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17_Android中Broadcast详解(有序播音，无序广播)最终广播,Bundle传递参数，传递参数的时候指定权限

分类: IT文章 • 2024-01-31 23:13:06
17_Android中Broadcast详解(有序广播，无序广播)最终广播,Bundle传递参数，传递参数的时候指定权限


1  Broadcast是Android中的四大组件之一，他的用途很大，比如系统的一些广播：电量低、开机、锁屏等一些操作都会发送一个广播。

2  广播被分为两种不同的类型：“普通广播（Normalbroadcasts）”和“有序广播(Ordered broadcasts)”.普通广播是完全异步的，可以在同一时刻(逻辑上)被所有广播接收者接收到，消息传递的效率比较高，但缺点是：接收者不能将处理结果传递给下一个接收者，并且无法终止广播Intent的传播；然后有序广播是按照接收者声明的优先级别(声明在intent-filter元素的android:priority)属性中，数越大优先级别越高，取值范围：-1000到1000。也可以调用IntentFilter对象的setPriority()进行设置），被接收者依次接收广播。如：A的级别高于B,B的级别高于C,那么，广播先传A，在传给B，最后传给C，A得到广播后，可以往广播里存入数据，当广播传给B时，B可以从广播中得到A存入的数据。

 

Context.sendBroadcast()

发送的是普通广播，所有订阅者都有机会获得并进行处理。

Context.sendOrderedBroadcast()

发送的是有序广播，系统会根据接收者声明的优先级按顺序逐个执行接收者，前面的接收者有权终止广播（通过调用BroadcastReceiver.abortBroadcast()），如果广播被前面的接收者终止，后面的接收者就再也无法获取到广播。对于有序广播，前面的接收者可以将处理结果存进广播Intent，然后传给下一个接收者。

 

编写以下案例：

17_Android中Broadcast详解(有序播音，无序广播)最终广播,Bundle传递参数，传递参数的时候指定权限

3 编写Android清单文件

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.itheima.broadcasttest"

    android:versionCode="1"

    android:versionName="1.0" >

 

    <uses-sdk

        android:minSdkVersion="8"

        android:targetSdkVersion="19" />

 

    <application

        android:allowBackup="true"

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name"

        android:theme="@style/AppTheme" >

        <activity

            android:name="com.itheima.broadcasttest.MainActivity"

            android:label="@string/app_name" >

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

 

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

       

        <receiver android:name="com.itheima.broadcasttest.Level1Receiver" >

            <intent-filter android:priority="1000" >

                <action android:name="com.itheima.broadcasttest.songwennuan" />

            </intent-filter>

        </receiver>

        <receiver android:name="com.itheima.broadcasttest.Level2Receiver" >

            <intent-filter android:priority="500" >

                <action android:name="com.itheima.broadcasttest.songwennuan" />

            </intent-filter>

        </receiver>

        <receiver android:name="com.itheima.broadcasttest.Level3Receiver" >

            <intent-filter android:priority="100" >

                <action android:name="com.itheima.broadcasttest.songwennuan" />

            </intent-filter>

        </receiver>

        <receiver android:name="com.itheima.broadcasttest.FinalReceiver" >

            <intent-filter android:priority="0" >

                <action android:name="com.itheima.broadcasttest.songwennuan" />

            </intent-filter>

        </receiver>

    </application>

 

</manifest>

4 编写布局文件activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:orientation="vertical"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    tools:context=".MainActivity" >

   

    <Button

        android:onClick="send1"

        android:layout_width="fill_parent"

        android:layout_height="wrap_content"

        android:text="发送无序广播" />

 

    <Button

        android:onClick="send2"

        android:layout_width="fill_parent"

        android:layout_height="wrap_content"

        android:text="发送有序广播" />

   

</LinearLayout>

5 编写一下广播接收者

Level1Receiver

package com.itheima.broadcasttest;

 

import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.util.Log;

 

public class Level1Receiver extends BroadcastReceiver {

         private static final String TAG = "Broadcasttest";

        

         @Override

         public void onReceive(Context context, Intent intent) {

                   String message = getResultData();

                   Log.i(TAG,"省级部门得到*的消息:" + message);

                   abortBroadcast();  //这里是终止了消息,可以关闭或者取消这里查看LogCat中打印的效果。

                   setResultData("给农民兄弟发5000块钱");

         }

 

}

Level2Receiver

package com.itheima.broadcasttest;

 

import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.util.Log;

 

public class Level2Receiver extends BroadcastReceiver {

         private static final String TAG = "Broadcasttest";

        

         @Override

         public void onReceive(Context context, Intent intent) {

                   String message = getResultData();

                   Log.i(TAG,"市级部门得到省级的消息"  + message);

                   setResultData("给农民兄弟发2000块钱");

         }

 

}

Level3Receiver

package com.itheima.broadcasttest;

 

import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.util.Log;

 

public class Level3Receiver extends BroadcastReceiver {

         private static final String TAG = "Broadcasttest";

        

         @Override

         public void onReceive(Context context, Intent intent) {

                   String message = getResultData();

                   Log.i(TAG, "乡级部门得到市的消息：" + message);

                   setResultData("给农民兄弟发两大大米");

         }

 

}

FinalReceiver

package com.itheima.broadcasttest;

 

import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.util.Log;

 

public class FinalReceiver extends BroadcastReceiver {

         private static final String TAG = "Broadcasttest";

        

         @Override

         public void onReceive(Context context, Intent intent) {

                   String message = getResultData();

                   Log.i(TAG, "农民兄弟得到乡的消息：" + message);

         }

}

6 MainActivity的内容如下：

package com.itheima.broadcasttest;

 

import android.content.Intent;

import android.os.Bundle;

import android.support.v7.app.ActionBarActivity;

import android.view.View;

 

public class MainActivity extends ActionBarActivity {

 

         @Override

         protected void onCreate(Bundle savedInstanceState) {

                   super.onCreate(savedInstanceState);

                   setContentView(R.layout.activity_main);

         }

 

         /**

          * 发送无序广播

          * @param view

          */

         public void send1(View view) {

                   Intent intent = new Intent();

                   intent.setAction("com.itheima.broadcasttest.songwennuan");

                   intent.putExtra("msg", "发1万块");

                   //无序广播，不可被拦截，不可终止

                   sendBroadcast(intent);

         }

        

         public void send2(View view) {

                   Intent intent = new Intent();

                   intent.setAction("com.itheima.broadcasttest.songwennuan");

                   //有序广播，可被拦截，可终止，可以修改数据

                   sendOrderedBroadcast(intent, null,new FinalReceiver(),null,0,"给农民兄弟发10000块钱",null);

         }

}

运行：

17_Android中Broadcast详解(有序播音，无序广播)最终广播,Bundle传递参数，传递参数的时候指定权限

点击”发送无序广播”按钮，在LogCat中打印出的内容如下：

17_Android中Broadcast详解(有序播音，无序广播)最终广播,Bundle传递参数，传递参数的时候指定权限

点击” 发送有序广播”按钮，在LogCat中打印出的内容如下：

17_Android中Broadcast详解(有序播音，无序广播)最终广播,Bundle传递参数，传递参数的时候指定权限

之所以在Level1Receiver执行了abortBroadcast()后还显示下面一条，是因为指定了之中广播：

//有序广播，可被拦截，可终止，可以修改数据

sendOrderedBroadcast(intent, null,new FinalReceiver(),null,0,"给农民兄弟发10000块钱",null);

若把Level1Receiver改成如下时：

package com.itheima.broadcasttest;

 

import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.util.Log;

 

public class Level1Receiver extends BroadcastReceiver {

         private static final String TAG = "Broadcasttest";

        

         @Override

         public void onReceive(Context context, Intent intent) {

                   String message = getResultData();

                   Log.i(TAG,"省级部门得到*的消息:" + message);

                   //abortBroadcast();  //这里是终止了消息,可以关闭或者取消这里查看LogCat中打印的效果。

                   setResultData("给农民兄弟发5000块钱");

         }

}

点击”发送有序广播”后显示的内容如下：

17_Android中Broadcast详解(有序播音，无序广播)最终广播,Bundle传递参数，传递参数的时候指定权限

==========================================================================

关于有序广播的另外的一个案例：

17_Android中Broadcast详解(有序播音，无序广播)最终广播,Bundle传递参数，传递参数的时候指定权限

1、编写第一个广播MyOrderBroadcastReciver

package com.demoorderbroadcast;

 

import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.os.Bundle;

import android.util.Log;

 

public class MyOrderBroadcastReciver extends BroadcastReceiver {

 

         private static final String TAG = "BroadCast";

        

         @Override

         public void onReceive(Context context, Intent intent) {

                   String strMsg = intent.getStringExtra("msg");

                   Log.i(TAG, "第一个:" + strMsg);

                   //通过Bundle传递参数

                   Bundle extras = new Bundle();

                   extras.putString("msg", "第一个界面传过来的" + strMsg);

                   setResultExtras(extras);//继续向下传

         }

}

2 编写第二个广播MyOrderBroadcastReciverTwo

package com.demoorderbroadcast;

 

import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.os.Bundle;

import android.util.Log;

 

public class MyOrderBroadcastReciverTwo extends BroadcastReceiver {

 

         private static final String TAG = "BroadCast";

        

         @Override

         public void onReceive(Context context, Intent intent) {

                   //abortBroadcast();  //开启此处，可以截断广播，不让它传到third中

                   String strMsg = intent.getStringExtra("msg");   //获取广播的原始数据

                  

                   Log.i(TAG, "第二个界面传过来的" + strMsg);

                   Bundle extras = new Bundle();

                   extras.putString("msg", "第二个界面传过来的" + strMsg);

                   setResultExtras(extras); //继续向下传

                  

                   //"第二个:"+strMsg这是two中新的数据，传递到third中,

                   //在third中是用getResultData来获得setResultData("")中的数据

                   setResultData("第二个：" + strMsg);

         }

        

}

3 编写第三个广播MyOrderBroadcastReciverThird

package com.demoorderbroadcast;

 

import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.os.Bundle;

import android.util.Log;

 

public class MyOrderBroadcastReciverThird extends BroadcastReceiver {

    private static final String TAG = "BroadCast";

   

    @Override

    public void onReceive(Context context, Intent intent) {

       //获得two中setResultData中的数据

       String resultData = getResultData();

       //获取two中setResultExtras中的数据

       Bundle bundle = getResultExtras(true);

       //获取广播的原始数据

       String bundleData = bundle.getString("msg");

      

       //获取广播的原始数据

       String strMsg = intent.getStringExtra("msg");

       Log.i(TAG, "第三个：" + strMsg);

      

       Log.i(TAG,"two中传递到third新的数据：" + resultData);

       Log.i(TAG, "two中setResultExtras(extras)传到third新的数据：" + bundleData);

    }

}

4 编写MainActivity，代码如下：

package com.demoorderbroadcast;

 

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;

 

public class MainActivity extends Activity {

 

         private Button btnSendOrderBroadCast;

        

         protected void onCreate(Bundle savedInstanceState) {

                   super.onCreate(savedInstanceState);

                   setContentView(R.layout.activity_main);

                   initView();

         }

        

         private void initView() {

                   btnSendOrderBroadCast = (Button) this.findViewById(R.id.btn);

                   btnSendOrderBroadCast.setOnClickListener(new MyOnclickListener());

         }

 

         private class MyOnclickListener implements OnClickListener {

 

                   public void onClick(View v) {

                            if (btnSendOrderBroadCast==v) {

                                     sendOrderBroadCast();

                            }

                   }

         }

 

         public void sendOrderBroadCast() {

                   Intent intent = new Intent("com.pzf.mybroadcast");

                   intent.putExtra("msg", "toto ni hao");

                   sendOrderedBroadcast(intent, "com.pzf.permission");

         }

}

5 编写Android的清单文件AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.demoorderbroadcast"

    android:versionCode="1"

    android:versionName="1.0" >

 

    <uses-sdk

        android:minSdkVersion="8"

        android:targetSdkVersion="19" />

    <permission android:name="com.pzf.permission" android:protectionLevel="normal"></permission>

    <uses-permission android:name="com.pzf.permission"/>

   

    <application

        android:allowBackup="true"

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name"

        android:theme="@style/AppTheme" >

        <activity

            android:name="com.demoorderbroadcast.MainActivity"

            android:label="@string/app_name" >

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

 

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

        <receiver android:name="com.demoorderbroadcast.MyOrderBroadcastReciver">

            <intent-filter android:priority="1000">

                <action android:name="com.pzf.mybroadcast"></action>

            </intent-filter>

        </receiver>

        <receiver android:name="com.demoorderbroadcast.MyOrderBroadcastReciverTwo">

            <intent-filter android:priority="900">

                <action android:name="com.pzf.mybroadcast"></action>

            </intent-filter>

        </receiver>

        <receiver android:name="com.demoorderbroadcast.MyOrderBroadcastReciverThird">

            <intent-filter android:priority="800">

                <action android:name="com.pzf.mybroadcast"></action>

            </intent-filter>

        </receiver>

    </application>

</manifest>

当点击“发送有序广播”时，LogCat中打印的内容如下：

17_Android中Broadcast详解(有序播音，无序广播)最终广播,Bundle传递参数，传递参数的时候指定权限

 

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