Chapter 17: Using Applets As Servlet Front Ends

Source Code in This Chapter

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• A Multisystem Search Engine Front End
  • SearchApplet.java An applet that reads a value from a TextField, then uses it to build three distinct URLs with embedded GET data: one each for Google, Infoseek, and Lycos. The browser is directed to retrieve each of these URLs, displaying them in side-by-side frame cells. Uses the SearchSpec class to represent information about the search engines.
  • ParallelSearches.html Page that defines the frame structure for parallel searches page.
  • SearchAppletFrame.html Top frame cell of parallel searches page. Contains the search applet.
  • GoogleResultsFrame.html Initial empty cell to contain results from Google. (Remember that you must provide initial content for all frame cells to be used with Netscape.)
  • InfoseekResultsFrame.html Initial empty cell to contain results from Infoseek. (Remember that you must provide initial content for all frame cells to be used with Netscape.)
  • LycosResultsFrame.html Initial empty cell to contain results from Lycos. (Remember that you must provide initial content for all frame cells to be used with Netscape.)
• A Search Engine Query Viewer That Uses Object Serialization and HTTP Tunneling
  • ShowQueries.java Applet that reads arrays of strings packaged inside a QueryCollection and places them in a scrolling TextArea. The QueryCollection obtains the strings by means of a serialized object input stream connected to the QueryGenerator.java servlet.
  • QueryCollection.java A class to load sample search engine queries from the server in a background process. When this class is built, it returns a value immediately, but this value returns false for isDone and null for getQueries. Meanwhile, it starts a Thread to request an array of query strings from the server, reading them in one fell swoop by means of an ObjectInputStream. Once they’ve all arrived, they are placed in the location getQueries returns, and the isDone flag is switched to true. Used by the ShowQueries applet.
  • ShowQueries.html The HTML page containing the ShowQueries applet.
  • QueryGenerator.java Servlet that generates an array of strings and sends them via an ObjectOutputStream to applet or other Java client.
• An Applet That Sends POST Data
  • SendPost.java Applet that reads firstName, lastName, and emailAddress parameters and sends them via POST to the host, port, and URI specified. Uses the LabeledTextField class. The first example in the book submits the result to the ShowParameters servlet from Chapter 3.
  • SendPost.html The HTML page containing the SendPost applet.

URLs in This Chapter

• Google
• Infoseek
• Lycos

General

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