请求转发和重定向-蒲公英云

请求转发和重定向

请求转发

A向B请求资源，B没有该资源，于是B向C请求该资源。C将资源返回给B，B将资源返回给A。

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
         // Attribute涉及servlet之间的传参
         request.setAttribute("name", "lsk");    
                 // 将请求传递给s2，s2是xml文件中设置的另一个servlet的<url-pattern>             
         request.getRequestDispatcher("s2").forward(request, response);
    }
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {            
        String u_name = (String)request.getAttribute("name");
        response.getWriter().append("name:").append(u_name);
}

特点：参数共享，一次请求，地址不变

重定向

A向B请求资源，B没有该资源，B告诉A：C有你要的资源。于是A向C请求资源，C将资源返回给A。

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {     
         // 返回给请求方资源拥有者s2
         response.sendRedirect("s2");
    }
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {            
        String u_name = (String)request.getAttribute("name");
        response.getWriter().append("name:").append(u_name);
}