A servlet is a small Java program that runs within a Web server. Servlets receive and respond to requests from Web clients, usually across HTTP, the HyperText Transfer Protocol.
To implement this interface, you can write a generic servlet that extends jakarta.servlet.GenericServlet
or an HTTP servlet that extends jakarta.servlet.http.HttpServlet.
This interface defines methods to initialize a servlet, to service requests, and to remove a servlet from the server. These are known as life-cycle methods and are called in the following sequence:
init method.
service method are handled.
destroy method, then garbage collected
and finalized.
In addition to the life-cycle methods, this interface provides the getServletConfig method, which the
servlet can use to get any startup information, and the getServletInfo method, which allows the servlet
to return basic information about itself, such as author, version, and copyright.
GenericServlet, jakarta.servlet.http.HttpServlet
| Modifier and Type | Method and Description |
|---|---|
| public void | destroy()
Called by the servlet container to indicate to a servlet that the servlet is being taken out of service. |
| public ServletConfig | Returns: theServletConfig object that initializes this servletReturns a |
| public String | Returns: aString containing servlet informationReturns information about the servlet, such as author, version, and copyright. |
| public void | init(ServletConfig
a config)ServletConfig object containing the servlet's configuration and initialization
parametersCalled by the servlet container to indicate to a servlet that the servlet is being placed into service. |
| public void | service(ServletRequest
the req, ServletResponse ServletRequest object that contains the client's requestthe res)ServletResponse object that contains the servlet's responseCalled by the servlet container to allow the servlet to respond to a request. |
| destroy | back to summary |
|---|---|
| public void destroy() Called by the servlet container to indicate to a servlet that the servlet is being taken out of service. This
method is only called once all threads within the servlet's This method gives the servlet an opportunity to clean up any resources that are being held (for example, memory, file handles, threads) and make sure that any persistent state is synchronized with the servlet's current state in memory. | |
| getServletConfig | back to summary |
|---|---|
| public ServletConfig getServletConfig() Returns a
Implementations of this interface are responsible for storing the
| |
| getServletInfo | back to summary |
|---|---|
| public String getServletInfo() Returns information about the servlet, such as author, version, and copyright. The string that this method returns should be plain text and not markup of any kind (such as HTML, XML, etc.).
| |
| init | back to summary |
|---|---|
| public void init(ServletConfig config) throws ServletException Called by the servlet container to indicate to a servlet that the servlet is being placed into service.
The servlet container calls the
The servlet container cannot place the servlet into service if the
| |
| service | back to summary |
|---|---|
| public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException Called by the servlet container to allow the servlet to respond to a request.
This method is only called after the servlet's The status code of the response always should be set for a servlet that throws or sends an error. Servlets typically run inside multithreaded servlet containers that can handle multiple requests concurrently. Developers must be aware to synchronize access to any shared resources such as files, network connections, and as well as the servlet's class and instance variables. More information on multithreaded programming in Java is available in the Java tutorial on multi-threaded programming.
| |