Android广播机制基础

一、广播做什么

广播用于进行系统级别的消息通知。

二、接受广播

动态注册监听（两个变量）:1.IntentFilter2.自定义的Recevier的子类3.注册receiver，注销receiver例如：动态监听网络变化：

public class MainActivity extends Activity {private IntentFilter intentFilter;private NetworkChangeReceiver networkChangeReceiver;@Overrideprotected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    intentFilter = new IntentFilter();    //为intentFilter添加Action（该Action监听网络变化）    intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");    networkChangeReceiver = new NetworkChangeReceiver();    registerReceiver(networkChangeReceiver, intentFilter);}@Overrideprotected void onDestroy() {    super.onDestroy();    unregisterReceiver(networkChangeReceiver);}class NetworkChangeReceiver extends BroadcastReceiver {@Overridepublic void onReceive(Context context, Intent intent) {    Toast.makeText(context, "network changes",    Toast.LENGTH_SHORT).show();}}}

静态注册监听（APP启动时，就进行监听了）：1.在AndroidManifest.xml中进行注册receiver例如监听开机启动事件：

//Receiver类，当监听到开机事件时，出发onReceive方法public class BootCompleteReceiver extends BroadcastReceiver {@Overridepublic void onReceive(Context context, Intent intent) {Toast.makeText(context, "Boot Complete", Toast.LENGTH_LONG).show();}}注册：<receiver android:name=".BootCompleteReceiver">            <intent-filter>                <action android:name="android.intent.action.BOOT_COMPLETED"></action>            </intent-filter>        </receiver>

由于监听开机启动事件，所以app要获得开机自启权限：

<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />

三、发送广播（接受者都采用静态注册）

1.发送标准广播：

//定义Intent，并设置actionIntent intent = new Intent("com.example.broadcasttest.MY_BROADCAST");//发送广播sendBroadcast(intent);

2.有序广播：

Intent intent = new Intent("com.example.broadcasttest.MY_BROADCAST");//有序广播和标准广播的代码区别sendOrderedBroadcast(intent, null);}

三、本地广播（动态监听）
只有本进程才能接受，其他广播可以进行跨进程接受。

1.三个变量：    IntenFilter，LocalBroadcastManager,自定义的Receiver子类。使用方法：

 intentFilter = new IntentFilter();        intentFilter.addAction("com.fzd.LocalReceive");        localBroadcastManager = LocalBroadcastManager.getInstance(this);        button.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                Intent intent = new Intent("com.fzd.LocalReceive");                localBroadcastManager.sendBroadcast(intent);            }        });        localReceiver = new LocalReceiver();        localBroadcastManager.registerReceiver(localReceiver, intentFilter);