Java URL java.net.ConnectException 错误(Ping 有效，其他 URL 有效)

Question

我正在编写一个程序，它从列表中读取一些 ID，从中找出不同的 URL，然后将图像保存到我的 C: 驱动器中。

如果我在浏览器中导航到图像 URL，它们就会起作用。此外，如果我尝试从不同的服务器获取图像的 URL，则该程序完全可以工作。问题是当我尝试连接到此 URL 上的特定图像时，它似乎不起作用。奇怪的是，当我 ping URL 时，丢包率为 0%。此外，我的浏览器没有使用特殊的代理设置，这会导致它通过 Java 程序运行。

以下错误/输出的原因可能是什么？

Job started ...
1) AC_0A47_EXT1.jpg 2/0/47/307/398/HA47H01_H.jpg
Exception #3 java.net.ConnectException: Connection timed out: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at sun.net.NetworkClient.doConnect(Unknown Source)
at sun.net.www.http.HttpClient.openServer(Unknown Source)
at sun.net.www.http.HttpClient.openServer(Unknown Source)
at sun.net.www.http.HttpClient.<init>(Unknown Source)
at sun.net.www.http.HttpClient.New(Unknown Source)
at sun.net.www.http.HttpClient.New(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.connect(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
at java.net.URL.openStream(Unknown Source)
at pullVFMImagesFromVFMURLs.writeImage(pullVFMImagesFromVFMURLs.java:99)
at pullVFMImagesFromVFMURLs.pullvfmimagesfromvfmurls(pullVFMImagesFromVFMURLs.java:48)
at pullVFMImagesFromVFMURLs.main(pullVFMImagesFromVFMURLs.java:21)

更多信息:

ID列表(MissingImagez.txt)如下:

AC_0A47_EXT1.jpg|2/0/47/307/398/xxx.jpg
AC_0C09_EXT1.jpg|3/0/44/130/589/xyz.jpg
AC_0C16_RM1.jpg|3/0/44/602/895/zzz.jpg
AC_0C17_BAR1.jpg|3/0/45/284/10/www.jpg

对应的代码如下:

  public static void main(String[] args)
  {
    pullImagesFromURLs processor = new pullImagesFromURLs();

    String passParam = null;

    for (int i = 0; i < args.length; i++)
       passParam = (args[i].toString().toUpperCase());

    processor.pullvfmimagesfromvfmurls(passParam);
  }

  public void pullvfmimagesfromvfmurls(String passParam)
  {
    System.out.println("Job started ...");

    try
    {     
       boolean bOK = false;
       String sOrigName = "";
       String sURL = ""; 
       int iCount = 0;
       int iInt = 0;

       try
       {
          BufferedReader in = new BufferedReader(new FileReader("/tmp/missingImagez.txt"));
          String str;

          while ((str = in.readLine()) != null)
          {       
             iInt = str.indexOf("|");     
             sOrigName = str.substring(0,iInt);
             sURL = str.substring(iInt+1);
             iCount ++;
             System.out.println(iCount + ") " + sOrigName + " " + sURL);
             bOK = writeImage(sOrigName, sURL);         
          }           

          try
          {
             if (in != null)
                in.close();             
          }      
          catch (Exception e)
          {
          }

       }
       catch (IOException e)
       {
         System.out.println("Exception #1 " + e);
       }
    }

    catch (Exception e)
    {
       System.out.println("Exception #2 " + e);
       System.exit(-666);
    }

    System.out.println("Job completed");

    System.exit(-666);

  } 
 private static boolean writeImage(String origName, String vfmURL) 
  {

    boolean bOK = true;
    String sPath = "C:/images/img2754/";

    try
    {
       final String vfmURLPrefix = new String("http://www.blah.blah2.com/imageRepo/");

       BufferedInputStream stream = null; 
       FileOutputStream destination = null;
       URLConnection urlc = null;
       int readSize = 1024 * 50;
       int bytes_read;
       URL url = null;

        url = new URL(vfmURLPrefix + vfmURL);
        urlc = url.openConnection();
        urlc.setDoOutput(true);
        stream = new BufferedInputStream(url.openStream());
        System.out.println(url.toString());
        destination = new FileOutputStream(sPath+origName);
        byte[] buffer = new byte[readSize];

        while(true)
        {       

           bytes_read = stream.read(buffer);
           if (bytes_read == -1) {break;}
             destination.write(buffer, 0, bytes_read);
             stream.close(); 
        }

        if(stream != null)
            stream.close();

        if(destination != null) 
           destination.close();

    }

    catch(Exception e)
    {
       System.out.println("Exception #3 " + e);
    }
    return bOK;

  }

尝试使用 Apache HttpComponents。得到以下输出:好吧——我试过了……现在我明白了:

Exception #3     org.apache.http.conn.HttpHostConnectException: Connection to http://www.blah.blah2.com/ refused. 
    at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:190)
        at org.apache.http.impl.conn.ManagedClientConnectionImpl.open(ManagedClientConnectionImpl.java:294)
        at org.apache.http.impl.client.DefaultRequestDirector.tryConnect(DefaultRequestDirector.java:640)
        at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:479)
        at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:906)
        at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:805)
        at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:784)
        at pullVFMImagesFromVFMURLs.writeImage(pullVFMImagesFromVFMURLs.java:100)
        at pullVFMImagesFromVFMURLs.pullvfmimagesfromvfmurls(pullVFMImagesFromVFMURLs.java:55)
        at pullVFMImagesFromVFMURLs.main(pullVFMImagesFromVFMURLs.java:28)
    Caused by: java.net.ConnectException: Connection timed out: connect
        at java.net.DualStackPlainSocketImpl.connect0(Native Method)
        at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
        at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
        at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
        at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
        at java.net.PlainSocketImpl.connect(Unknown Source)
        at java.net.SocksSocketImpl.connect(Unknown Source)
        at java.net.Socket.connect(Unknown Source)
        at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:127)
        at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:180)
        ... 9 more

Answer 1

编辑2

您的代码在读取循环中存在错误。 InputStream.read不需要返回正在接收的整个字节流。 (可能尚未全部可用。)按照您的编码方式，输入流通常会过早关闭。这会导致与您发布的错误不同的错误(“流已关闭”)。

无论如何，修复循环后，我能够运行您的代码来下载此图像，没有任何问题。

原创

顺便说一句，你的代码有点令人困惑。特别是，您的代码创建 URLConnection，但直接从 URL 打开流。 URLConnection基本没用过。这也很令人困惑，因为您调用了 setDoOutput，但没有调用 setDoInput。我会像这样重写你的代码:

url = new URL(vfmURLPrefix + vfmURL);
urlc = url.openConnection();
stream = new BufferedInputStream(urlc.getInputStream()); // connect/request will be made.

不过，我怀疑这能否解决您当前的问题。要调试您当前的问题，我建议您在浏览器中请求相同的图像 URL 时使用 Firebug 或 Chrome 的开发人员工具来嗅探网络连接/请求/响应。您可能会发现意外的重定向、状态代码、cookie 或类似内容。有了这些额外的知识，您就可以尝试将连接转换为 HttpURLConnection以便您有更多选项可用于自定义请求。