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>
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
//..........
时间： 2024-10-11 13:28:57