安卓BroadcastReceiver組件使用系列3：使用廣播來判斷數據網絡和無線網絡的連接情況

註冊廣播的兩種方式：1.使用Context.registerReceiver()     2.使用<receiver>在AndroidManifest.xml(清單文件)中註冊

註冊廣播的時候在Activity.onResume()中註冊，在Activity.onPause()中卸載

下面我們來介紹一下它的使用方法。

整體思路：在activity中的onCreate方法中聲明ConnectivityManager對象，用於判斷網絡的狀況，聲明NotificationManager對象，用於發送狀態欄通知，實例化一個BroadcastReceiver對象，在這個對象的onReceive方法中判斷網絡鏈接情況，如果數據網絡和無線網絡都沒有連接，則彈出網絡異常的狀態欄通知。在onCreate方法中實例化ConnectivityManager對象和NotificationManager對象，在onResume方法中註冊廣播，在onPause方法中卸載廣播。注意在清單文件AndroidManifest.xml中添加網絡授權。

MainActivity.java文件：

package com.example.android_broadcast_state;

import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.Notification.Builder;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.view.Menu;

public class MainActivity extends Activity {

    private ConnectivityManager manager;//判斷網絡的狀況
    private NotificationManager notificationManager;//需要通知去提醒用戶

    private BroadcastReceiver receiver=new BroadcastReceiver() {
		
		@SuppressLint("NewApi") @Override
		public void onReceive(Context context, Intent intent) {
			// TODO Auto-generated method stub
//			提醒用戶網絡狀況有異常
//			分別獲得2G和3G、wifi的網絡信號
//			廣播中提醒用戶的兩種方式：土司、通知
			NetworkInfo mobileInfo=manager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
			NetworkInfo wifiInfo=manager.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
			if(!mobileInfo.isConnected()||!wifiInfo.isConnected()){
				Notification.Builder builder=new Notification.Builder(MainActivity.this);
				builder.setContentText("提示信息");
				builder.setContentText("網絡狀況有異常！");
				builder.setSmallIcon(R.drawable.ic_launcher);
				notificationManager.notify(1001,builder.build());
			}
			
		}
	};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        manager=(ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
        notificationManager=(NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE);
    }
    
//  註冊廣播
    @Override
    protected void onResume() {
    	// TODO Auto-generated method stub
    	super.onResume();
    	IntentFilter filter=new IntentFilter();
    	filter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
    	registerReceiver(receiver, filter);
    }
    
//  卸載廣播
    @Override
    protected void onPause() {
    	// TODO Auto-generated method stub
    	super.onPause();
    	if(receiver!=null){
    		unregisterReceiver(receiver);
    	}
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
    
}

AndroidManifest.xml文件：

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

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />
    
<!-- 添加網絡授權 -->
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE"/>

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.android_broadcast_state.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>
    </application>

</manifest>