Android上的Http连接超时不起作用

Question

我正在编写一个连接到网络服务的应用程序，如果它无法获得连接，我不希望它等待太久。因此，我设置了 httpparams 的 connectionTimeout。但这似乎没有任何作用。

为了测试，我暂时关闭了 WLAN。应用程序尝试连接很长一段时间（超过我想要的 3 秒），然后抛出 UnknownHostException。

这是我的代码：

try{
    HttpClient httpclient = new DefaultHttpClient();
    HttpParams params = httpclient.getParams();
    HttpConnectionParams.setConnectionTimeout(params, 3000);
    HttpConnectionParams.setSoTimeout(params, 3000);

    httppost = new HttpPost(URL);
    StringEntity se = new StringEntity(envelope,HTTP.UTF_8);
    httppost.setEntity(se);
    //Code stops here until UnknownHostException is thrown.
    BasicHttpResponse httpResponse = (BasicHttpResponse) httpclient.execute(httppost);

    HttpEntity entity = httpResponse.getEntity();
    return entity;

}catch (Exception e){
    e.printStackTrace();
}

有人知道我错过了什么吗？

Answer 1

尝试这样做：

HttpPost httpPost = new HttpPost(url);
StringEntity se = new StringEntity(envelope,HTTP.UTF_8);
httpPost.setEntity(se);

HttpParams httpParameters = new BasicHttpParams();
// Set the timeout in milliseconds until a connection is established.
int timeoutConnection = 3000;
HttpConnectionParams.setConnectionTimeout(httpParameters, timeoutConnection);
// Set the default socket timeout (SO_TIMEOUT) 
// in milliseconds which is the timeout for waiting for data.
int timeoutSocket = 3000;
HttpConnectionParams.setSoTimeout(httpParameters, timeoutSocket);

DefaultHttpClient httpClient = new DefaultHttpClient(httpParameters);
BasicHttpResponse httpResponse = (BasicHttpResponse)  httpClient.execute(httpPost);

HttpEntity entity = httpResponse.getEntity();
return entity;

然后你可以捕捉到一个可能的ConnectTimeoutException。

Answer 2

使用标记的解决方案，我在 30 多秒后仍然收到 UnknownHostException。在这种情况下，设备已连接到 wifi 路由器，但无法访问互联网。

所采取的方法是启动一个 AsyncTask，它只会尝试解析主机名。阻塞调用每250毫秒检查一次是否成功，4秒后取消任务并返回。

这就是我为解决它所做的：

private boolean dnsOkay = false;
private static final int DNS_SLEEP_WAIT = 250;
private synchronized boolean resolveDns(){

    RemoteDnsCheck check = new RemoteDnsCheck();
    check.execute();
    try {
        int timeSlept = 0;
        while(!dnsOkay && timeSlept<4000){
            //Log.d("RemoteDnsCheck", "sleeping");
            Thread.sleep(DNS_SLEEP_WAIT);
            timeSlept+=DNS_SLEEP_WAIT;
            //Log.d("RemoteDnsCheck", "slept");
        }
    } catch (InterruptedException e) {

    }

    if(!dnsOkay){
        Log.d("resolveDns", "cancelling");
        check.cancel(true);
        Log.d("resolveDns", "cancelled");
    }
    return dnsOkay;
}

private class RemoteDnsCheck extends AsyncTask<Void, Void, Void>{

    @Override
    protected Void doInBackground(Void... params) {
        try {
            Log.d("RemoteDnsCheck", "starting");
            dnsOkay = false;
            InetAddress addr = InetAddress.getByName(baseServiceURL);
            if(addr!=null){
                Log.d("RemoteDnsCheck", "got addr");
                dnsOkay = true;
            }
        } catch (UnknownHostException e) {
            Log.d("RemoteDnsCheck", "UnknownHostException");
        }
        return null;
    }

}

然后，每当我想进行网络调用时，都会在函数的开头调用它：

    if(!resolveDns()){
        return null;
    }

Answer 3

见：https://stackoverflow.com/a/20031077/2609238

问题可能出在 Apache HTTP 客户端中。请参阅 HTTPCLIENT-1098。已在 4.1.2 中修复。

超时异常尝试反向 DNS IP，以进行日志记录。这需要额外的时间才能真正触发异常。

Answer 4

这个方法对我有用：

AndroidHttpTransport androidHttpTransport = new AndroidHttpTransport( endpoint, 3000) ;

Answer 5

HttpConnectionParams.setConnectionTimeout(httpParameters, timeoutConnection);
// Set the default socket timeout (SO_TIMEOUT)