发送有序广播

本文介绍了一个简单的有序广播案例,展示了如何使用Android系统发送和接收有序广播,并通过调整广播接收者的优先级来改变广播的接收顺序。

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
这里写图片描述

最终要得到的运行结果如下图:
这里写图片描述

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:
这里写图片描述

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:
这里写图片描述
窗口下的提示信息如下图:
这里写图片描述

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:
这里写图片描述

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:
这里写图片描述
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。

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