大四实习准备5_android广播机制

浏览数：16 / 时间：2015年06月11日

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

 1 package com.example.broadcasttest;
 2 
 3 import android.app.Activity;
 4 import android.content.BroadcastReceiver;
 5 import android.content.Context;
 6 import android.content.Intent;
 7 import android.content.IntentFilter;
 8 import android.net.ConnectivityManager;
 9 import android.net.NetworkInfo;
10 import android.os.Bundle;
11 import android.view.Menu;
12 import android.view.MenuItem;
13 import android.widget.Toast;
14 
15 public class MainActivity extends Activity {
16     private IntentFilter intentFilter;
17     private NetworkChangeReceiver  networkChangeReceiver;
18     @Override
19     protected void onCreate(Bundle savedInstanceState) {
20         super.onCreate(savedInstanceState);
21         setContentView(R.layout.activity_main);
22         intentFilter = new IntentFilter();
23         intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
24         networkChangeReceiver = new NetworkChangeReceiver();
25         registerReceiver(networkChangeReceiver,intentFilter);
26     }
27     
28     @Override
29     protected void onDestroy() {
30         // TODO Auto-generated method stub
31         super.onDestroy();
32         unregisterReceiver(networkChangeReceiver);
33     }
34     
35     class NetworkChangeReceiver extends BroadcastReceiver{//非静态内部类
36 
37         @Override
38         public void onReceive(Context arg0, Intent arg1) {
39             // TODO Auto-generated method stub
40             ConnectivityManager connectivityManager = (ConnectivityManager)
41                     getSystemService(Context.CONNECTIVITY_SERVICE);
42             NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
43             if( networkInfo != null && networkInfo.isAvailable() ){
44                 Toast.makeText(arg0, "network is availbale", Toast.LENGTH_SHORT).show();
45             }else{
46                 Toast.makeText(arg0, "network is unavailbale", Toast.LENGTH_SHORT).show();
47             }
48         }
49         
50     }
51 }

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(?)

 1 package com.example.broadtest2;
 2 
 3 import android.content.BroadcastReceiver;
 4 import android.content.Context;
 5 import android.content.Intent;
 6 import android.widget.Toast;
 7 
 8 public class BootCompleted extends BroadcastReceiver{
 9 
10     @Override
11     public void onReceive(Context arg0, Intent arg1) {
12         // TODO Auto-generated method stub
13             Toast.makeText(arg0, "开机啦",Toast.LENGTH_SHORT).show();
14     }
15 }

BootCompleted.class 广播接收器

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
 3     package="com.example.broadtest2"
 4     android:versionCode="1"
 5     android:versionName="1.0" >
 6 
 7     <uses-sdk
 8         android:minSdkVersion="8"
 9         android:targetSdkVersion="20" />
10 
11     <application
12         android:allowBackup="true"
13         android:icon="@drawable/ic_launcher"
14         android:label="@string/app_name"
15         android:theme="@style/AppTheme" >
16         <activity
17             android:name=".MainActivity"
18             android:label="@string/app_name" >
19             <intent-filter>
20                 <action android:name="android.intent.action.MAIN" />
21 
22                 <category android:name="android.intent.category.LAUNCHER" />
23             </intent-filter>
24         </activity>
25         <receiver 
26             android:name=".BootCompleted" >
27             <intent-filter> 
28                  <action android:name="android.intent.action.BOOT_COMPLETED" />   
29             </intent-filter>
30         </receiver>
31     </application>
32     <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>
33 </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

1 Intent intent = new Intent("lalala");//自定义的广播名
2 intent.putExtra("key", "get lalala BroadCast~");//可以附带些数据
3 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。

 1 package com.example.broadcasttest;
 2 
 3 import android.app.Activity;
 4 import android.content.Intent;
 5 import android.os.Bundle;
 6 import android.view.Menu;
 7 import android.view.MenuItem;
 8 import android.view.View;
 9 import android.view.View.OnClickListener;
10 import android.widget.Button;
11 
12 public class MainActivity extends Activity {
13 
14     Button bt; 
15     @Override
16     protected void onCreate(Bundle savedInstanceState) {
17         super.onCreate(savedInstanceState);
18         setContentView(R.layout.activity_main);
19         bt = (Button) findViewById(R.id.button1);
20         bt.setOnClickListener(new OnClickListener() {
21             
22             @Override
23             public void onClick(View arg0) {
24                 // TODO Auto-generated method stub
25                 Intent intent = new Intent("lalala");
26                 intent.putExtra("key", "get lalala BroadCast~");
27                 sendBroadcast(intent);
28             }
29         });
30     }
31 }

MainActivity.class

 1 package com.example.broadcasttest;
 2 
 3 import android.content.BroadcastReceiver;
 4 import android.content.Context;
 5 import android.content.Intent;
 6 import android.widget.Toast;
 7 
 8 public class diy_broadcastReceiver extends BroadcastReceiver{
 9 
10     @Override
11     public void onReceive(Context arg0, Intent arg1) {
12         // TODO Auto-generated method stub
13         String s = arg1.getExtras().getString("key");//或者arg1.getStringExtra("key");
14         Toast.makeText(arg0, s, Toast.LENGTH_SHORT).show();
15     }
16 
17 }

diy_broadcastReceiver.class

 1 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 2     xmlns:tools="http://schemas.android.com/tools"
 3     android:layout_width="match_parent"
 4     android:layout_height="match_parent"
 5     tools:context="${relativePackage}.${activityClass}" >
 6 
 7     <TextView
 8         android:id="@+id/textView1"
 9         android:layout_width="wrap_content"
10         android:layout_height="wrap_content"
11         android:text="@string/hello_world" />
12 
13     <Button
14         android:id="@+id/button1"
15         android:layout_width="match_parent"
16         android:layout_height="wrap_content"
17         android:layout_alignParentLeft="true"
18         android:layout_below="@+id/textView1"
19         android:layout_marginTop="19dp"
20         android:text="Send BroadCast" />
21 
22 </RelativeLayout>

activity_main.xml

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
 3     package="com.example.broadcasttest"
 4     android:versionCode="1"
 5     android:versionName="1.0" >
 6 
 7     <uses-sdk
 8         android:minSdkVersion="8"
 9         android:targetSdkVersion="20" />
10 
11     <application
12         android:allowBackup="true"
13         android:icon="@drawable/ic_launcher"
14         android:label="@string/app_name"
15         android:theme="@style/AppTheme" >
16         <activity
17             android:name=".MainActivity"
18             android:label="@string/app_name" >
19             <intent-filter>
20                 <action android:name="android.intent.action.MAIN" />
21 
22                 <category android:name="android.intent.category.LAUNCHER" />
23             </intent-filter>
24         </activity>
25         <receiver
26             android:name=".diy_broadcastReceiver" >
27             <intent-filter>
28                 <action android:name="lalala" />
29             </intent-filter>            
30         </receiver>
31     </application>
32 
33 </manifest>