public abstract class HttpFilter extends GenericFilter
Provides an abstract class to be subclassed to create an HTTP filter suitable for a Web site. A subclass of
HttpFilter should override
doFilter(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, javax.servlet.FilterChain).
Filters typically run on multithreaded servers, so be aware that a filter must handle concurrent requests and be careful to synchronize access to shared resources. Shared resources include in-memory data such as instance or class variables and external objects such as files, database connections, and network connections. See the Java Tutorial on Multithreaded Programming for more information on handling multiple threads in a Java program.
| Constructor and Description |
|---|
HttpFilter()
Does nothing, because this is an abstract class.
|
| Modifier and Type | Method and Description |
|---|---|
protected void |
doFilter(HttpServletRequest req,
HttpServletResponse res,
FilterChain chain)
The
doFilter method of the Filter is called by the container each time a request/response pair is
passed through the chain due to a client request for a resource at the end of the chain. |
void |
doFilter(ServletRequest req,
ServletResponse res,
FilterChain chain)
The
doFilter method of the Filter is called by the container each time a request/response pair is
passed through the chain due to a client request for a resource at the end of the chain. |
getFilterConfig, getFilterName, getInitParameter, getInitParameterNames, getServletContext, init, initpublic HttpFilter()
Does nothing, because this is an abstract class.
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws java.io.IOException, ServletException
The doFilter method of the Filter is called by the container each time a request/response pair is
passed through the chain due to a client request for a resource at the end of the chain. The FilterChain passed
in to this method allows the Filter to pass on the request and response to the next entity in the chain. There's
no need to override this method.
The default implementation inspects the incoming req and res objects to determine if they are
instances of HttpServletRequest and HttpServletResponse, respectively. If not, a
ServletException is thrown. Otherwise, the protected
doFilter(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, javax.servlet.FilterChain)
method is called.
req - a ServletRequest object that contains the request the client has made of the filterres - a ServletResponse object that contains the response the filter sends to the clientchain - the FilterChain for invoking the next filter or the resourcejava.io.IOException - if an input or output error is detected when the filter handles the requestServletException - if the request for the could not be handled or either parameter is not an instance of
the respective HttpServletRequest or HttpServletResponse.UnavailableExceptionprotected void doFilter(HttpServletRequest req, HttpServletResponse res, FilterChain chain) throws java.io.IOException, ServletException
The doFilter method of the Filter is called by the container each time a request/response pair is
passed through the chain due to a client request for a resource at the end of the chain. The FilterChain passed
in to this method allows the Filter to pass on the request and response to the next entity in the chain.
The default implementation simply calls FilterChain.doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse)
req - a HttpServletRequest object that contains the request the client has made of the filterres - a HttpServletResponse object that contains the response the filter sends to the clientchain - the FilterChain for invoking the next filter or the resourcejava.io.IOException - if an input or output error is detected when the filter handles the requestServletException - if the request for the could not be handled