6.3. A Front End to Various Search Engines

Listing 6.1 presents an example that makes use of the two most common status codes other than 200 (OK): 302 (Found) and 404 (Not Found). The 302 code is set by the shorthand sendRedirect method of HttpServletResponse, and 404 is specified by sendError.

In this application, an HTML form (see Figure 6-1 and the source code in Listing 6.3) first displays a page that lets the user choose a search string, the number of results to show per page, and the search engine to use. When the form is submitted, the servlet extracts those three parameters, constructs a URL with the parameters embedded in a way appropriate to the search engine selected (see the SearchSpec class of Listing 6.2), and redirects the user ...

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