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Explain the underlying method of Servlet interface.1. init()
2. service()
3. destroy()
4. getServletConfig()
5. getServletInfo()
1. init() :
- This method initializes the servlet.
- It invokes only once and automatically invoked by the servlet engine / container.
- This method is used and guarantees the actions that are to be performed before the service() method is invoked.
- This is an overloaded method with no parameter and one ServletConfig object.
- Incase of a fatal error during initialization, the init() method throws UnavailableException object.
2. service() :
- To carry a single request sent by a client, this method is used.
- This method implements / performs the paradigm of request and response.
- The request object contains the information of the service request including the client sent parameters.
- The response object is used to send the response to the client.
- The quality of handling these two methods rely on the underlying network environment.
3. destroy() :
- Invoked just before the stopping the operations by the servlet.
- It performs the resources cleaning process such memory, files, threads removal and ensures the persistence state is synchronized by the servlet’s current in-memory state.
- The destroy() method invoked only once before the unloading the servlet.
4. getServletConfig() :
- This method is used to return the servlet config object.
- This object contains the initialization parameters and startup configuration for this servlet.
- This method returns the ServletConfig object to init() method and the init() method will store this object in order to return ServletConfig object if needed.
5. getServletInfo() :
- This method returns a string that contains the information of the servlet such as version, copyright, author.
- This information is used as administrative tool and be displayed by the servlet engine.
- It returns this information in plain string form, as the information is servlet engine specific.
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