如果服務器沒有響應，則超時不起作用

Question

我有問題，當服務器沒有響應時，我從來沒有得到SocketTimeOutException。 30秒後，我得到一個IOException。

當服務器沒有響應時，我需要做些什麼來獲得超時？

這是我的代碼，其中第一個URL工作，第二個結果在IOException而不是SocketTimeOutException。

公共類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); 
    } 
} 

}

我也試圖與阿帕奇HttpClient的，但同樣的事情出現。

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

你試圖打開通過testUrl.openConnection()連接，其中testUrl是URL類型。那麼，如果你看看具體javadoc，你會注意到URL.openConnection()永遠不會拋出SocketTimeoutException。它只能拋出一個IOException。

Answer 2

可以趕上IOException異常，並在catch塊

Answer 3

1. 連接對象是通過調用一個URL的openConnection方法創建拋出一個新的SocketTimeOutException。
2. 操作設置參數和一般請求屬性。
3. 使用連接方法建立到遠程對象的實際連接。
4. 遠程對象變爲可用。可以訪問標題字段和遠程對象的內容。