请求重定向与请求转发的区别

一 请求重定向与请求转发的区别

 

 

 

二 生活小案例

 

 

 

三 请求转发实例(reg.jsp->response.jsp->request.jsp)

1、reg.jsp

<%@  page  language = "java"  import = "java.util.*"  contentType = "text/html; charset=utf-8" %>

<%

String path = request.getContextPath();

String basePath = request.getScheme()+ "://" +request.getServerName()+ ":" +request.getServerPort()+path+ "/" ;

%>

 

<! DOCTYPE  HTML  PUBLIC  "-//W3C//DTD HTML 4.01 Transitional//EN">

< html >

   < head >

     < base  href = " <%= basePath %> " >

   

     < title > My JSP 'index.jsp' starting page </ title >

         < meta  http-equiv = "pragma"  content = "no-cache" >

         < meta  http-equiv = "cache-control"  content = "no-cache" >

         < meta  http-equiv = "expires"  content = "0" >    

         < meta  http-equiv = "keywords"  content = "keyword1,keyword2,keyword3" >

         < meta  http-equiv = "description"  content = "This is my page" >

         <!--

        <link  rel =" stylesheet " type="text/ css "  href ="styles.css">

        -->

   </ head >

 

   < body >

     < h1 > 用户注册 </ h1 >

     < hr >

     <%

        int  number=-1;

        //说明用户第一次访问页面，计数器对象还未创建

        if (application.getAttribute( "counter" )== null )

       {

           application.setAttribute( "counter" , 0);

       }

       number = Integer.parseInt(application.getAttribute( "counter" ).toString());

       number++;

       application.setAttribute( "counter" , number);

     %>

     <!-- <form name="regForm" action="request.jsp" method="post"> -->

     < form  name = "regForm"  action = "response.jsp"  method = "post" >

     < table >

       < tr >

         < td > 用户名： </ td >

         < td >< input  type = "text"  name = "username" /></ td >

       </ tr >

       < tr >

         < td > 爱好： </ td >

         < td >

            < input  type = "checkbox"  name = "favorite"  value = "read" > 读书

            < input  type = "checkbox"  name = "favorite"  value = "music" > 音乐

            < input  type = "checkbox"  name = "favorite"  value = "movie" > 电影

            < input  type = "checkbox"  name = "favorite"  value = "internet" > 上网

         </ td >

       </ tr >

       < tr >

          < td  colspan = "2" >< input  type = "submit"  value = "提交" /></ td >

       </ tr >

     </ table >

     </ form >

     < br >

     < br >

     < a  href = "request.jsp?username=李四" > 测试URL传参数 </ a >

   

     < br >

     < br >

     < center >

             您是第 <%= number  %> 位访问本页面的用户。

     </ center >

   </ body >

</ html >

2、response.jsp

<%@  page  language = "java"  import = "java.util.*,java.io.*"  contentType = "text/html; charset=utf-8" %>

<%

    response.setContentType( "text/html;charset=utf-8" );  //设置响应的MIMI类型

   

    out.println( "<h1>response内置对象</h1>" );

    out.println( "<hr>" );

     //out.flush();  //解决PrintWrite对象的浏览器输出总是先于out对象输出这一问题

   

    PrintWriter outer = response.getWriter();  //获得输出流对象

    outer.println( "大家好，我是response对象生成的输出流outer对象" );

     //response.sendRedirect("reg.jsp");//请求重定向

     //请求重定向

     //response.sendRedirect("request.jsp");

     //请求转发

    request.getRequestDispatcher( "request.jsp" ).forward(request, response);

%>

3、request .jsp

<%@   page   language = "java"   import = "java.util.*"   contentType = "text/html; charset=utf-8" %>

<%

String path = request.getContextPath();

String basePath = request.getScheme()+ "://" +request.getServerName()+ ":" +request.getServerPort()+path+ "/" ;

%>

 

<! DOCTYPE  HTML  PUBLIC  "-//W3C//DTD HTML 4.01 Transitional//EN">

< html >

   < head >

     < base  href = " <%= basePath %> " >

   

     < title > My JSP 'index.jsp' starting page </ title >

         < meta  http-equiv = "pragma"  content = "no-cache" >

         < meta  http-equiv = "cache-control"  content = "no-cache" >

         < meta  http-equiv = "expires"  content = "0" >    

         < meta  http-equiv = "keywords"  content = "keyword1,keyword2,keyword3" >

         < meta  http-equiv = "description"  content = "This is my page" >

         <!--

        <link  rel =" stylesheet " type="text/ css "  href ="styles.css">

        -->

   </ head >

 

   < body >

     < h1 > request内置对象 </ h1 >

     <%

       request.setCharacterEncoding( "utf-8" );  //解决中文乱码问题，无法解决URL传递中文出现的乱码问题。

       request.setAttribute( "password" ,  "123456" );

   

     %>

        用户名： <%= request.getParameter( "username" )  %> < br >   

        爱好 ： <%

            if (request.getParameterValues( "favorite" )!= null )

           {

                   String[] favorites = request.getParameterValues( "favorite" );

                    for ( int  i=0;i<favorites.length;i++)

                   {

                      out.println(favorites[i]+ "&nbsp;&nbsp;" );

                   }

                }

         %>  < br >

         密码： <%= request.getAttribute( "password" )  %> < br >

         请求体的MIME类型: <%= request.getContentType()  %> < br >

         协议类型及版本号:   <%= request.getProtocol()  %> < br >

         服务器主机名 : <%= request.getServerName()  %> < br >

         服务器端口号： <%= request.getServerPort()  %> < BR >

         请求文件的长度 ： <%= request.getContentLength()  %> < BR >

         请求客户端的IP地址： <%= request.getRemoteAddr()  %> < BR >

         请求的真实路径： <%= request. getRealPath( "request.jsp" )  %> < br >

         请求的上下文路径： <%= request.getContextPath()  %> < BR >                          

   </ body >

</ html >

 

四 运行结果