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4: Developing applications >
4.2: Building Web applications >
4.2.4: Accessing data >
4.2.4.4: Providing ways for clients to invoke applications >
4.2.4.4.1: Providing Web clients access to JSP files >
4.2.4.4.1.2: Invoking servlets and JSP files within HTML forms >
4.2.4.4.1.2.1: Example: Invoking servlets within HTML forms

4.2.4.4.1.2.1: Example: Invoking servlets within HTML forms

Suppose the application programmer uses an HTML form to provide users access to a servlet. Assuming the METHOD attribute on the FORM tag is "GET," the flow is as follows:

  1. The user views the form in a browser. The user provides information requested by the form and specifies to submit the form (usually by clicking a Submit button or other button visible on the form).
  2. The form encodes the user-supplied information into a URL-encoded query string. It appends the query string to the servlet URL and submits the entire URL.
  3. The servlet processes the information. The getParameterNames(), getParameter(), and getParameterValues() methods of the HttpServletRequest object provide access to the form parameter names and values in the client request. The extraction process also decodes the names and values.
  4. Often, the final action of the servlet is to dynamically create an HTML response (based on parameter input from the form) and pass it back to the user through the server. Methods of the HttpServletResponse object are used to send the response, which is sent back to the client as a complete HTML page.

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Go to previous article: Invoking servlets and JSP files within HTML forms Go to next article: Providing Web clients access to servlets