本次案例要实现的功能是拦截一条有序广播。通过send()OrderedBroadcast()方法发送一条有序广播。
并运行程序:
1:程序启动后,单击“发送有序广播”按钮,发出一条广播事件,此时观察LogCat窗口下的提示信息
2:若将广播接收者MyBroadcastReceiverTwo优先级同样设置为1000,并将MyBroadcastReceiverTwo注册在MyBroadcastReceiverOne前面,再来运行程序
3:修改MyBroadcastReceiverTwo如下
最终要得到的运行结果如下图:
1.首先在目录app/res/drawable中粘贴图片stitch_one.png作为背景图。
2.创建布局文件activity_main.xml,内容如下:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/stitch_one"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.administrator.oderedbroadcast.MainActivity">
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_marginTop="80dp"
android:onClick="send"
android:text="发送有序广播"
android:paddingLeft="5dp"
android:paddingRight="5dp"
android:background="#FBFBFF"
android:textSize="20sp"/>
</RelativeLayout>
3.编写界面交互代码(MainActivity.java),代码如下:
package com.example.administrator.oderedbroadcast;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void send(View view){
Intent intent=new Intent();
//定义广播的时间类型
intent.setAction("Intercept_Stitch");
//发送广播
sendOrderedBroadcast(intent,null);
}
}
4.创建广播接收者,具体步骤如下图:
MyBroadcastReceiverOne中的代码如下:
package com.example.administrator.oderedbroadcast;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
public class MyBroadcastReceiverOne extends BroadcastReceiver {
public MyBroadcastReceiverOne() {
}
@Override
public void onReceive(Context context, Intent intent) {
// TODO: This method is called when the BroadcastReceiver is receiving
// an Intent broadcast.
Log.i("MyBroadcastReceiverOne","自定义的广播接收者One,接收到了广播事件");
}
}
5.配置清单文件AndroidManifest.xml,代码如下:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.administrator.oderedbroadcast">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<receiver
android:name=".MyBroadcastReceiverOne"
android:enabled="true"
android:exported="true">
<intent-filter android:priority="1000">
<action android:name="Intercept_Stitch" />
</intent-filter>
</receiver>
</application>
</manifest>
运行结果如下图:
窗口下的提示信息如下图:
6.再次创建广播接收者MyBroadcastReceiverTwo,代码如下:
package com.example.administrator.oderedbroadcast;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
public class MyBroadcastReceiverTwo extends BroadcastReceiver {
public MyBroadcastReceiverTwo() {
}
@Override
public void onReceive(Context context, Intent intent) {
// TODO: This method is called when the BroadcastReceiver is receiving
// an Intent broadcast.
Log.i("MyBroadcastReceiverTwo","自定义的广播接收者Two,接收到了广播事件");
}
}
要将广播接收者MyBroadcastReceiverTwo优先级同样设置为1000,并将MyBroadcastReceiverTwo注册在MyBroadcastReceiverOne前面,则修改清单文件AndroidManifest.xml,内容为:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.administrator.oderedbroadcast">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<receiver
android:name=".MyBroadcastReceiverTwo"
android:enabled="true"
android:exported="true">
<intent-filter android:priority="1000">
<action android:name="Intercept_Stitch" />
</intent-filter>
</receiver
<receiver
android:name=".MyBroadcastReceiverOne"
android:enabled="true"
android:exported="true">
<intent-filter android:priority="1000">
<action android:name="Intercept_Stitch" />
</intent-filter>
</receiver>
>
</application>
</manifest>
运行后,窗口提示词如下图:
7.修改MyBroadcastReceiverTwo之后,代码如下:
package com.example.administrator.oderedbroadcast;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
public class MyBroadcastReceiverTwo extends BroadcastReceiver {
public MyBroadcastReceiverTwo() {
}
@Override
public void onReceive(Context context, Intent intent) {
// TODO: This method is called when the BroadcastReceiver is receiving
// an Intent broadcast.
Log.i("MyBroadcastReceiverTwo","自定义的广播接收者Two,接收到了广播事件");
abortBroadcast();//拦截有序广播
Log.i("MyBroadcastReceiverTwo","我是广播接收者Two,广播被我终结了");
}
}
运行后,窗口提示词如下图:
结论:优先级最高的最先收到广播事件,说明广播接收者的优先级决定广播接收的顺序。高优先级的广播是可以被终止的,在MyBroadcastReceiverTwo添加abortBroadcast()拦截广播。