多个Activity和Intent
Intent是Android应用程序组件之一，在Android系统当中表示一种意图，Intent中包含了一组信息：
最重要的内容是action（动作）和data（数据）
Component name 表示要启动哪个Activity
FirstActivity.java
1 import android.os.Bundle; 2 import android.app.Activity; 3 import android.content.Intent; 4 import android.view.View; 5 import android.view.View.OnClickListener; 6 import android.widget.Button; 7 8 public class FirstActivity extends Activity { 9 private Button firstButton; 10 @Override 11 protected void onCreate(Bundle savedInstanceState) { 12 super.onCreate(savedInstanceState); 13 setContentView(R.layout.activity_first); 14 15 firstButton = (Button)findViewById(R.id.firstButton); 16 firstButton.setText(R.string.firstButton); 17 firstButton.setOnClickListener(new ButtonListener()); 18 } 19 20 class ButtonListener implements OnClickListener{ 21 22 @Override 23 public void onClick(View v) { 24 Intent intent = new Intent(); 25 /*setClass方法： 26 第一个参数是一个Context对像，Context是一个类，Activity是Context类的子类，也就是说，所有的Activity对象都可以向上转型为Context对象 27 第二个参数是一个Class对象,在当前场景下，传入需要启动的Activity类的Class对象 28 */ 29 intent.setClass(FirstActivity.this, SecondActivity.class); 30 FirstActivity.this.startActivity(intent); 31 } 32 33 } 34 35 }
FirstActivity.xml
1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 2 xmlns:tools="http://schemas.android.com/tools" 3 android:layout_width="match_parent" 4 android:layout_height="match_parent" 5 android:paddingBottom="@dimen/activity_vertical_margin" 6 android:paddingLeft="@dimen/activity_horizontal_margin" 7 android:paddingRight="@dimen/activity_horizontal_margin" 8 android:paddingTop="@dimen/activity_vertical_margin" 9 tools:context=".FirstActivity" 10 android:orientation="vertical"> 11 12 <TextView 13 android:layout_width="wrap_content" 14 android:layout_height="wrap_content" 15 android:text="@string/first" /> 16 17 <Button 18 android:id="@+id/firstButton" 19 android:layout_width="fill_parent" 20 android:layout_height="wrap_content"/> 21 </LinearLayout>
SecondActivity.java
1 import android.app.Activity; 2 import android.content.Intent; 3 import android.os.Bundle; 4 import android.view.View; 5 import android.view.View.OnClickListener; 6 import android.widget.Button; 7 8 public class SecondActivity extends Activity{ 9 private Button SecondtButton; 10 @Override 11 protected void onCreate(Bundle savedInstanceState) { 12 super.onCreate(savedInstanceState); 13 setContentView(R.layout.activity_second); 14 SecondtButton = (Button)findViewById(R.id.SecondtButton); 15 SecondtButton.setText(R.string.secondtButton); 16 SecondtButton.setOnClickListener(new ButtonListener()); 17 18 } 19 class ButtonListener implements OnClickListener{ 20 21 @Override 22 public void onClick(View v) { 23 Intent intent = new Intent(); 24 intent.setClass(SecondActivity.this, ThirdActivity.class); 25 SecondActivity.this.startActivity(intent); 26 finish();//该方法使Activity跳转到下一个Activity时关掉这个Activity 27 } 28 29 } 30 }
SecondActivity.xml
1 <?xml version="1.0" encoding="utf-8"?> 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 3 android:layout_width="match_parent" 4 android:layout_height="match_parent" 5 android:orientation="vertical" > 6 7 8 <TextView 9 android:layout_width="fill_parent" 10 android:layout_height="wrap_content" 11 android:text="@string/second" 12 ></TextView> 13 14 15 <Button 16 android:id="@+id/SecondtButton" 17 android:layout_width="fill_parent" 18 android:layout_height="wrap_content" 19 ></Button> 20 </LinearLayout>
ThirdActivity.java
1 import android.app.Activity; 2 import android.content.Intent; 3 import android.net.Uri; 4 import android.os.Bundle; 5 import android.view.View; 6 import android.view.View.OnClickListener; 7 import android.widget.Button; 8 9 public class ThirdActivity extends Activity{ 10 private Button ThirdButton; 11 protected void onCreate(Bundle savedInstanceState) { 12 super.onCreate(savedInstanceState); 13 setContentView(R.layout.activity_third); 14 15 ThirdButton = (Button)findViewById(R.id.ThirdActivity); 16 ThirdButton.setText(R.string.thirdtButton); 17 ThirdButton.setOnClickListener(new ButtonListener()); 18 } 19 class ButtonListener implements OnClickListener{ 20 public void onClick(View v) { 21 22 Uri uri = Uri.parse("smsto://0800000123"); 23 Intent it = new Intent(Intent.ACTION_SENDTO, uri); 24 it.putExtra("sms_body", "The SMS text"); 25 ThirdActivity.this.startActivity(it); 26 } 27 } 28 }
ThirdActivity.xml
1 <?xml version="1.0" encoding="utf-8"?> 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 3 android:layout_width="match_parent" 4 android:layout_height="match_parent" 5 android:orientation="vertical" > 6 <TextView 7 android:layout_width="fill_parent" 8 android:layout_height="wrap_content" 9 android:text="@string/third" 10 /> 11 12 <Button 13 android:id="@+id/ThirdActivity" 14 android:layout_width="fill_parent" 15 android:layout_height="wrap_content" 16 /> 17 18 </LinearLayout>
AndroidManifest.xml
1 <?xml version="1.0" encoding="utf-8"?> 2 <manifest xmlns:android="http://schemas.android.com/apk/res/android" 3 package="com.mars.activity06" 4 android:versionCode="1" 5 android:versionName="1.0" > 6 7 <uses-sdk 8 android:minSdkVersion="4" 9 android:targetSdkVersion="18" /> 10 11 <application 12 android:allowBackup="true" 13 android:icon="@drawable/ic_launcher" 14 android:label="@string/app_name" 15 android:theme="@style/AppTheme" > 16 <activity 17 android:name="com.mars.activity06.FirstActivity" 18 android:label="@string/app_name" > 19 <intent-filter> 20 <action android:name="android.intent.action.MAIN" /> 21 22 <category android:name="android.intent.category.LAUNCHER" /> 23 </intent-filter> 24 </activity> 25 <!--每当程序当中有个Activity的时候就需要使用<activity/>标签对该Activity进行注册 有两个属性name和lable name的值是这个Activity的包名和类名 lable可以自定义--> 26 <activity android:name="com.mars.activity06.SecondActivity" android:label="@string/second"/> 27 <activity android:name="com.mars.activity06.ThirdActivity" android:label="@string/third"/>" 28 </application> 29 30 </manifest>
string.xml
1 <?xml version="1.0" encoding="utf-8"?> 2 <resources> 3 4 <string name="app_name">Activity06</string> 5 <string name="action_settings">Settings</string> 6 <string name="first">FirstActivity</string> 7 <string name="firstButton">FirstButton</string> 8 <string name="second">SecondActivity</string> 9 <string name="secondtButton">SecondButton</string> 10 <string name="third">ThirdActivity</string> 11 <string name="thirdtButton">ThirdButton</string> 12 13 </resources>
在Activity之间可以通过Intent对象传递数据
使用putExtra()系列方法向Intent对象当中存储数据
使用getXXXExtra()系列方法从Intent对象当中取出数据
MainActivity.java
1 import android.app.Activity; 2 import android.content.Intent; 3 import android.os.Bundle; 4 import android.view.View; 5 import android.view.View.OnClickListener; 6 import android.widget.Button; 7 8 public class MainActivity extends Activity { 9 //代表按钮对象的引用 10 private Button myButton; 11 @Override 12 //复写父类当中的onCreate方法，Activity第一次运行时会调用这个方法 13 protected void onCreate(Bundle savedInstanceState) { 14 super.onCreate(savedInstanceState); 15 setContentView(R.layout.main); 16 17 myButton = (Button) findViewById(R.id.myButton); 18 myButton.setOnClickListener(new myButtonListener()); 19 20 } 21 //以下是一个内部类，这个内部类的对象是一个监听器（如果对监听器不是很熟悉，可以参考设计模式当中的观察者模式） 22 class myButtonListener implements OnClickListener{ 23 24 //生成该类的对象，并将其注册到控件上。如果该控件被用户按下，就会执行onClick方法 25 public void onClick(View v) { 26 27 Intent intent = new Intent();//生成一个Intent对象 28 29 intent.putExtra("number", "13112266075");//在Intent对象当中添加一个键值对,键的取名应该加上这个Activity的包名代表着那个包下的数据,格式包名.键的名字，如果不需要传递数据，这步可以不要 30 31 //设置Intent对象要启动的Activity,不能直接写this，因为直接写this代表的是本类的对象，也就是myButtonListener这个对象 32 /* 33 * setClass函数的第一个参数是一个Context对象 34 * Context是一个类，Activity是Context类的子类，也就是说，所有的Activity对象，都可以向上转型为Context对象 35 * */ 36 intent.setClass(MainActivity.this, OtherActivity.class); 37 //通过Intent对象启动另外一个Activity 38 MainActivity.this.startActivity(intent); 39 40 41 42 /* 43 //以下的4行代码将启动发送短信的Activity， 44 Uri uri = Uri.parse("smsto://0800000123"); 45 Intent intent = new Intent(Intent.ACTION_SENDTO, uri); 46 intent.putExtra("sms_body", "The SMS text"); 47 startActivity(intent); 48 */ 49 } 50 } 51 }
main.xml
1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 2 xmlns:tools="http://schemas.android.com/tools" 3 android:orientation="vertical" 4 android:layout_width="match_parent" 5 android:layout_height="match_parent" 6 android:paddingBottom="@dimen/activity_vertical_margin" 7 android:paddingLeft="@dimen/activity_horizontal_margin" 8 android:paddingRight="@dimen/activity_horizontal_margin" 9 android:paddingTop="@dimen/activity_vertical_margin" 10 tools:context=".MainActivity" > 11 12 <!-- 下面的标签声明了一个Buttin(按钮)控件，并为这个控件设置了ID，这个ID会被注册到R.java文件当中 --> 13 <Button 14 android:id="@+id/myButton" 15 android:layout_width="fill_parent" 16 android:layout_height="wrap_content" 17 android:text="@string/Button" 18 /> 19 20 </LinearLayout>
OtherActivity.java
1 import android.app.Activity; 2 import android.content.Intent; 3 import android.os.Bundle; 4 import android.widget.TextView; 5 6 public class OtherActivity extends Activity{ 7 private TextView myTextView; 8 protected void onCreate(Bundle savedInstanceState) { 9 10 super.onCreate(savedInstanceState); 11 setContentView(R.layout.other); 12 //取得从上一个Activity当中传递过来的Intent对象 13 Intent intent = getIntent(); 14 //从Intent当中根据key取得value 15 String number = intent.getStringExtra("number");//该方法还有第二个参数，是一个值,表示如果上一个Activity中的键没有值，就将这个方法中的第二个参数赋值number这个变量 16 17 myTextView = (TextView) findViewById(R.id.myTextView); 18 myTextView.setText(number); 19 20 } 21 22 }
other.xml
1 <?xml version="1.0" encoding="utf-8"?> 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 3 android:layout_width="match_parent" 4 android:layout_height="match_parent" 5 android:orientation="vertical" > 6 7 8 <TextView 9 android:id="@+id/myTextView" 10 android:layout_width="fill_parent" 11 android:layout_height="wrap_content" 12 android:text="@string/TextView" 13 />" 14 15 </LinearLayout>
AndriodManifest.xml
1 <?xml version="1.0" encoding="utf-8"?> 2 <manifest xmlns:android="http://schemas.android.com/apk/res/android" 3 package="com.mars.conver_activity" 4 android:versionCode="1" 5 android:versionName="1.0" > 6 7 <uses-sdk 8 android:minSdkVersion="8" 9 android:targetSdkVersion="18" /> 10 11 <application 12 android:allowBackup="true" 13 android:icon="@drawable/ic_launcher" 14 android:label="@string/app_name" 15 android:theme="@style/AppTheme" > 16 <activity 17 android:name="com.mars.conver_activity.MainActivity" 18 android:label="@string/app_name" > 19 <intent-filter> 20 <action android:name="android.intent.action.MAIN" /> 21 22 <category android:name="android.intent.category.LAUNCHER" /> 23 </intent-filter> 24 </activity> 25 <activity android:name="com.mars.conver_activity.OtherActivity" android:label="@string/OtherActivity"/>" 26 </application> 27 28 </manifest>
string.xml
<?xml version="1.0" encoding="utf-8"?> <resources> <string name="app_name">Activity转换</string> <string name="action_settings">Settings</string> <string name="Button">start next Button</string> <string name="TextView">I am coming</string> <string name="OtherActivity">OtherActivity</string> </resources>
MainActivity.java
1 import android.app.Activity; 2 import android.content.Intent; 3 import android.os.Bundle; 4 import android.view.View; 5 import android.view.View.OnClickListener; 6 import android.widget.Button; 7 8 public class MainActivity extends Activity { 9 private Button button; 10 protected void onCreate(Bundle savedInstanceState) { 11 super.onCreate(savedInstanceState); 12 setContentView(R.layout.activity_main); 13 14 button = (Button) findViewById(R.id.button); 15 button.setOnClickListener(new ButtonListener()); 16 } 17 class ButtonListener implements OnClickListener{ 18 public void onClick(View v) { 19 Intent intent = new Intent(); 20 intent.putExtra("com.mars.second_intent.Age", 20); 21 intent.putExtra("com.mars.second_intent.Number", "13112266075"); 22 intent.setClass(MainActivity.this, OtherActivity.class); 23 MainActivity.this.startActivity(intent); 24 } 25 } 26 }
activity_main.xml
1 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 2 xmlns:tools="http://schemas.android.com/tools" 3 android:layout_width="match_parent" 4 android:layout_height="match_parent" 5 android:paddingBottom="@dimen/activity_vertical_margin" 6 android:paddingLeft="@dimen/activity_horizontal_margin" 7 android:paddingRight="@dimen/activity_horizontal_margin" 8 android:paddingTop="@dimen/activity_vertical_margin" 9 tools:context=".MainActivity" > 10 11 <TextView 12 android:id="@+id/textview1" 13 android:layout_width="wrap_content" 14 android:layout_height="wrap_content" 15 android:text="@string/hello_world" /> 16 17 <Button 18 android:id="@+id/button" 19 android:layout_width="wrap_content" 20 android:layout_height="wrap_content" 21 android:layout_below="@id/textview1" 22 android:text="启动第二个Activity" 23 /> 24 25 </RelativeLayout>
OtherActivity.java
1 import android.app.Activity; 2 import android.content.Intent; 3 import android.os.Bundle; 4 import android.widget.TextView; 5 6 public class OtherActivity extends Activity{ 7 private TextView textview; 8 protected void onCreate(Bundle savedInstanceState) { 9 super.onCreate(savedInstanceState); 10 setContentView(R.layout.other); 11 Intent intent = getIntent(); 12 String str = intent.getStringExtra("com.mars.second_intent.Number"); 13 int age = intent.getIntExtra("com.mars.second_intent.Age", 10); 14 15 textview = (TextView) findViewById(R.id.textview); 16 textview.setText("Number="+str+"age="+age); 17 } 18 }
other.xml
1 <?xml version="1.0" encoding="utf-8"?> 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 3 android:layout_width="match_parent" 4 android:layout_height="match_parent" 5 android:orientation="vertical" > 6 7 8 <TextView 9 android:id="@+id/textview" 10 android:layout_width="wrap_content" 11 android:layout_height="wrap_content" 12 android:text="zhognguo" 13 /> 14 15 </LinearLayout>
AndriodManifest.xml
1 <?xml version="1.0" encoding="utf-8"?> 2 <manifest xmlns:android="http://schemas.android.com/apk/res/android" 3 package="com.mars.second_intent" 4 android:versionCode="1" 5 android:versionName="1.0" > 6 7 <uses-sdk 8 android:minSdkVersion="17" 9 android:targetSdkVersion="18" /> 10 11 <application 12 android:allowBackup="true" 13 android:icon="@drawable/ic_launcher" 14 android:label="@string/app_name" 15 android:theme="@style/AppTheme" > 16 <activity 17 android:name="com.mars.second_intent.MainActivity" 18 android:label="@string/app_name" > 19 <intent-filter> 20 <action android:name="android.intent.action.MAIN" /> 21 22 <category android:name="android.intent.category.LAUNCHER" /> 23 </intent-filter> 24 </activity> 25 26 <activity 27 android:name="com.mars.second_intent.OtherActivity" 28 android:label="第二个Activity" 29 ></activity> 30 </application> 31 32 </manifest>
string.xml
<?xml version="1.0" encoding="utf-8"?> <resources> <string name="app_name">Second_Intent</string> <string name="action_settings">Settings</string> <string name="hello_world">Hello world!</string> </resources>