forward redirect 本质区别

tomcat源码：



----------------------redirect-------------------------------



try {
            String absolute = toAbsolute(location);
            setStatus(SC_FOUND);
            setHeader("Location", absolute);
} catch (IllegalArgumentException e) {
            setStatus(SC_NOT_FOUND);
}



其中：
  /**
    * Status code (302) indicating that the resource reside
    * temporarily under a different URI. Since the redirection might
    * be altered on occasion, the client should continue to use the
    * Request-URI for future requests.(HTTP/1.1) To represent the
    * status code (302), it is recommended to use this variable.
    */
public static final int SC_FOUND = 302;



-----------------------------------forward-------------------------------------------



ApplicationDispatcher.forward

-->ApplicationDispatcher.doForward

-->ApplicationDispatcher.processRequest(request,response)

-->ApplicationDispatcher.invoke(outerRequest, response)

-->filterChain.doFilter(request, response)

-->filter.doFilter(request, response, this)

.....N个filter,最后-->

-->servlet.service(request, response);



重新过了一遍 filter,servlet