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一、廣播發(fā)送者&廣播接收者介紹
1.廣播接收者
廣播接收者簡(jiǎn)單地說(shuō)就是接收廣播意圖的Java類(lèi),此Java類(lèi)繼承BroadcastReceiver類(lèi),重寫(xiě):
public void onReceive(Context context,Intent intent),其中intent可以獲得傳遞的數(shù)據(jù);
廣播意圖就是通過(guò)Context.sendBroadcast(Intent intent)或Context.sendOrderedBroadcast(Intent intent)發(fā)送的意圖,通過(guò)這個(gè)語(yǔ)句,能夠廣播給所有滿足條件的組件,比如intent設(shè)置了action="com.xiazdong",則所有在AndroidManifest.xml中設(shè)置過(guò)<action android:name="com.xiazdong"/>的廣播接收者都能夠接收到廣播;
注:onReceive方法必須在10秒內(nèi)完成,如果沒(méi)有完成,則拋“Application No Response”當(dāng)廣播接收者onReceive方法需要執(zhí)行很長(zhǎng)時(shí)間時(shí),最好將此耗時(shí)工作通過(guò)Intent發(fā)送給Service,由Service完成,并且不能使用子線程解決,因?yàn)锽roadcastReceiver是接收到廣播后才創(chuàng)建的,并且生命周期很短,因此子線程可能在沒(méi)有執(zhí)行完就已經(jīng)被殺死了。
public void onReceive(Context context,Intent intent){
Intent intent = new Intent(context,XxxService.class);
context.startService(intent);
}
2.廣播發(fā)送者
通常廣播發(fā)送方就是調(diào)用Context.sendBroadcast()的程序,而廣播接收者就是繼承BroadcastReceiver的程序;
通常廣播發(fā)送方都是通過(guò)隱式意圖,這樣才能發(fā)送給多人;
廣播發(fā)送方分為普通廣播和有序廣播;
普通廣播:發(fā)送方發(fā)出后,幾乎同時(shí)到達(dá)多個(gè)廣播接收者處,某個(gè)接收者不能接收到廣播后進(jìn)行一番處理后傳給下一個(gè)接收者,并且無(wú)法終止廣播繼續(xù)傳播;Context.sendBroadcast(intent);
有序廣播:廣播接收者需要提前設(shè)置優(yōu)先級(jí),優(yōu)先級(jí)高的先接收到廣播,優(yōu)先級(jí)數(shù)值為-1000~1000,在AndroidManifest.xml的<intent-filter android:priority="xxx">設(shè)置;比如存在3個(gè)廣播接收者A、B、C,優(yōu)先級(jí)A>B>C,因此A最先收到廣播,當(dāng)A收到廣播后,可以向廣播中添加一些數(shù)據(jù)給下一個(gè)接收者(intent.putExtra()),或者終止廣播(abortBroadcast());
Context.sendOrderedBroadcast(intent);
二、廣播接收者核心代碼
同步廣播發(fā)送方核心代碼:
Intent intent = new Intent();
intent.setAction("...");
Context.sendBroadcast(intent);
有序廣播發(fā)送方核心代碼:
Intent intent = new Intent();
intent.setAction("...");
Context.sendOrderedBroadcast(intent,null);
廣播接收者核心代碼:
public class Receiver extends BroadcastReceiver{
public void onReceive(Context context, Intent intent) {
Bundle bundle = intent.getExtras();
...
}
}
AndroidManifest.xml
<application>
<receiver android:name=".Receiver">
<intent-filter android:priority="1000">
<action android:name="com.xiazdong"/>
</intent-filter>
</receiver>
</application>
三、廣播實(shí)例
1.同步廣播實(shí)例
(1)廣播發(fā)送者:
package com.xiazdong.broadcastsender;
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;
import android.widget.Toast;
public class MainActivity extends Activity {
private Button button;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
button = (Button)this.findViewById(R.id.button);
button.setOnClickListener(listener);
}
private OnClickListener listener = new OnClickListener(){
@Override
public void onClick(View v) {
Intent intent = new Intent();
intent.setAction("com.xiazdong");
intent.putExtra("name", "xiazdong");
MainActivity.this.sendBroadcast(intent);
Toast.makeText(getApplicationContext(), "發(fā)送廣播成功", Toast.LENGTH_SHORT).show();
}
};
}
(2)廣播接收者
package com.xiazdong.broadcastreceiver1;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
public class Receiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
String name = intent.getExtras().getString("name");
Log.i("Recevier1", "接收到:"+name);
}
}
AndroidManifest.xml
<receiver android:name=".Receiver">
<intent-filter>
<action android:name="com.xiazdong"/>
</intent-filter>
</receiver>
2.有序廣播實(shí)例
場(chǎng)景說(shuō)明:
(1)廣播發(fā)送者
package com.xiazdong.broadcastsender;
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;
import android.widget.Toast;
public class MainActivity extends Activity {
private Button button;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
button = (Button)this.findViewById(R.id.button);
button.setOnClickListener(listener);
}
private OnClickListener listener = new OnClickListener(){
@Override
public void onClick(View v) {
Intent intent = new Intent();
intent.setAction("com.xiazdong");
intent.putExtra("name", "xiazdong");
MainActivity.this.sendOrderedBroadcast(intent, null); //有序廣播發(fā)送
Toast.makeText(getApplicationContext(), "發(fā)送廣播成功", Toast.LENGTH_SHORT).show();
}
};
}
(2)廣播接收者
Receiver1
package com.xiazdong.broadcastreceiver1;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
public class Receiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
String name = intent.getExtras().getString("name");
Log.i("Recevier1", "接收到:"+name);
abortBroadcast(); //Receiver1接收到廣播后中斷廣播
}
}
AndroidManifest.xml
<receiver android:name=".Receiver">
<intent-filter android:priority="1000"> <!-- 設(shè)置最高優(yōu)先級(jí) -->
<action android:name="com.xiazdong"/>
</intent-filter>
</receiver>
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