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

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class FirstActivity extends Activity {
    private Button firstButton;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_first);
        
        firstButton = (Button)findViewById(R.id.firstButton);
        firstButton.setText(R.string.firstButton);
        firstButton.setOnClickListener(new ButtonListener());
    }
    
    class ButtonListener implements OnClickListener{

        @Override
        public void onClick(View v) {
            Intent intent = new Intent();
            /*setClass方法：
                    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
                    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
            */
            intent.setClass(FirstActivity.this, SecondActivity.class);
            FirstActivity.this.startActivity(intent);
        }
        
    }

}

 FirstActivity.xml

<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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".FirstActivity" 
    android:orientation="vertical">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/first" />
    
    <Button
        android:id="@+id/firstButton"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>
</LinearLayout>

SecondActivity.java

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class SecondActivity extends Activity{
    private Button SecondtButton;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        SecondtButton = (Button)findViewById(R.id.SecondtButton);
        SecondtButton.setText(R.string.secondtButton);
        SecondtButton.setOnClickListener(new ButtonListener());
        
    }
    class ButtonListener implements OnClickListener{

        @Override
        public void onClick(View v) {
            Intent intent = new Intent();
            intent.setClass(SecondActivity.this, ThirdActivity.class);
            SecondActivity.this.startActivity(intent);
            finish();//该方法使Activity跳转到下一个Activity时关掉这个Activity
        }
        
    }
}

 SecondActivity.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    
    
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/second"
        ></TextView>
    
    
    <Button
        android:id="@+id/SecondtButton"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        ></Button>
</LinearLayout>

ThirdActivity.java

import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class ThirdActivity extends Activity{
    private Button ThirdButton;
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_third);
        
        ThirdButton = (Button)findViewById(R.id.ThirdActivity);
        ThirdButton.setText(R.string.thirdtButton);
        ThirdButton.setOnClickListener(new ButtonListener());
    }
    class ButtonListener implements OnClickListener{
        public void onClick(View v) {
            
             Uri uri = Uri.parse("smsto://0800000123");    
             Intent it = new Intent(Intent.ACTION_SENDTO, uri);    
             it.putExtra("sms_body", "The SMS text");    
             ThirdActivity.this.startActivity(it);   
        }
    }
}

 ThirdActivity.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/third"
    />
    
    <Button
        android:id="@+id/ThirdActivity"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        />

</LinearLayout>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.mars.activity06"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="4"
        android:targetSdkVersion="18" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.mars.activity06.FirstActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <!--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-->
        <activity android:name="com.mars.activity06.SecondActivity" android:label="@string/second"/>
        <activity android:name="com.mars.activity06.ThirdActivity" android:label="@string/third"/>"
    </application>

</manifest>

 string.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <string name="app_name">Activity06</string>
    <string name="action_settings">Settings</string>
    <string name="first">FirstActivity</string>
    <string name="firstButton">FirstButton</string>
    <string name="second">SecondActivity</string>
    <string name="secondtButton">SecondButton</string>
    <string name="third">ThirdActivity</string>
    <string name="thirdtButton">ThirdButton</string>

</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

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity {
    //代表按钮对象的引用
    private Button myButton;
    @Override
    //复写父类当中的onCreate方法，Activity第一次运行时会调用这个方法
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        myButton = (Button) findViewById(R.id.myButton);
        myButton.setOnClickListener(new myButtonListener());
        
    }
    //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）
    class myButtonListener implements OnClickListener{

        //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 
        public void onClick(View v) {
            
            Intent intent = new Intent();//生成一个Intent对象
            
            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
            
            //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
            /*
             * setClass函数的第一个参数是一个Context对象
             * 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
             * */
            intent.setClass(MainActivity.this, OtherActivity.class);
            //通过Intent对象启动另外一个Activity
            MainActivity.this.startActivity(intent);
            
            
            
            /*
            //以下的4行代码将启动发送短信的Activity，
            Uri uri = Uri.parse("smsto://0800000123");    
            Intent intent = new Intent(Intent.ACTION_SENDTO, uri);    
            intent.putExtra("sms_body", "The SMS text");    
            startActivity(intent);
         */
        }
    }
}

 main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <!-- 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 -->
    <Button
        android:id="@+id/myButton"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/Button"
        />

</LinearLayout>

 OtherActivity.java

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;

public class OtherActivity extends Activity{
    private TextView myTextView;
    protected void onCreate(Bundle savedInstanceState) {
        
        super.onCreate(savedInstanceState);
        setContentView(R.layout.other);
        //取得从上一个Activity当中传递过来的Intent对象
        Intent intent = getIntent();
        //从Intent当中根据key取得value
        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
        
        myTextView = (TextView) findViewById(R.id.myTextView);
        myTextView.setText(number);
        
    }
    
}

 other.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    
    
    <TextView
        android:id="@+id/myTextView"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/TextView"
        />"

</LinearLayout>

 AndriodManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.mars.conver_activity"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="18" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.mars.conver_activity.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name="com.mars.conver_activity.OtherActivity" android:label="@string/OtherActivity"/>"
    </application>

</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

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity {
    private Button button;
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        button = (Button) findViewById(R.id.button);
        button.setOnClickListener(new ButtonListener());
    }
    class ButtonListener implements OnClickListener{
        public void onClick(View v) {
            Intent intent = new Intent();
            intent.putExtra("com.mars.second_intent.Age", 20);
            intent.putExtra("com.mars.second_intent.Number", "13112266075");
            intent.setClass(MainActivity.this, OtherActivity.class);
            MainActivity.this.startActivity(intent);
        }
    } 
}

activity_main.xml

<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:id="@+id/textview1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />
    
    <Button 
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/textview1"
        android:text="启动第二个Activity"
        />

</RelativeLayout>

OtherActivity.java

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;

public class OtherActivity extends Activity{
    private TextView textview;
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.other);
        Intent intent = getIntent();
        String str = intent.getStringExtra("com.mars.second_intent.Number");
        int age = intent.getIntExtra("com.mars.second_intent.Age", 10);
        
        textview = (TextView) findViewById(R.id.textview);
        textview.setText("Number="+str+"age="+age);
    }
}

other.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    
    
    <TextView 
        android:id="@+id/textview"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="zhognguo"
        />

</LinearLayout>

 AndriodManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.mars.second_intent"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="17"
        android:targetSdkVersion="18" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.mars.second_intent.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        
        <activity 
            android:name="com.mars.second_intent.OtherActivity"
            android:label="第二个Activity"
            ></activity>
    </application>

</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>