Name: boT120536 Date: 01/03/2001


Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.0-C)
Java HotSpot(TM) Client VM (build 1.3.0-C, mixed mode)

URL.openConnection() typically returns an unconnected URLConnection, on which
one can set request properties, if-modified-since (which FileURLConnection
should support also but does not), or other pre-connection properties. This is
useful, because it preserves the transparency of the URLConnection, allowing
one to set up the URLConnection is a generic way before connecting.

However, sun.net.www.protocol.file.Handler violates this by calling connect on
the URLConnection in the case of a UNC Path (a fix to 4180841). This means
that code now has to be changed to special case FileURLConnection, as there is
no way to check if a URLConnection is already connected.

Below is a program that demonstrates this. It should configure the
URLConnection prior to connecting and never actually connect to the specified
location, but if the URL includes a UNC pathname, it will throw an
IllegalAccessException at the line that says "conn.setRequestProperty(...)",
because line 72 of sun.net.www.protocol.file.Handler.java connects to the remote
resource.

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

public class URLFilePrinter
{
    public static void main( String[] args )
    {
        // Assume first argument is a URL
        try
        {
            URL location = new URL( args[0] );

            // This line should just create the URLConnection object,
            // but if it is a UNC path name, then the connection object
            // will have become connected due to line 72 of
            // sun.net.www.protocol.file.Handler.java
            URLConnection conn = location.openConnection();

            // The following line should operate fine, but if it is
            // a UNC pathname, it will throw an IllegalAccessException
            conn.setRequestProperty( "User-Agent", "MyUserAgent" );
        }
        catch( Exception ex )
        {
            System.out.println( "Exiting with exception: " + ex );
        }
    }
}
(Review ID: 114397)
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