动态监听网络状态

package com.pb.app;

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.util.Log;
import android.widget.RelativeLayout;
import android.widget.Toast;

/**
* 相关的权限：
* <uses-permission android:name="android.permission.INTERNET" />
* <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
*/
public class MainActivity extends Activity {
private RelativeLayout no_net_show;

@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
no_net_show = (RelativeLayout) findViewById(R.id.no_net_show);

/**
* 网络状态改变的广播
*
*/
registerBroadcast();
}

private void registerBroadcast() {
// 注册网络状态改变的广播
IntentFilter netfilter = new IntentFilter(
ConnectivityManager.CONNECTIVITY_ACTION);
netfilter.addCategory(Intent.CATEGORY_DEFAULT);
registerReceiver(receiver, netfilter);
}

@Override
protected void onDestroy() {
unregisterReceiver(receiver);
super.onDestroy();
}

/**
* 广播接收
*/
private BroadcastReceiver receiver = new BroadcastReceiver() {

@Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(
ConnectivityManager.CONNECTIVITY_ACTION)) {
ConnectivityManager manager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
// 获得激活的网络信息
NetworkInfo networkinfo = manager.getActiveNetworkInfo();
if(networkinfo!=null){
// 当前网络是否有效
boolean netState = networkinfo.isAvailable();
Log.i("caojing", "netState:"+netState);
// 当前网络是否已连接
boolean connState = networkinfo.isConnected();
Log.i("caojing", "connState:"+connState);
// 当前网络的类型 3G WIFI
String netType = networkinfo.getTypeName();
Log.i("caojing", "netType:"+netType);

if(netState&&connState){
no_net_show.setVisibility(RelativeLayout.GONE);
Toast.makeText(MainActivity.this, "网络连接可用,连接的为："+netType, Toast.LENGTH_SHORT).show();
}
}else{
no_net_show.setVisibility(RelativeLayout.VISIBLE);
}

}
}
};

}