使用 ICS 更改 wifi 网络时，ErrnoException：isConnected 失败：EHOSTUNREACH（没有到主机的路由）

在 ics 上使用我的应用程序时，将 wifi 网络从网络更改为网络后，所有图像请求都开始返回，但出现异常。

异常失败

> org.apache.http.conn.HttpHostConnectException: Connection to
> https://m1.testapp.com refused    at
> org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:183)
>   at
> org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
>   at
> org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
>   at
> org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
>   at
> org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
>   at
> org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
>   at
> org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
>   at
> com.testApp.android.ws.PooledRequestProcessor$Runner.run(PooledRequestProcessor.java:298)
>   at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
>   at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
>   at java.lang.Thread.run(Thread.java:856)  Caused by:
> java.net.ConnectException: failed to connect to /109.233.153.38 (port
> 443) after 20000ms: isConnected failed: EHOSTUNREACH (No route to
> host)     at
> org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:181)
>   ... 10 more  Caused by: java.net.SocketException: failed to connect
> to /109.233.153.38 (port 443) after 20000ms: isConnected failed:
> EHOSTUNREACH (No route to host)   at
> libcore.io.IoBridge.isConnected(IoBridge.java:220)    at
> libcore.io.IoBridge.connectErrno(IoBridge.java:152)   at
> libcore.io.IoBridge.connect(IoBridge.java:112)    at
> java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)    at
> java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459)    at
> java.net.Socket.connect(Socket.java:842)      at
> org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:119)
>   at
> org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:144)
>   ... 10 more  Caused by: libcore.io.ErrnoException: isConnected
> failed: EHOSTUNREACH (No route to host)   at
> libcore.io.IoBridge.isConnected(IoBridge.java:201)

最奇怪的是，即使卸载应用程序并重新安装也无法解决问题，只需关闭然后打开手机即可。

我在这里看到了类似的问题http://groups.google.com/group/newsrob/browse_thread/thread/ea2f26d9d1753b79/5800e268eeab399c#5800e268eeab399c http://groups.google.com/group/newsrob/browse_thread/thread/ea2f26d9d1753b79/5800e268eeab399c#5800e268eeab399c。这个问题不会出现在 4.0.3 的手机上，只会出现在 4.0.1 的手机上，而且欧洲似乎还没有提供更新。

也许由于某种原因需要一段时间才能进行切换？您可以在发出请求之前检查是否存在活动的网络连接：

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

if (networkInfo != null && networkInfo.isConnected() && networkInfo.isAvailable())
{
    // DO WHAT YOU NEED TO DO ON THE NETWORK
}
else
{
    // PROMPT USER THAT NETWORK IS DISCONNECTED

        Toast.makeText(this, "There is no active network connection!", 5000).show();
}