Android检测网络状况

功能：当网络不可用时Toast提示。

使用步骤：

1、注册权限

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

2、编写NetworkStatusReceiver 类继承 BroadcastReceiver 复写 onReceive方法

package receiver;

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

/**
* 检测网络状况广播接收者
* @author chenql
*/
public class NetworkStatusReceiver extends BroadcastReceiver {

private ConnectivityManager connectivityManager;
private NetworkInfo networkInfo;

@Override
public void onReceive(Context context, Intent intent) {

connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
networkInfo = connectivityManager.getActiveNetworkInfo();

if (networkInfo == null || !(networkInfo.isAvailable())) {
// 网络不可用时提示
Toast.makeText(context, "network is unavailable", Toast.LENGTH_SHORT).show();
}
}
}

3、在基类的 onCreate()方法中注册（这样所有继承基类的activity都会监听，也可以根据实际需要，包装到基类的一个方法中，由子类决定是否调用以监听网络状况。）

IntentFilter intentFilter = new IntentFilter();
// 添加监听网络状况的action
intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
NetworkStatusReceiver networkStatusReceiver = new NetworkStatusReceiver();
registerReceiver(networkStatusReceiver, intentFilter);

4、在基类的onDestroy()方法中取消注册（如果依照上述操作在子类中调用注册广播的方法，则在基类的onDestroy()方法中取消注册前还应当判断对应的广播接收者networkStatusReceiver是否为空。）

@Override
protected void onDestroy() {
super.onDestroy();

if (networkStatusReceiver != null) {
unregisterReceiver(networkStatusReceiver);
}
}