Displaying a URL from a Java application

Question

Hi,
I recently implemented a test Java application based on Steven Spencer's Java Tip 66: "Control browsers from your Java application" (http://www.javaworld.com/javaworld/javatips/jw-javatip66.html). Spencer's example tests for the current operating system, sets some constants based on the OS that it finds, and then calls the Runtime.getRuntime( ).exec( ) method. During the call, you can pass either a file:// or http:// URL. I can get the example to work perfectly given a file:// URL but have limited success supplying the http:// URL. When I supply a specific http:// URL such as "http://someserver/somedir/testfile.htm" the browser returns a "Cannot open URL" error. However, if I supply a URL that does not resolve to a specific HTML file, such as "http://someserver/somedir", and the directory has either a "index.htm" or "index.html" file, the application works fine. I would like to be able to pass an http:// URL that resolves to a specific HTML file. I am trying to implement context-sensitive help from within a Java application. I am testing this on a machine running Windows 2000 and using Microsoft's IE 5.x browser. Any help would be appreciated.
Thanks,
Scott Rifenbark

Answer 1

The browser doesn't know that it was started by this Java code, you know. So you are asking why your browser (Internet Explorer) doesn't let you get at specific files. The answer is, that isn't how the Internet works. A URL is a "Uniform Resource Locator" (or something a lot like that). It locates a resource on the Internet. This resource may or may not be a file, but as the client you have no way of knowing whether what you get in response to that is a file on the server or whether it has been generated by some CGI program there.
When you send an http:// URL to a web server, it looks at what you have sent and goes through its configuration files. Using this it translates that URL into either a file on the server (which it returns to you) or a program which it calls to return data to you. If it was a file, its local name on the server doesn't have to be related in any way to the contents of the URL.
It sounds like you are planning to be the one setting up those files on the server, though. If that's the case, you have to configure the server appropriately for your needs.