login.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
     <form action="check.jsp" >
          用户名：<input type="text" name="uname"><br/>
           密码：<input type="password" name="upwd"><br/>  
           <input type="submit"  value="登录"><br/>  
     </form>
</body>
</html>

check.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
      <%
         request.setCharacterEncoding("utf-8");
       String name = request.getParameter("uname");
       String pwd = request.getParameter("upwd");
       if(name.equals("zs")&&pwd.equals("abc"))
       {
           response.sendRedirect("success.jsp");
       }
       else
       {
           out.print("用户名或者密码失败");
       }
      %>
</body>
</html>

success.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
      登录成功！<br/>
      欢迎您：
      <%
      String name =request.getParameter("uname");
      out.print(name);
      %>
</body>
</html>

重定向与请求转发的区别_用户名

重定向与请求转发的区别_html_02

重定向与请求转发的区别_用户名_03

这里的null表示页面元素丢失了。

现在修改转发的方式：

check.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
      <%
         request.setCharacterEncoding("utf-8");
       String name = request.getParameter("uname");
       String pwd = request.getParameter("upwd");
       if(name.equals("zs")&&pwd.equals("abc"))
       {
           //response.sendRedirect("success.jsp");
           request.getRequestDispatcher("success.jsp").forward(request,response);
       }
       else
       {
           out.print("用户名或者密码失败");
       }
      %>
</body>
</html>

重定向与请求转发的区别_html_04