Button mMMBtnRestart;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_summary);
Bundle bundle = getIntent().getExtras();
int count = bundle.getInt("count");
Double res=bundle.getDouble("res");
int cheatCount = bundle.getInt("cheatCount");
mQuestionRes = findViewById(R.id.questionRes_summary);
mQuestionRes.setText("回答正确的题目数为："+count+","+"回答错误的题目数为"+(MainActivity.mQuestionBank.length-count)+"\n"+"正确率为："+res+"%,"+"错误率为："+(100-res)+"%");
mCheatSummary = findViewById(R.id.cheatCount_summary);
mCheatSummary.setText("作弊次数为："+cheatCount);
mMBtnQuit = findViewById(R.id.btnQuit);
mMBtnQuit.setOnClickListener(view -> {
Intent home=new Intent(Intent.ACTION_MAIN);
home.addCategory(Intent.CATEGORY_HOME);
startActivity(home);
});
mMMBtnRestart = findViewById(R.id.btnRestart);
mMMBtnRestart.setOnClickListener(view -> {
Intent intent = new Intent(SummaryActivity.this, MainActivity.class);
startActivity(intent);
});
}
}在整个运行过程中，请使用Log显示Activity生命周期状态变化，并在实验报告中分析其状态变化的条件和原因。
一个Activity正常启动时，会按顺序执行onCreate->onStart->onResume,然后这个Activity is running，就可以和用户交互了
当Another activity comes in front of the activity时，即跳转到另外一个界面，执行onPause，原界面不可见了,onStop
当在新的界面中按返回按钮，则会按顺序执行onStop->onRestart->onStart->onResume,返回原界面
如果在跳转新界面过程中原界面还未来得及完全消失按返回键，则会按顺序执行onPause->onResume,此时原界面Activity is running
如果其他应用需要内存，退在后台运行的应用将被系统杀掉，在点到原界面重新进来时，会按顺序执行onStop->onCreate
onCreate:创建活动。把页面布局加载进内存，进入了初始状态。
onStart:开始活动。把活动页面显示在屏幕上，进入了就绪状态。
onResume:恢复活动。活动页面进入活跃状态，能够与用户正常交互，例如允许响应用户的点击动作、允许用户输入文字等等。
onPause:暂停活动。页面进入暂停状态，无法与用户正常交互。
onStop:停止活动。页面将不在屏幕上显示。
onDestroy:销毁活动。回收活动占用的系统资源，把页面从内存中清除。
onRestart:重启活动。重新加载内存中的页面数据。
onNewlntent:重用已有的活动实例。
4.在以上程序运行的过程中，进行横屏和竖屏的切换，要求，无论程序在什么时候切换，都可以正确运行。
为了避免横竖屏切换时重新加载界面的情况，Android设计了一种配置变更机制，在指定的环境配置发生变更之时，无需重启活动页面，只需执行特定的变更行为。该机制的实现过程分为两步：
修改AndroidManifest,xml,给activity节点增加android:configChanges属性
configChanges属性的取值 说明 orientation 屏幕方向发生改变 screenLayout 屏幕的显示发生改变，例如在全屏和分屏之间切换 screenSize 屏幕大小发生改变，例如在竖屏与横屏之间切换 keyboard 键盘发生改变，例如使用了外部键盘 keyboardHidden 软键盘弹出或隐藏 navigation 导航方式发生改变，例如采用了轨迹球导航 fontScale 字体比例发生改变，例如在系统设置中调整默认字体 locale 设备的本地位置发生改变，例如切换了系统语言 uiMode 用户界面的模式发生改变，例如开启了夜间模式 修改活动页面的Java代码，重写活动的onConfigurationChanged方法，补充对应的代码处理逻辑。
1 | <activity |
实验四
实现CiriminalIntent的Fragment的竖屏界面
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10//activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/fragment_container"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
</FrameLayout>1
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35//fragment_crime.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_margin="16dp"
android:orientation="vertical"
tools:context=".CrimeFragment">
<TextView
style="?android:listSeparatorTextViewStyle"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="标题" />
<EditText
android:id="@+id/crime_title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="请输入标题"/>
<TextView
style="?android:listSeparatorTextViewStyle"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="细节" />
<Button
android:id="@+id/crime_date"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="选择日期" />
<CheckBox
android:id="@+id/crime_solved"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="解决了" />
</LinearLayout>1
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55//CrimeFragment
public class CrimeFragment extends Fragment {
private Crime mCrime;
private TextView mTvTitle;
private CheckBox mChkSolved;
private Button mBtnDate;
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
public CrimeFragment() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment CrimeFragment.
*/
// TODO: Rename and change types and number of parameters
public static CrimeFragment newInstance(String param1, String param2) {
CrimeFragment fragment = new CrimeFragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
mCrime = new Crime();
}
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_crime, container, false);
//todo 对view做一些设置
mTvTitle = v.findViewById(R.id.crime_title);
mChkSolved = v.findViewById(R.id.crime_solved);
mBtnDate = v.findViewById(R.id.crime_date);
mTvTitle.setText(mCrime.getId().toString());
mBtnDate.setText(mCrime.getDate().toString());
mChkSolved.setChecked(mCrime.isSolved());
return v;
}
}1
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14//MainActivity
public class MainActivity extends AppCompatActivity {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
FragmentManager fm = getSupportFragmentManager();
Fragment fragment = fm.findFragmentById(R.id.fragment_container);
if (fragment == null) {
fragment = new CrimeFragment();
fm.beginTransaction().add(R.id.fragment_container, fragment).commit();
}
}
}实现CiriminalIntent的Fragment的横屏界面
在res中新建目录layout-land目录，创建与竖屏布局文件同名的文件fragment_crime.xml
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35<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_margin="16dp"
android:orientation="horizontal"
tools:context=".CrimeFragment">
<!-- TODO: Update blank fragment layout -->
<TextView
style="?android:listSeparatorTextViewStyle"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="标题" />
<EditText
android:id="@+id/crime_title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="请输入标题"/>
<TextView
style="?android:listSeparatorTextViewStyle"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="细节" />
<Button
android:id="@+id/crime_date"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="选择日期" />
<CheckBox
android:id="@+id/crime_solved"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="解决了" />
</LinearLayout>在Activity中加载一个Fragment的基本流程
1
使用Fragment设计UI有哪些好处？
实验五
实现一个班级名单的列表视图，每个列表项包含：个人照片，学号和姓名，电话；
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12//MainActivity
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<FrameLayout
android:id="@+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</LinearLayout>1
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94//StudentFragment
public class StuFragment extends Fragment {
private List<Student> mStudentList=new ArrayList<>();
String[] ids = new String[]{"210107101", "210107102", "210107103", "210107104", "210107105", "210107106"};
String[] names = new String[]{"张三", "李四", "王二", "赵六", "小红", "小明"};
String[] phones = new String[]{"1976090901", "1976090902", "1976090903", "1976090904", "1976090905", "1976090906"};
int[] images = new int[]{R.drawable.aa, R.drawable.bb, R.drawable.cc, R.drawable.dd, R.drawable.ee, R.drawable.ff,R.drawable.gg,R.drawable.hh,R.drawable.ii,R.drawable.jj};
private TextView mStuId;
private TextView mMStuName;
private TextView mMStuPhone;
private RecyclerView mRecyclerView;
private StuAdapter mStuAdapter;
private Button mBtnAdd;
private ImageView mMStuImg;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view=inflater.inflate(R.layout.fragment_stu, container, false);
mMStuImg = view.findViewById(R.id.img_stu);
//选择随机头像
final int[] random={0};
mMStuImg.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
random[0]=new Random().nextInt(10);
mMStuImg.setImageResource(images[random[0]]);
}
});
mStuId = view.findViewById(R.id.stu_id);
mMStuName = view.findViewById(R.id.stu_name);
mMStuPhone = view.findViewById(R.id.stu_phone);
mBtnAdd = view.findViewById(R.id.btn_add);
mBtnAdd.setOnClickListener(v->{
String editId=new String(mStuId.getText().toString());
String editName=new String(mMStuName.getText().toString());
String editPhone=new String(mMStuPhone.getText().toString());
Student editStudent=new Student(random[0],editId,editName,editPhone);
mStudentList.add(editStudent);
mStuId.setText("");
mMStuName.setText("");
mMStuPhone.setText("");
mStuAdapter.notifyDataSetChanged();
});
mRecyclerView = view.findViewById(R.id.recyclerview);
mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
mStuAdapter = new StuAdapter();
mRecyclerView.setAdapter(mStuAdapter);
for (int i = 0; i < 6; i++) {
Student student = new Student(i, ids[i], names[i], phones[i]);
mStudentList.add(student);
}
return view;
}
private class StuAdapter extends RecyclerView.Adapter<StuHolder>{
public StuHolder onCreateViewHolder( ViewGroup parent, int viewType) {
View view=View.inflate(getContext(),R.layout.item,null);
return new StuHolder(view);
}
public void onBindViewHolder( StuHolder holder, int position) {
Student student = mStudentList.get(position);
holder.mImgView.setImageResource(images[student.getImgId()]);
holder.mItemId.setText(student.getId());
holder.mMItemName.setText(student.getName());
holder.mMItemPhone.setText(student.getPhone());
holder.mBtnDel.setOnClickListener(v-> {
mStudentList.remove(position);
mStuAdapter.notifyDataSetChanged();
});
}
public int getItemCount() {
return mStudentList.size();
}
}
public class StuHolder extends RecyclerView.ViewHolder{
private final TextView mItemId;
private final TextView mMItemName;
private final TextView mMItemPhone;
private final Button mBtnDel;
private final ImageView mImgView;
public StuHolder( View itemView) {
super(itemView);
mImgView = itemView.findViewById(R.id.item_img);
mItemId = (TextView)itemView.findViewById(R.id.item_id);
mMItemName = (TextView)itemView.findViewById(R.id.item_name);
mMItemPhone = (TextView)itemView.findViewById(R.id.item_phone);
mBtnDel = (Button)itemView.findViewById(R.id.btn_del);
}
}
}1
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69//fragment_stu.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
android:orientation="vertical"
>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="105dp"
android:orientation="vertical">
<EditText
android:id="@+id/stu_id"
android:layout_width="wrap_content"
android:layout_height="35dp"
android:ems="10"
android:hint="请输入学号"
android:inputType="text"
android:textSize="13dp"/>
<EditText
android:id="@+id/stu_name"
android:layout_width="wrap_content"
android:layout_height="35dp"
android:ems="10"
android:hint="请输入姓名"
android:inputType="text"
android:textSize="13dp"/>
<EditText
android:id="@+id/stu_phone"
android:layout_width="wrap_content"
android:layout_height="35dp"
android:ems="10"
android:hint="请输入电话"
android:inputType="text"
android:textSize="13dp"/>
</LinearLayout>
<!-- TODO: Update blank fragment layout -->
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="105dp"
android:orientation="vertical">
<ImageView
android:id="@+id/img_stu"
android:layout_width="155dp"
android:layout_height="105dp"
android:src="@drawable/aa" />
</LinearLayout>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="80dp"
android:orientation="vertical"
android:gravity="center">
<Button
android:id="@+id/btn_add"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="12dp"
android:text="添加"/>
</LinearLayout>
</LinearLayout>
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recyclerview"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>1
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45//item.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ImageView
android:id="@+id/item_img"
android:layout_width="75dp"
android:layout_height="75dp"
android:src="@drawable/aa" />
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="75dp"
android:orientation="vertical">
<TextView
android:id="@+id/item_id"
android:layout_width="250dp"
android:layout_height="25dp"
android:text="TextView"
android:textSize="15dp" />
<TextView
android:id="@+id/item_name"
android:layout_width="250dp"
android:layout_height="25dp"
android:text="TextView"
android:textSize="15dp" />
<TextView
android:id="@+id/item_phone"
android:layout_width="250dp"
android:layout_height="25dp"
android:text="TextView"
android:textSize="15dp" />
</LinearLayout>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="75dp"
android:orientation="vertical"
android:gravity="center"
>
<Button
android:id="@+id/btn_del"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="删除" />
</LinearLayout>
</LinearLayout>可以删除列表项，添加列表项；
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17//删除
holder.mBtnDel.setOnClickListener(v-> {
mStudentList.remove(position);
mStuAdapter.notifyDataSetChanged();
});
//添加
mBtnAdd.setOnClickListener(v->{
String editId=new String(mStuId.getText().toString());
String editName=new String(mMStuName.getText().toString());
String editPhone=new String(mMStuPhone.getText().toString());
Student editStudent=new Student(random[0],editId,editName,editPhone);
mStudentList.add(editStudent);
mStuId.setText("");
mMStuName.setText("");
mMStuPhone.setText("");
mStuAdapter.notifyDataSetChanged();
});可以从列表项拨打对应的电话号码。
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11//方法onBindViewHolder
//拨打电话
holder.mMItemPhone.setOnClickListener(view -> {
String phone=mStudentList.get(position).getPhone();
Intent intent = new Intent();
intent.setAction("android.intent.action.DIAL");
Uri uri = Uri.parse("tel:" + phone);
intent.setData(uri);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
});
实验六
将班级名单以SQLite的方式保存在本地，每个列表项包含：学号和姓名，电话；
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31//activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/fragment_container"
tools:context=".MainActivity">
</androidx.constraintlayout.widget.ConstraintLayout>
//MainActivity
public class MainActivity extends AppCompatActivity {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
String s = getFilesDir() + "/student.db";
SQLiteDatabase database = openOrCreateDatabase(s, MODE_PRIVATE, null);
if (database != null) {
Toast.makeText(this, "数据库创建成功", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(this, "数据库创建失败", Toast.LENGTH_SHORT).show();
}
FragmentManager fm=getSupportFragmentManager();
StuFragment fragment=(StuFragment)fm.findFragmentById(R.id.fragment_container);
if(fragment==null){
fragment=new StuFragment();
fm.beginTransaction().add(R.id.fragment_container,fragment).commit();
}
}
}1
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175//fragment_stu.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/frameLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".StuFragment">
<EditText
android:id="@+id/editName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="72dp"
android:layout_marginTop="60dp"
android:ems="10"
android:inputType="text"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<EditText
android:id="@+id/editPhone"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="72dp"
android:layout_marginTop="128dp"
android:ems="10"
android:inputType="text"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/textView4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="28dp"
android:layout_marginTop="144dp"
android:text="电话"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/textView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="28dp"
android:layout_marginTop="88dp"
android:text="姓名"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="28dp"
android:layout_marginTop="28dp"
android:text="学号"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<EditText
android:id="@+id/editId"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="72dp"
android:layout_marginTop="4dp"
android:ems="10"
android:inputType="text"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="@+id/btnFind"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="292dp"
android:layout_marginTop="40dp"
android:text="查询"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="@+id/btnAdd"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="292dp"
android:layout_marginTop="108dp"
android:text="添加"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recyclerview"
android:layout_width="373dp"
android:layout_height="513dp"
android:layout_marginStart="16dp"
android:layout_marginTop="180dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
//StuFragment
public class StuFragment extends Fragment {
private List<Student> mStudentList=new ArrayList<>();
private TextView mMEditId;
private TextView mMEditName;
private TextView mMMEditPhone;
private Button mBtnAdd;
private Button mMBtnFind;
private RecyclerView mRecyclerView;
private StuAdapter mStuAdapter;
private MyOpenHelper mMyOpenHelper;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view=inflater.inflate(R.layout.fragment_stu, container, false);
mMyOpenHelper = MyOpenHelper.getInstance(getActivity());
mMyOpenHelper.openWriteLink();
mMyOpenHelper.openReadLink();
mMEditId = view.findViewById(R.id.editId);
mMEditName = view.findViewById(R.id.editName);
mMMEditPhone = view.findViewById(R.id.editPhone);
mBtnAdd = view.findViewById(R.id.btnAdd);
mBtnAdd.setOnClickListener(v->{
String id=mMEditId.getText().toString();
String name=mMEditName.getText().toString();
String phone=mMMEditPhone.getText().toString();
mMyOpenHelper.insert(new Student(id,name,phone));
mStudentList=mMyOpenHelper.queryAll();
mStuAdapter.notifyDataSetChanged();
mMEditId.setText("");
mMEditName.setText("");
mMMEditPhone.setText("");
});
mMBtnFind = view.findViewById(R.id.btnFind);
mRecyclerView = view.findViewById(R.id.recyclerview);
mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
mStudentList=mMyOpenHelper.queryAll();
mStuAdapter = new StuAdapter();
mRecyclerView.setAdapter(mStuAdapter);
return view;
}
private class StuAdapter extends RecyclerView.Adapter<StuHolder>{
public StuHolder onCreateViewHolder( ViewGroup parent, int viewType) {
View view=LayoutInflater.from(getActivity()).inflate(R.layout.item,parent,false);
return new StuHolder(view);
}
public void onBindViewHolder( StuHolder holder, int position) {
Student student=mStudentList.get(position);
holder.mItemId.setText(student.getId());
holder.mMItemName.setText(student.getName());
holder.mMItemPhone.setText(student.getPhone());
holder.mMBtnDel.setOnClickListener(v->{
mMyOpenHelper.delete(student.getId());
mStudentList=mMyOpenHelper.queryAll();
mStuAdapter.notifyDataSetChanged();
});
}
public int getItemCount() {
return mStudentList.size();
}
}
public class StuHolder extends RecyclerView.ViewHolder{
private final TextView mItemId;
private final TextView mMItemName;
private final TextView mMItemPhone;
private final Button mMBtnUpdate;
private final Button mMBtnDel;
public StuHolder( View itemView) {
super(itemView);
mItemId = itemView.findViewById(R.id.itemId);
mMItemName = itemView.findViewById(R.id.itemName);
mMItemPhone = itemView.findViewById(R.id.itemPhone);
mMBtnUpdate = itemView.findViewById(R.id.btnUpdate);
mMBtnDel = itemView.findViewById(R.id.btnDel);
}
}
}1
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75//MyOpenHelper
public class MyOpenHelper extends SQLiteOpenHelper {
public static final String DB_NAME = "student.db";
public static final String TABLE_NAME = "stu_info";
public static final int DB_VERSION = 1;
private static MyOpenHelper instance;
private SQLiteDatabase mRDB = null;
private SQLiteDatabase mWDB = null;
public static MyOpenHelper getInstance(Context context) {
if (instance == null) {
instance = new MyOpenHelper(context);
}
return instance;
}
public MyOpenHelper( Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
public MyOpenHelper( Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
super(context, name, factory, version);
}
public SQLiteDatabase openReadLink() {
if (mRDB == null || !mRDB.isOpen()) {
mRDB = instance.getReadableDatabase();
}
return mRDB;
}
public SQLiteDatabase openWriteLink() {
if (mWDB == null || !mWDB.isOpen()) {
mWDB = instance.getWritableDatabase();
}
return mWDB;
}
public void closeLink() {
if (mRDB != null && mRDB.isOpen()) {
mRDB.close();
mRDB = null;
}
if (mWDB != null && mWDB.isOpen()) {
mWDB.close();
mWDB = null;
}
}
public void onCreate(SQLiteDatabase sqLiteDatabase) {
String sql = "create table stu_info(id primary key ,name ,phone )";
sqLiteDatabase.execSQL(sql);
}
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
}
public int insert(Student student){
ContentValues values = new ContentValues();
values.put("id",student.getId());
values.put("name",student.getName());
values.put("phone",student.getPhone());
return (int) mWDB.insert(TABLE_NAME,null,values);
}
public List<Student> queryAll(){
List<Student> studentList=new ArrayList<>();
Cursor cursor = mRDB.query(TABLE_NAME, null, null, null, null, null, null);
while (cursor.moveToNext()){
String id=cursor.getString(0);
String name=cursor.getString(1);
String phone=cursor.getString(2);
Student student=new Student(id,name,phone);
studentList.add(student);
}
cursor.close();
return studentList;
}
public int delete(String id){
return mWDB.delete(TABLE_NAME,"id=?",new String[]{id});
}
}可以删除列表项，添加列表项（数据更新到SQLite数据库）；
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18//添加
mBtnAdd.setOnClickListener(v->{
String id=mMEditId.getText().toString();
String name=mMEditName.getText().toString();
String phone=mMMEditPhone.getText().toString();
mMyOpenHelper.insert(new Student(id,name,phone));
mStudentList=mMyOpenHelper.queryAll();
mStuAdapter.notifyDataSetChanged();
mMEditId.setText("");
mMEditName.setText("");
mMMEditPhone.setText("");
});
//删除
holder.mMBtnDel.setOnClickListener(v->{
mMyOpenHelper.delete(student.getId());
mStudentList=mMyOpenHelper.queryAll();
mStuAdapter.notifyDataSetChanged();
});可以读取联系人(使用内容提供者)，将联系人的名字和电话号码读入到名单列表并插入数据库；
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23//StuFragment
//检查获取通讯录权限
private void checkPermission() {
//判断是否有权限
if (ContextCompat.checkSelfPermission(getContext(), android.Manifest.permission.READ_CONTACTS)
!= PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(getActivity(), new String[]{Manifest.permission.READ_CONTACTS}, 201);
}
}
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
checkPermission();
}
mMBtnFind.setOnClickListener(v -> {
List<Student> contacts = ContactUtils.getContacts(getActivity());
for (int i = 0; i < contacts.size(); i++) {
Student student = contacts.get(i);
mMyOpenHelper.insert(student);
}
mStudentList = mMyOpenHelper.queryAll();
mStuAdapter.notifyDataSetChanged();
});1
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22public class ContactUtils {
public static final String ID = ContactsContract.CommonDataKinds.Phone.CONTACT_ID;//联系人ID
public static final String NUM = ContactsContract.CommonDataKinds.Phone.NUMBER;//电话号码
public static final String NAME = ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME;//姓名
public static final Uri phoneUri = ContactsContract.CommonDataKinds.Phone.CONTENT_URI;
public static List<Student> getContacts(Context context) {
List<Student> students = new ArrayList<>();
ContentResolver cr = context.getContentResolver();
Cursor cursor = cr.query(phoneUri, new String[]{ID, NUM, NAME}, null, null, null);
while (cursor.moveToNext()) {
//随机生成id
String id = String.valueOf((int) (Math.random() * 100000));
String name = cursor.getString(cursor.getColumnIndex(NAME));
String num = cursor.getString(cursor.getColumnIndex(NUM));
Student student = new Student(id, name, num);
students.add(student);
}
cursor.close();
return students;
}
}支持在新的页面中学号和姓名，电话。
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7holder.mMBtnUpdate.setOnClickListener(v->{
Intent intent=new Intent(getActivity(),NewActivity.class);
intent.putExtra("id",student.getId());
intent.putExtra("name",student.getName());
intent.putExtra("phone",student.getPhone());
startActivity(intent);
});1
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69//activity_new.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".NewActivity">
<TextView
android:id="@+id/newName"
android:layout_width="74dp"
android:layout_height="40dp"
android:layout_marginStart="60dp"
android:layout_marginTop="144dp"
android:text="TextView"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/newId"
android:layout_width="74dp"
android:layout_height="40dp"
android:layout_marginStart="60dp"
android:layout_marginTop="72dp"
android:text="TextView"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/newPhone"
android:layout_width="74dp"
android:layout_height="40dp"
android:layout_marginStart="64dp"
android:layout_marginTop="220dp"
android:text="TextView"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="@+id/btnBack"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="返回"
tools:layout_editor_absoluteX="204dp"
tools:layout_editor_absoluteY="132dp" />
</androidx.constraintlayout.widget.ConstraintLayout>
//NewActivity
public class NewActivity extends AppCompatActivity {
private TextView mNewId;
private TextView mNewName;
private TextView mNewPhone;
private Button mBtnBack;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_new);
mNewId = findViewById(R.id.newId);
mNewName = findViewById(R.id.newName);
mNewPhone = findViewById(R.id.newPhone);
mBtnBack = findViewById(R.id.btnBack);
Intent intent = getIntent();
String id=intent.getStringExtra("id");
String name=intent.getStringExtra("name");
String phone=intent.getStringExtra("phone");
mNewId.setText(id);
mNewName.setText(name);
mNewPhone.setText(phone);
mBtnBack.setOnClickListener(v-> {
finish();
});
}
}
实验七
在SQLite版本的班级名单基础上实现以下功能，设计修改列表项的Fragment页面，支持调用相机和读取图库中照片；
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20//AndroidManifest.xml
<uses-permission android:name="android.permission.WRITE_CONTACTS" />
<uses-permission android:name="android.permission.READ_CONTACTS" />
<uses-permission android:name="android.permission.GET_ACCOUNTS" />
<uses-permission android:name="android.permission.CALL_PHONE" />
<provider
android:name="androidx.core.content.FileProvider"
android:authorities="@string/file_provider"
android:grantUriPermissions="true"
android:exported="false">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="@xml/file_paths"/>
</provider>
//xml文件夹下file_paths.xml
<paths>
<external-path
name="external_files"
path="." />
</paths>1
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34//StuFragment
//为头像设置点击事件，选择头像是从拍照中获取还是从相册中获取
mImageView.setOnClickListener(v -> {
final String[] items=new String[]{"拍照","相册"};
AlertDialog.Builder builder=new AlertDialog.Builder(getContext());
builder.setTitle("请选择头像获取方式");
builder.setItems(items,new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
switch (which) {
case 0:
takePhoto();
break;
case 1:
choosePhoto();
break;
}
}
private void choosePhoto() {
Intent intent = new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
register.launch(intent);
}
private void takePhoto() {
File outputImage = new File(getContext().getExternalCacheDir(), "output_image.jpg");
if (outputImage.exists()) outputImage.delete();
String string = getString(R.string.file_provider);
imageUri = FileProvider.getUriForFile(getContext(), string, outputImage);
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
register.launch(intent);
}
});
builder.create().show();
});将拍摄的或选中的照片设置为该名单对应的头像，并在列表中更新显示；
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58//StuFragment
//获取回传的图片设置成头像
register = registerForActivityResult(new ActivityResultContracts.StartActivityForResult(), result -> {
if (result.getResultCode() == RESULT_OK) {
Intent intent = result.getData();
//判断是拍照还是选择照片
try {
if (intent != null && intent.getData() != null) { //选择照片
Uri uri = intent.getData();
Bitmap bitmap = BitmapFactory.decodeStream(getContext().getContentResolver()
.openInputStream(uri));
mImageView.setImageBitmap(bitmap);
image = bitmap2Bytes(bitmap);
} else {//选择拍照
Bitmap bitmap = BitmapFactory.decodeStream(
getContext().getContentResolver().openInputStream(imageUri));
mImageView.setImageBitmap(bitmap);
image = bitmap2Bytes(bitmap);
}
} catch (FileNotFoundException e) {
throw new RuntimeException(e);
}
}
});
//为添加按钮设置点击事件，将输入的学生信息保存到数据库后展示到列表中
mBtnAdd.setOnClickListener(v -> {
String id = mEditId.getText().toString();
String name = mEditName.getText().toString();
String phone = mEditPhone.getText().toString();
Student student1 = new Student(id, name, phone,image);
mMyOpenHelper.insert(student1);
mStudentList = mMyOpenHelper.queryAll();
mStuAdapter.notifyDataSetChanged();
mEditId.setText("");
mEditName.setText("");
mEditPhone.setText("");
});
//StuAdapter
//将bytes转换为Bitmap,将数组中的图片二进制转换成图片
private Bitmap bytes2Bitmap(byte[] bytes) {
return BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
}
public void onBindViewHolder( StuHolder holder, int position) {
Student student = mStudentList.get(position);
holder.mItemId.setText(student.getId());
holder.mItemName.setText(student.getName());
holder.mItemPhone.setText(student.getPhone());
byte[] byteImage = student.getImage();
Bitmap bitmap = bytes2Bitmap(byteImage);
holder.mImageView.setImageBitmap(bitmap);
holder.mBtnDel.setOnClickListener(v -> {
mMyOpenHelper.delete(student.getId());
mStudentList = mMyOpenHelper.queryAll();
mStuAdapter.notifyDataSetChanged();
});将名单和图片文件的对应关系保存在SQLite数据库中，下次重启应用的时候可以看到名单的头像；
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32public long insert(Student student) {
ContentValues values = new ContentValues();
values.put("id", student.getId());
values.put("name", student.getName());
values.put("phone", student.getPhone());
values.put("image", student.getImage());
return mWDB.insert(TABLE_NAME, null, values);
}
public int delete(String id) {
return mWDB.delete(TABLE_NAME, "id=?", new String[]{id});
}
public int update(Student student) {
ContentValues values = new ContentValues();
values.put("name", student.getName());
values.put("phone", student.getPhone());
return mWDB.update(TABLE_NAME, values, "id=?", new String[]{student.getId()});
}
public List<Student> queryAll() {
List<Student> list = new ArrayList<>();
Cursor cursor = mRDB.query(TABLE_NAME, null, null, null, null, null, null);
while (cursor.moveToNext()) {
String id = cursor.getString(0);
String name = cursor.getString(1);
String phone = cursor.getString(2);
byte[] image = cursor.getBlob(3);
Student student = new Student(id, name, phone,image);
list.add(student);
}
cursor.close();
return list;
}
###实验八