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Java URL Class

Java URL Class. Represents a Uniform Resource Locator scheme (protocol) hostname port path query string. Parsing. You can use a URL object as a parser : URL u = new URL(“http://www.cs.rpi.edu/”); System.out.println(“Proto:” + u.getProtocol()); System.out.println(“File:” + u.getFile());.

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Java URL Class

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  1. Java URL Class • Represents a Uniform Resource Locator • scheme (protocol) • hostname • port • path • query string Netprog: Java URL Class

  2. Parsing • You can use a URL object as a parser: URL u = new URL(“http://www.cs.rpi.edu/”); System.out.println(“Proto:” + u.getProtocol()); System.out.println(“File:” + u.getFile()); Netprog: Java URL Class

  3. URL construction • You can also build a URL by setting each part individually: URL u = new URL(“http”, www.cs.rpi.edu,80,”/~hollingd/”); System.out.println(“URL:” + u.toExternalForm()); System.out.println(“URL: “ + u); Netprog: Java URL Class

  4. But wait, there’s more! • URL objects can retrieve the documents they refer to! • actually this depends on the protocol part of the URL. • HTTP is supported • File is supported (“file://c:\foo.html”) • You can get “Protocol Handlers” for other protocols. Netprog: Java URL Class

  5. Retrieving URL contents • There are a number of ways to do this: Object getContent(); InputStream openStream(); URLConnection openConnection(); Netprog: Java URL Class

  6. Getting Header Information • There are methods that return information extracted from response headers: String getContentType(); String getContentLength(); long getLastModified(); Netprog: Java URL Class

  7. URL Sample Code • GetPage.java: retrieves the page specified by a URL on the command line and prints it out. • GetHeaders.java: prints out some response headers given a URL. Netprog: Java URL Class

  8. URLConnection • Represents the connection (not the URL itself). • More control than URL • can write to the connection (send POST data). • can set request headers. • Closely tied to HTTP Netprog: Java URL Class

  9. URLConnection Sample • SubmitForm.java • Does an HTTP POST • URL and form field names/values specified on the command line. Netprog: Java URL Class

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