Android 网络连接--Wifi/3G

获取网络连接状态

随着3G和Wifi的推广，越来越多的Android应用程序需要调用网络资源，检测网络连接状态也就成为网络应用程序所必备的功能。

Android平台提供了ConnectivityManager 类，用于网络连接状态的检测。

Android开发文档这样描述ConnectivityManager 的作用：

Class that answers queries about the state of network connectivity. It also notifies applications when network connectivity changes. Get an instance of this class by calling

Context.getSystemService(Context.CONNECTIVITY_SERVICE).

The primary responsibilities of this class are to:

Monitor network connections (Wi-Fi, GPRS, UMTS, etc.)
Send broadcast intents when network connectivity changes
Attempt to "fail over" to another network when connectivity to a network is lost
Provide an API that allows applications to query the coarse-grained or fine-grained state of the available networks
下面这个简单的例子 checkNetworkInfo() 说明了如何编程获取Android手机的当前网络状态
[java] private void checkNetworkInfo()
   {
       ConnectivityManager conMan = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

       //mobile 3G Data Network
       State mobile = conMan.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState();
       txt3G.setText(mobile.toString()); //显示3G网络连接状态
       //wifi
       State wifi = conMan.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState();
       txtWifi.setText(wifi.toString()); //显示wifi连接状态
   }

private void checkNetworkInfo()
{
ConnectivityManager conMan = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

        //mobile 3G Data Network
        State mobile = conMan.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState();
        txt3G.setText(mobile.toString()); //显示3G网络连接状态
        //wifi
        State wifi = conMan.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState();
        txtWifi.setText(wifi.toString()); //显示wifi连接状态
    }

注:

根据Android的安全机制，在使用ConnectivityManager时，必须在AndroidManifest.xml中添加<uses-permission
android:name="android.permission.ACCESS_NETWORK_STATE" /> 否则无法获得系统的许可。

运行结果(关闭3G及wifi网络连接的状态下)

调用Android手机的网络配置界面

使用过Android手机上的手机QQ的朋友，应该知道，当QQ启动时，如果没有有效的网络连接，QQ会提示转入手机的网络配置界面。这是如何实现的呢。

[java] private void checkNetworkInfo()
    {
        ConnectivityManager conMan = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

        //mobile 3G Data Network
        State mobile = conMan.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState();
        txt3G.setText(mobile.toString());
        //wifi
        State wifi = conMan.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState();
        txtWifi.setText(wifi.toString());

        //如果3G网络和wifi网络都未连接，且不是处于正在连接状态则进入Network Setting界面由用户配置网络连接
        if(mobile==State.CONNECTED||mobile==State.CONNECTING)
            return;
        if(wifi==State.CONNECTED||wifi==State.CONNECTING)
            return;


        startActivity(new Intent(Settings.ACTION_WIRELESS_SETTINGS));//进入无线网络配置界面
        //startActivity(new Intent(Settings.ACTION_WIFI_SETTINGS)); //进入手机中的wifi网络设置界面

    }

private void checkNetworkInfo()
{
ConnectivityManager conMan = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

        //mobile 3G Data Network
        State mobile = conMan.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState();
        txt3G.setText(mobile.toString());
        //wifi
        State wifi = conMan.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState();
        txtWifi.setText(wifi.toString());

        //如果3G网络和wifi网络都未连接，且不是处于正在连接状态则进入Network Setting界面由用户配置网络连接
        if(mobile==State.CONNECTED||mobile==State.CONNECTING)
            return;
        if(wifi==State.CONNECTED||wifi==State.CONNECTING)
            return;


        startActivity(new Intent(Settings.ACTION_WIRELESS_SETTINGS));//进入无线网络配置界面
        //startActivity(new Intent(Settings.ACTION_WIFI_SETTINGS)); //进入手机中的wifi网络设置界面

    }
运行结果(关闭3G及wifi网络连接的状态下)，程序转入无线网络配置界面

[java] <SPAN style="FONT-SIZE: 18px"><STRONG>startActivity(new Intent(Settings.ACTION_WIRELESS_SETTINGS));//进入无线网络配置界面</STRONG></SPAN>

startActivity(new Intent(Settings.ACTION_WIRELESS_SETTINGS));//进入无线网络配置界面

如果调用

[ja

补充：移动开发 , Android ,