大四实习准备5_android广播机制

2015-5-1

android 广播机制

5.1简介

分为标准广播(Normal broadcasts)(无先后顺序，几乎同时接收，不可截断)和有序广播(Ordered broadcasts)(有先后顺序，可以截断)两种。

5.2接收系统广播

广播接收器对感兴趣的广播进行注册，这样就能监听到对应的广播，并在内部处理相应的逻辑。

注册广播的方式有两种，分别为在代码中注册(动态注册)(缺点：必须在程序启动之后才能接收到广播，因为注册的逻辑是写在onCreat()方法中的)和在AndroidManifest.xml(静态注册)中注册。

创建广播接收器的方法为：新建一个继承自BroadcastReceiver的类，并重写父类的onReceive()方法就行了，监听到广播时对应的处理逻辑就在onReceive()方法中。

5.2.1通过动态注册的方法实现监听网络变化

IntentFilter:组件告诉Android系统自己乐意接收哪些隐式intent(显式的Intent会直接传送到目标组件)

http://blog.csdn.net/today520/article/details/7000048

 package com.example.broadcasttest;

 import android.app.Activity;
 import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.net.ConnectivityManager;
 import android.net.NetworkInfo;
 import android.os.Bundle;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.widget.Toast;

 public class MainActivity extends Activity {
     private IntentFilter intentFilter;
     private NetworkChangeReceiver  networkChangeReceiver;
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         intentFilter = new IntentFilter();
         intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
         networkChangeReceiver = new NetworkChangeReceiver();
         registerReceiver(networkChangeReceiver,intentFilter);
     }

     @Override
     protected void onDestroy() {
         // TODO Auto-generated method stub
         super.onDestroy();
         unregisterReceiver(networkChangeReceiver);
     }

     class NetworkChangeReceiver extends BroadcastReceiver{//非静态内部类

         @Override
         public void onReceive(Context arg0, Intent arg1) {
             // TODO Auto-generated method stub
             ConnectivityManager connectivityManager = (ConnectivityManager)
                     getSystemService(Context.CONNECTIVITY_SERVICE);
             NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
             if( networkInfo != null && networkInfo.isAvailable() ){
                 Toast.makeText(arg0, "network is availbale", Toast.LENGTH_SHORT).show();
             }else{
                 Toast.makeText(arg0, "network is unavailbale", Toast.LENGTH_SHORT).show();
             }
         }

     }
 }

MainActivity.class

需在在AndroidManifest.xml中声明

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

5.2.2通过静态注册监听开机启动广播

//开机启动广播只能用静态注册来监听(?)

 package com.example.broadtest2;

 import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
 import android.widget.Toast;

 public class BootCompleted extends BroadcastReceiver{

     @Override
     public void onReceive(Context arg0, Intent arg1) {
         // TODO Auto-generated method stub
             Toast.makeText(arg0, "开机啦",Toast.LENGTH_SHORT).show();
     }
 }

BootCompleted.class 广播接收器

 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.example.broadtest2"
     android:versionCode="1"
     android:versionName="1.0" >

     <uses-sdk
         android:minSdkVersion="8"
         android:targetSdkVersion="20" />

     <application
         android:allowBackup="true"
         android:icon="@drawable/ic_launcher"
         android:label="@string/app_name"
         android:theme="@style/AppTheme" >
         <activity
             android:name=".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=".BootCompleted" >
             <intent-filter>
                  <action android:name="android.intent.action.BOOT_COMPLETED" />
             </intent-filter>
         </receiver>
     </application>
     <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>
 </manifest>

AndroidManifest.xml 这里需对开机启动做权限声明&静态注册广播

这里MainActivity.class中不用写跟广播有关系的内容。

5.3发送自定义广播

5.3.1发送标准广播

 Intent intent = new Intent("lalala");//自定义的广播名
 intent.putExtra("key", "get lalala BroadCast~");//可以附带些数据
 sendBroadcast(intent);

例子：采用静态注册的方法，点击按钮发送一个自定义的广播，MainActivity中就是发送了下广播，没有直接涉及到diy_broadcastReceiver.class。

 package com.example.broadcasttest;

 import android.app.Activity;
 import android.content.Intent;
 import android.os.Bundle;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.Button;

 public class MainActivity extends Activity {

     Button bt;
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         bt = (Button) findViewById(R.id.button1);
         bt.setOnClickListener(new OnClickListener() {

             @Override
             public void onClick(View arg0) {
                 // TODO Auto-generated method stub
                 Intent intent = new Intent("lalala");
                 intent.putExtra("key", "get lalala BroadCast~");
                 sendBroadcast(intent);
             }
         });
     }
 }

MainActivity.class

 package com.example.broadcasttest;

 import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
 import android.widget.Toast;

 public class diy_broadcastReceiver extends BroadcastReceiver{

     @Override
     public void onReceive(Context arg0, Intent arg1) {
         // TODO Auto-generated method stub
         String s = arg1.getExtras().getString("key");//或者arg1.getStringExtra("key");
         Toast.makeText(arg0, s, Toast.LENGTH_SHORT).show();
     }

 }

diy_broadcastReceiver.class

 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     tools:context="${relativePackage}.${activityClass}" >

     <TextView
         android:id="@+id/textView1"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:text="@string/hello_world" />

     <Button
         android:id="@+id/button1"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_alignParentLeft="true"
         android:layout_below="@+id/textView1"
         android:layout_marginTop="19dp"
         android:text="Send BroadCast" />

 </RelativeLayout>

activity_main.xml

 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.example.broadcasttest"
     android:versionCode="1"
     android:versionName="1.0" >

     <uses-sdk
         android:minSdkVersion="8"
         android:targetSdkVersion="20" />

     <application
         android:allowBackup="true"
         android:icon="@drawable/ic_launcher"
         android:label="@string/app_name"
         android:theme="@style/AppTheme" >
         <activity
             android:name=".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=".diy_broadcastReceiver" >
             <intent-filter>
                 <action android:name="lalala" />
             </intent-filter>
         </receiver>
     </application>

 </manifest>

AndroidManifest.xml

别的应用，如果静态注册了同样的广播，也会进行相应的操作。

问题：

一个广播接收器注册了多个广播，怎样根据广播来源的不同，进行不同的操作？

5.3.2发送有序广播

//..........