Android-动态注册广播和注销广播
Android-动态注册广播和注销广播
静态注册广播
广播机制在安卓开发很常见也很重要，它既可以静态注册，也可以
动态注册和注销，广播可以设置优先级。
首先是静态
activity_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" >
<Button android:id="@+id/btnSend" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="发送广播" />
LinearLayout>
设置一个按钮用于发送广播
创建一个广播类AgainMyReceiver.java继承BroadcastReceiver
AgainMyReceiver.java
package com.xieth.as.againbroadcastreceiver;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
public class AgainMyReceiver extends BroadcastReceiver {
public AgainMyReceiver() {
}
@Override
public void onReceive(Context context, Intent intent) {
Log.d("AgainMyReceiver", "静态广播接收到了消息");
}
}
打印日志便于测试查看，然后在AndroidManifest.xml修改
<receiver android:name=".AgainMyReceiver" android:enabled="true" android:exported="true" >
receiver>然后在MainActivity.java定义事件
MainActivity.java
package com.xieth.as.againbroadcastreceiver;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private Intent it = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
findViewById(R.id.btnSend).setOnClickListener(this);
it= new Intent(MainActivity.this, AgainMyReceiver.class);
}
@Override
public void onClick(View v) {
int id = v.getId();
switch (id) {
case R.id.btnSend:
sendBroadcast(it);
break;
default:
break;
}
}
}
运行输出：
点击发送广播按钮
成功接收到广播消息
动态发送广播和注销广播
在这之前把下面这一段删除：
<receiver android:name=".AgainMyReceiver" android:enabled="true" android:exported="true" >
receiver>然后在布局文件添加两个按钮用于注册和注销广播：
activity_main.xml
"http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
>
接着在广播类添加此字段：
public static final String ACTION = "com.xieth.as.againbroadcastreceiver.action.intent.AgainMyReceiver"MainActivity.java
package com.xieth.as.againbroadcastreceiver;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private AgainMyReceiver myReceiver = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
findViewById(R.id.btnSend).setOnClickListener(this);
findViewById(R.id.btnReg).setOnClickListener(this);
findViewById(R.id.btnUnreg).setOnClickListener(this);
}
@Override
public void onClick(View v) {
int id = v.getId();
switch (id) {
case R.id.btnSend:
Intent i = new Intent(AgainMyReceiver.ACTION);
sendBroadcast(i);
break;
case R.id.btnReg:
//注册广播
if (myReceiver == null) {
myReceiver = new AgainMyReceiver();
registerReceiver(myReceiver, registerReceiver(myReceiver, new IntentFilter(myReceiver.ACTION)););
}
break;
case R.id.btnUnreg:
//注销广播
if (myReceiver != null) {
unregisterReceiver(myReceiver);
myReceiver = null;
}
break;
default:
break;
}
}
}
运行效果：
刚开始点击发送广播，没有输出信息，所以我们在此注册广播，然后再点击发送广播：
广播的优先级
再次新建一个广播类，命名为AgainMyReceiver1.java
package com.xieth.as.againbroadcastreceiver;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
public class AgainMyReceiver1 extends BroadcastReceiver {
public AgainMyReceiver1() {
}
@Override
public void onReceive(Context context, Intent intent) {
Log.d("AgainMyReceiver", "AgainMyReceiver1接收到了消息");
}
}
AgainMyReceiver.java
package com.xieth.as.againbroadcastreceiver;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
public class AgainMyReceiver extends BroadcastReceiver {
public static final String ACTION = "com.xieth.as.againbroadcastreceiver.action.intent.AgainMyReceiver";
public AgainMyReceiver() {
}
@Override
public void onReceive(Context context, Intent intent) {
Log.d("AgainMyReceiver", "AgainMyReceiver接收到了消息");
}
}
然后修改AndroidManifest.xml文件
<receiver android:name=".AgainMyReceiver1" android:enabled="true" android:exported="true" >
<intent-filter>
<action android:name="com.xieth.as.againbroadcastreceiver.action.intent.AgainMyReceiver">action>
intent-filter>
receiver>
<receiver android:name=".AgainMyReceiver" android:enabled="true" android:exported="true" >
<intent-filter>
<action android:name="com.xieth.as.againbroadcastreceiver.action.intent.AgainMyReceiver">action>
intent-filter>
receiver>先不设置优先级,观察输出结果：
由于action是一样的，所以同时接收到了消息，现在设置优先级，修改AndroidManifest.xml文件
<receiver android:name=".AgainMyReceiver1" android:enabled="true" android:exported="true" >
<intent-filter android:priority="1">
<action android:name="com.xieth.as.againbroadcastreceiver.action.intent.AgainMyReceiver">action>
intent-filter>
receiver>
<receiver android:name=".AgainMyReceiver" android:enabled="true" android:exported="true" >
<intent-filter android:priority="2">
<action android:name="com.xieth.as.againbroadcastreceiver.action.intent.AgainMyReceiver">action>
intent-filter>
receiver>然后运行输出：
可以看到AgainMyReceiver优先接收到消息，因为优先级为2，比AgainMyReceiver1的优先级高。
中断广播的发送
我们可以中断广播的发送：
但是发送的方式不一样：是sendOrderedBroadcast()方式发送
修改代码：
case R.id.btnSend:
Intent i = new Intent(AgainMyReceiver.ACTION);
sendOrderedBroadcast(i, null);
// sendBroadcast(i);
break;然后在AgianMyReceiver加入如下代码终止比它优先级低发送广播
使用abortBroadcast()方法
其他不做修改！
@Override
public void onReceive(Context context, Intent intent) {
Log.d("AgainMyReceiver", "AgainMyReceiver接收到了消息");
abortBroadcast();
}运行输出：
可以看见成功终止了向AgainMyReceiver1发送广播！
2016年1月13日12:22:45 记录