Name: diC59631 Date: 06/10/98


After closing a http connection to a URL that has KeepAlive set, any attempt to try to connect the same URL or URLs in the same domain results in a NullPointer exception thrown at HttpURLConnection.getHeaderField. I even tried to stop the KeepAlive timer thread before reopen the connection.



---------stack dump------------------------------
java.lang.NullPointerException
        at sun.net.ProgressData.unregister(ProgressData.java:99)
        at sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:495)
        at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:416)
        at sun.net.www.protocol.http.HttpURLConnection.getHeaderField(HttpURLConnection.java:696)
        at UrlBug.main(UrlBug.java:52)

---------source code-----------------------------

import java.net.*;
import java.io.*;

class UrlBug {

  public static void main(String argv[]) {
    try {
      // get page where server sets Connection: keep-alive
      URL url = new URL("http://www.levi.com/us/");
      HttpURLConnection http = (HttpURLConnection) url.openConnection();
      http.connect();
      System.err.println("If you see keep-alive here: " +
http.getHeaderField("Connection"));

      BufferedReader r =
new BufferedReader(new InputStreamReader(http.getInputStream()));
      String line;
      
      while ((line = r.readLine()) != null) {
System.out.println(line);
      }
      r.close();
      http.disconnect();
      
      // tried to kill the KeepAlive timer thread
      ThreadGroup top_group = Thread.currentThread().getThreadGroup();

      Thread[] threads=new Thread[top_group.activeCount()];
      int num_threads = top_group.enumerate(threads);
      
      for(int j=0;j<num_threads;j++) {
System.err.println(" The "+j+"th thread is "+threads[j].toString());
if(threads[j] != Thread.currentThread()) {
threads[j].stop();
}
      }
     

      // now get page from same server
      url = new URL("http://www.levi.com/us/top.aspff");
      http = (HttpURLConnection) url.openConnection();
      http.connect();
      System.err.println("And you don't see it here: " +
http.getHeaderField("Connection")); // this is where the null pointer exception thrown
      // r = new BufferedReader(new InputStreamReader(http.getInputStream()));
      //while ((line = r.readLine()) != null) {
//System.out.println(line);
      // }
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}
(Review ID: 32633)
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