Android 广播(Broadcast)
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!\n"+string, Toast.LENGTH_SHORT).show(); } }
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