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The Book
Chapter 6 Examples from Java Servlet Programming, 2nd Ed

  • 6-1: A WML minibartender, drinks.wml
  • 6-4 and 6-5: Using WML to ask for an area code
  • 6-6: Hello World graphics
  • 6-7: A chart comparing applets and oranges
  • 6-8: Drawing over an image to mark it confidential
  • 6-9: Combining images to form a graphical counter
  • 6-10: An image effect converting an image to grayscale
  • 6-12: Sending compressed content
  • 6-13: Countdown to a rocket launch

Examples from other chapters:

Example 6.1: A WML minibartender, drinks.wml
This example is not a servlet. It's a static WML document that acts as a minibartender with dynamic qualities built into the WML. The example provides a list of drinks to choose from, then displays the ingredients of the selected drink. Notice the document is XML with a well-known DTD.
    • Try it (Requires a phone simulator, see the book)
    • Source (WML with an XML extension)
    • Source (web.xml)

Example 6.4 and 6.5: Using WML to ask for an area code
This WML file and servlet demonstrate anarea code lookup application. A client may enter a telephone area code into the form, submit it to the servlet, and learn which state or region contains that code. People with WAP-enabled phones can use this application to physically locate any Caller ID number.
    • Try it (Requires a phone simulator, see the book)
    • Source (WML with an XML extension)
    • Source (Supporting servlet)

Example 6.6: Hello World graphics
This servlet generates and returns a GIF image. The graphic says "Hello World!"

Example 6.7: A chart comparing applets and oranges
This servlet creates a bar chart that compares apples to oranges, with regard to their annual consumption. There's little need for this chart to be dynamically generated, but it lets us get the point across without too much code. Picture in your mind's eye that the servlet is charting up-to-the-minute stock values or the server's recent load.

Example 6.8: Drawing over an image to mark it confidential
This servlet writes "CONFIDENTIAL" over every image it returns. The image name is passed to the servlet as extra path information.

Example 6.9: Combining images to form a graphical counter
This servlet displays a hit count as a sequence of individual number images combined into one large image.

Example 6.10: An image effect converting an image to grayscale
This servlet shows a servlet that converts an image to grayscale before returning it. The servlet performs this effect without ever actually creating an off-screen graphics context. Instead, it creates the image using a special ImageFilter.

Example 6.12: Sending compressed content
This servlet is the ViewResource servlet from Chapter 4 rewritten to send compressed content whenever possible. An end user cannot tell that the server sent compressed content to the browser--except perhaps with reduced download times. It's disabled because the servlet would happily serve any files from this site.
    • Try it (disabled for security)
    • Source

Example 6.13: Countdown to a rocket launch
This servlet uses server push to display a countdown to a rocket launch. It begins by sending a series of pages that count down from 10 to 1. Every page replaces the previous page. When the countdown reaches 0, the servlet sends a picture of a launch. It uses the com.oreilly.servlet.MultipartResponse utility class to manage the server push details. This example does not work with Microsoft Internet Explorer nor with Netscape Navigator 6. IE doesn't support server push and NN6 has severe bugs in this area. Mozilla/Firefox is your best bet.

 


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