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Servlet (Servlet and JavaServer Pages API Documentation)
javax.servlet
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Method Summary | |
void |
destroy()
Called by the servlet container to indicate to a servlet that the servlet is being taken out of service. |
ServletConfig |
getServletConfig()
Returns a ServletConfig object, which contains
initialization and startup parameters for this servlet.
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java.lang.String |
getServletInfo()
Returns information about the servlet, such as author, version, and copyright. |
void |
init(ServletConfig config)
Called by the servlet container to indicate to a servlet that the servlet is being placed into service. |
void |
service(ServletRequest req,
ServletResponse res)
Called by the servlet container to allow the servlet to respond to a request. |
Method Detail |
public void init(ServletConfig config) throws ServletException
The servlet container calls the init
method exactly once after instantiating the servlet.
The init
method must complete successfully
before the servlet can receive any requests.
The servlet container cannot place the servlet into service
if the init
method
ServletException
config
- a ServletConfig
object
containing the servlet's
configuration and initialization parameters
ServletException
- if an exception has occurred that
interferes with the servlet's normal
operationUnavailableException
,
getServletConfig()
public ServletConfig getServletConfig()
ServletConfig
object, which contains
initialization and startup parameters for this servlet.
The ServletConfig
object returned is the one
passed to the init
method.
Implementations of this interface are responsible for storing the
ServletConfig
object so that this
method can return it. The GenericServlet
class, which implements this interface, already does this.
ServletConfig
object
that initializes this servletinit(javax.servlet.ServletConfig)
public void service(ServletRequest req, ServletResponse res) throws ServletException, java.io.IOException
This method is only called after the servlet's init()
method has completed successfully.
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.
req
- the ServletRequest
object that contains
the client's requestres
- the ServletResponse
object that contains
the servlet's response
ServletException
- if an exception occurs that interferes
with the servlet's normal operation
java.io.IOException
- if an input or output exception occurspublic java.lang.String getServletInfo()
The string that this method returns should be plain text and not markup of any kind (such as HTML, XML, etc.).
String
containing servlet informationpublic void destroy()
service
method have exited or after a timeout
period has passed. After the servlet container calls this
method, it will not call the service
method again
on this servlet.
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.
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