如果服务器没有响应，超时不起作用

Question

我有一个问题，当服务器没有响应时，我永远不会收到 SocketTimeOutException 。 30 秒后，我收到了 IOException。

当服务器没有响应时，我需要做什么才能超时？

这是我的代码，其中第一个 URL 起作用，第二个 URL 产生 IOException 而不是 SocketTimeOutException。

public class TestConnection {

public static final int TIMEOUT_VALUE = 5000;

public static void main(String[] arg){

    try {
        URL testUrl = new URL("http://www.doublegames.com/images/games140/scrabble-cubes-online_140x140.jpg");
        testTimeOut(testUrl);
        testUrl = new URL("http://tamblang.co.cc/wp-content/uploads/2010/08/cd7ce2_command-038-conquer-4-tiberian-twilight-140x140.jpg");
        testTimeOut(testUrl);

    } catch (MalformedURLException e) {
        e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
    }
}
private static void testTimeOut(URL testUrl) {
    try {
        long start = System.nanoTime();
        HttpURLConnection testConnection = (HttpURLConnection) testUrl.openConnection();
        testConnection.setConnectTimeout(TIMEOUT_VALUE);
        testConnection.setReadTimeout(TIMEOUT_VALUE);


        BufferedReader in = new BufferedReader(new InputStreamReader(testConnection.getInputStream()));
        long elapsed = System.nanoTime() - start;
        System.out.println("Elapsed (ms): " + elapsed / 1000000);
        System.out.println("Connection worked for " + testUrl);
    } catch (SocketTimeoutException e) {
        System.out.println("More than " + TIMEOUT_VALUE + " elapsed." + testUrl);
    } catch(IOException ioe){
        System.out.println("No timeout for " + testUrl);
    }
}

}

我也尝试过 apaches HttpClient 但同样的事情。

private static void testTimeOut(URL testUrl) {
    long start = 0;
    try {
        start = System.nanoTime();

        HttpParams httpParams = new BasicHttpParams();
        HttpConnectionParams.setConnectionTimeout(httpParams, TIMEOUT_VALUE);
        HttpConnectionParams.setSoTimeout(httpParams, TIMEOUT_VALUE);
        HttpClient httpClient = new DefaultHttpClient(httpParams);

        HttpGet httpget = new HttpGet(testUrl.toString());
        HttpResponse response = httpClient.execute(httpget);


        // Get hold of the response entity
        HttpEntity entity = response.getEntity();

        // If the response does not enclose an entity, there is no need
        // to bother about connection release
        if (entity != null) {
            InputStream instream = entity.getContent();
                BufferedReader in = new BufferedReader(new InputStreamReader(instream));
                // do something useful with the response
                 long elapsed = System.nanoTime() - start;
                System.out.println("Elapsed (ms): " + elapsed / 1000000);
                System.out.println("Connection worked for " + testUrl);

            }
    }catch(Exception e){
        long elapsed = System.nanoTime() - start;
        System.out.println("Elapsed (ms): " + elapsed / 1000000);
        System.out.println("No timeout for " + testUrl + " after " + elapsed / 100000);
    }
}

Answer 1

您正在尝试通过 testUrl.openConnection() 打开连接，其中 testUrl 的类型为 URL。好吧，如果您查看特定的 javadoc，您会注意到 URL.openConnection() 永远不会抛出 SocketTimeoutException。它只能抛出IOException。

Answer 2

您可以捕获 IOException 并在 catch 块中抛出一个新的 SocketTimeOutException

Answer 3

1. 连接对象是通过调用 URL 上的 openConnection 方法创建的。
2. 操纵设置参数和一般请求属性。
3. 使用 connect 方法建立与远程对象的实际连接。
4. 远程对象变得可用。可以访问远程对象的标头字段和内容。