Request Handling Methods | Java Servlets tuto

Request Handling Methods

The basic Servlet interface defines a service method for handling client requests.
This method is called for each request that the servlet container routes to an instance of a servlet.
The handling of concurrent requests to a Web application generally requires that the Web Developer design servlets that can deal with multiple threads executing within the service method at a particular time.
Generally the Web container handles concurrent requests to the same servlet by concurrent execution of the service method on different threads.

HTTP Specific Request Handling Methods

The HttpServlet abstract subclass adds additional methods beyond the basic Servlet interface that are automatically called by the service method in the HttpServlet class to aid in processing HTTP-based requests.
These methods are:
=> doGet for handling HTTP GET requests
=> doPost for handling HTTP POST requests
=> doPut for handling HTTP PUT requests
=> doDelete for handling HTTP DELETE requests
=> doHead for handling HTTP HEAD requests
=> doOptions for handling HTTP OPTIONS requests
=> doTrace for handling HTTP TRACE requests
Typically when developing HTTP-based servlets, a Servlet Developer will only concern himself with the doGet and doPost methods. The other methods are considered to be methods for use by programmers very familiar with HTTP programming.

 Additional Methods

The doPut and doDelete methods allow Servlet Developers to support HTTP/1.1 clients that employ these features. The doHead method in HttpServlet is a specialized form of the doGet method that returns only the headers produced by the doGet method. The doOptions method responds with which HTTP methods are supported by the servlet. The doTrace method generates a response containing all instances of the headers sent in the TRACE request.

Conditional GET Support

The HttpServlet interface defines the getLastModified method to support conditional GET operations. A conditional GET operation requests a resource be sent only if it has been modified since a specified time. In appropriate situations, implementation of this method may aid efficient utilization of network resources.