Android开发之使用广播监听网络状态变化

我们经常需要判断网络状态的变化，如有无网络，所以需要监听网络状态的变化，比如网络断开，网络连接给予友好提示。如何监听网络状态的变化呢，最近工作中需要用到这个，于是就用广播机制来实现了网络状态的监听。

使用广播机制来监听网络状态主要涉及到以下几点：

1.需要自己编写个网络广播接收器，该接收器继承BroadcastReceiver类，用来接收系统发出的广播。比如我自己写了个NetStatusReceiver广播接收器。代码如下：

package com.log.system;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.widget.Toast;


public class NetStatusReceiver  extends BroadcastReceiver{

    public static final int NETSTATUS_INAVAILABLE = 0;
    public static final int NETSTATUS_WIFI = 1;
    public static final int NETSTATUS_MOBILE = 2;
    public static int netStatus = 0;
    public static boolean updateSuccess = false;
    private INetStatusListener mINetStatusListener;

    public void onReceive(Context context, Intent intent) {
        ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo mobileNetInfo = cm.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
        NetworkInfo wifiNetInfo = cm.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
        NetworkInfo allNetInfo = cm.getActiveNetworkInfo();

        if (allNetInfo == null) {
            if (mobileNetInfo != null && (mobileNetInfo.isConnected() || mobileNetInfo.isConnectedOrConnecting())) {
                netStatus = NETSTATUS_MOBILE;
            } else if (wifiNetInfo != null && wifiNetInfo.isConnected() || wifiNetInfo.isConnectedOrConnecting()) {
                netStatus = NETSTATUS_WIFI;
            } else {
                netStatus = NETSTATUS_INAVAILABLE;
            }
        } else {
            if (allNetInfo.isConnected() || allNetInfo.isConnectedOrConnecting()) {
                if (mobileNetInfo.isConnected() || mobileNetInfo.isConnectedOrConnecting()) {
                    netStatus = NETSTATUS_MOBILE;
                } else {
                    netStatus = NETSTATUS_WIFI;
                }
            } else {
                netStatus = NETSTATUS_INAVAILABLE;
            }
        }
        if(mINetStatusListener != null){
            mINetStatusListener.getNetState(netStatus);
        }
//        if (netStatus == NETSTATUS_INAVAILABLE) {
//            Toast.makeText(context, "网络未连接",Toast.LENGTH_SHORT).show();
//        } else if (netStatus == NETSTATUS_MOBILE) {
//            Toast.makeText(context, "网络处于移动网络",Toast.LENGTH_SHORT).show();
//        } else {
//            Toast.makeText(context, "网络处于Wifi网络",Toast.LENGTH_SHORT).show();
//        }
    }
    
    public void setNetStateListener(INetStatusListener listener){
        mINetStatusListener = listener;
    }
    
    public interface INetStatusListener{
        public void getNetState(int state);
    }
}

2.注册广播接收器

首先new一个广播接收器，然后对该接收器进行注册，也就是注册广播，然后并设置监听器。注册广播和设置监听的实现如下：

netReceiver = new NetStatusReceiver();
setRegisterReceiver(netReceiver);
setNetListener();

对应的具体方法实现代码如下：

public void setRegisterReceiver(NetStatusReceiver netReceiver){
        IntentFilter filter = new IntentFilter();
        filter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
        registerReceiver(netReceiver, filter);
    }
    public void setNetListener(){
        netReceiver.setNetStateListener(new INetStatusListener() {
            
            @Override
            public void getNetState(int state) {
                // TODO Auto-generated method stub
                if (state == NetStatusReceiver.NETSTATUS_INAVAILABLE) {
                    Toast.makeText(getBaseContext(), "网络未连接",
                            Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(getBaseContext(), "网络已经连接",
                            Toast.LENGTH_SHORT).show();
                }
            }
        });
    }

3.为了要获取网络的状态，需要在manifest文件中设置相关权限，即配置：

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