Android-动态注册广播和注销广播

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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：
这里写图片描述
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

<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"        />    <Button        android:id="@+id/btnReg"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="注册广播"        />    <Button        android:id="@+id/btnUnreg"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="注销广播"        /></LinearLayout>

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：
这里写图片描述
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：
这里写图片描述
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"            >            <!--设置优先级-->            <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"            >            <!--设置优先级-->            <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：
这里写图片描述
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：
这里写图片描述
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

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