Android 检測网络是否连接

权限：

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

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

代码例如以下：

package com.example.nettest;



import android.net.ConnectivityManager;

import android.net.NetworkInfo.State;

import android.os.Bundle;

import android.app.Activity;

import android.app.AlertDialog;

import android.content.ComponentName;

import android.content.Context;

import android.content.DialogInterface;

import android.content.Intent;

import android.view.Menu;

import android.widget.TextView;

import android.widget.Toast;





public class MainActivity extends Activity {





private ConnectivityManager manager;

private TextView tv;

StringBuffer sb = new StringBuffer(256);





@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);





tv = (TextView) findViewById(R.id.textView1);

checkNetworkState();

}





/**

* 检測网络是否连接

* 

* @return

*/

private boolean checkNetworkState() {

boolean flag = false;

// 得到网络连接信息

manager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

// 去进行推断网络是否连接

if (manager.getActiveNetworkInfo() != null) {

flag = manager.getActiveNetworkInfo().isAvailable();

}

if (!flag) {

setNetwork();

} else {

isNetworkAvailable();

}

tv.setText(sb.toString());

return flag;

}





/**

* 网络未连接时。调用设置方法

*/

private void setNetwork() {

Toast.makeText(this, "wifi is closed!", Toast.LENGTH_SHORT).show();

AlertDialog.Builder builder = new AlertDialog.Builder(this);

builder.setIcon(R.drawable.ic_launcher);

builder.setTitle("网络提示信息");

builder.setMessage("网络不可用。假设继续，请先设置网络！

");

builder.setPositiveButton("设置", new DialogInterface.OnClickListener() {

@Override

public void onClick(DialogInterface dialog, int which) {

Intent intent = null;

/**

* 推断手机系统的版本号！

假设API大于10 就是3.0+ 由于3.0以上的版本号的设置和3.0下面的设置不一样。调用的方法不同

*/

if (android.os.Build.VERSION.SDK_INT > 10) {

intent = new Intent(

android.provider.Settings.ACTION_SETTINGS);

} else {

intent = new Intent();

ComponentName component = new ComponentName(

"com.android.settings",

"com.android.settings.WirelessSettings");

intent.setComponent(component);

intent.setAction("android.intent.action.VIEW");

}

startActivity(intent);

}

});





builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {

@Override

public void onClick(DialogInterface dialog, int which) {

}

});

builder.create();

builder.show();

}





/**

* 网络已经连接，然后去推断是wifi连接还是GPRS连接 设置一些自己的逻辑调用

*/

private void isNetworkAvailable() {





State gprs = manager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE)

.getState();

State wifi = manager.getNetworkInfo(ConnectivityManager.TYPE_WIFI)

.getState();

if (gprs == State.CONNECTED || gprs == State.CONNECTING) {

Toast.makeText(this, "gprs is open! ", Toast.LENGTH_SHORT).show();

sb.append("\ngprs is open! ");

} else {

sb.append("\ngprs is closed! ");

}





// 推断为wifi状态下才载入广告，假设是GPRS手机网络则不载入。

if (wifi == State.CONNECTED || wifi == State.CONNECTING) {

Toast.makeText(this, "wifi is open! ", Toast.LENGTH_SHORT).show();

loadAdmob();

sb.append("\nwifi is open! ");

} else {

sb.append("\nwifi is closed! ");

}





}





/**

* 在wifi状态下 载入admob广告

*/

private void loadAdmob() {

Toast.makeText(getApplicationContext(), "ad is loding..", 1).show();

sb.append("\nad is loding...");

}

}