Android 广播(Broadcast)简单的学习

广播事件的流程
①注册广播事件：注册方式有两种，一种是静态注册，就是在AndroidManifest.xml文件中定义，注册的广播接收器必须要继承BroadcastReceiver；另一种是动态注册，是在程序中使用Context.registerReceiver注册，注册的广播接收器相当于一个匿名类。两种方式都需要IntentFIlter。
②发送广播事件：通过Context.sendBroadcast来发送，由Intent来传递注册时用到的Action。
③接收广播事件：当发送的广播被接收器监听到后，会调用它的onReceive()方法，并将包含消息的Intent对象传给它。onReceive中代码的执行时间不要超过5s，否则Android会弹出超时dialog。

静态注册广播Demo：

manifest

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

    <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.rainwii.client.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>
        <receiver 
            android:name="com.rainwii.client.MyBroadcastReceive"
            >
            <intent-filter>
                <action android:name="ccc"></action>
             </intent-filter>
        </receiver>
    </application>

</manifest>

MainActivity

package com.rainwii.client;

import com.rainwii.main.R;

import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager.NameNotFoundException;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity {
Button startappbutton;
String str;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        startappbutton= (Button) findViewById(R.id.button1);
        startappbutton.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                Intent intent = new Intent();
                intent.putExtra("msg", "你好，我是一个广播");
                intent.setAction("ccc");
                intent.setClass(MainActivity.this, MyBroadcastReceive.class);
                MainActivity.this.sendBroadcast(intent);
            }
        });
              
      
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
    
}

MyBroadcastReceive

package com.rainwii.client;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;

public class MyBroadcastReceive extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
    
        String string=intent.getStringExtra("msg");
        Toast.makeText(context, "广播被收到了！
"+string, Toast.LENGTH_SHORT).show();
    }
}

动态注册广播Demo：

        // 注册自定义动态广播消息  
        IntentFilter filter_dynamic = new IntentFilter();  
        filter_dynamic.addAction(DYNAMICACTION);  
        registerReceiver(dynamicReceiver, filter_dynamic);  
        // 注册系统动态广播消息  
        IntentFilter filter_system = new IntentFilter();  
        filter_system.addAction(SYSTEMACTION);  
        registerReceiver(systemReceiver, filter_system);         

MainActivity

package com.rainwii.client;


import android.os.Bundle;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;

import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity {
Button staticbutton,dynamicbutton;
String str;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
//        staticbutton= (Button) findViewById(R.id.button1);
        dynamicbutton= (Button) findViewById(R.id.button2);
//        staticbutton.setOnClickListener(new OnClickListener() {
//            
//            @Override
//            public void onClick(View v) {
//                // TODO Auto-generated method stub
//                Intent intent = new Intent();
//                intent.putExtra("msg", "你好，我是一个静态广播");
//                intent.setAction("ccc");
//                //intent.setClass(MainActivity.this, MyBroadcastReceive.class);
//                MainActivity.this.sendBroadcast(intent);
//                
//            }
//        });
        dynamicbutton.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                Log.e("MainActivity", "发送自定义动态注册广播消息");  
                Intent intent = new Intent();  
                intent.setAction("aaa");  
                intent.putExtra("msg", "接收动态注册广播成功！");  
                sendBroadcast(intent);  
            }
        });
              
      
    }

    @Override
    protected void onStart() {
        // TODO Auto-generated method stub
        super.onStart();
        // 注册自定义动态广播消息  
        IntentFilter filter_dynamic = new IntentFilter();  
        filter_dynamic.addAction("aaa");  
        registerReceiver(dynamicReceiver, filter_dynamic);  
       
    }

    private BroadcastReceiver dynamicReceiver = new BroadcastReceiver() {  
        
        @Override  
        public void onReceive(Context context, Intent intent) {  
            Log.e("MainActivity", "接收自定义动态注册广播消息");  
            if(intent.getAction().equals("aaa")){  
                String msg = intent.getStringExtra("msg");  
                Toast.makeText(context, msg, Toast.LENGTH_LONG).show();  
            }  
        }  
    };  
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
    
}

===============================================================

需求：如果c应用想通过广播启动d应用的Activity或者服务。

方法：可以在c应用中启动广播，d应用接收到广播使用startactivity启动页面。