JSP内置对象request 常用方法案例

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JSP九大内置对象有 request,out,response,application,session,pageContext,page,confid,exception

下面我写一个关于request经典案例

1.request
1.1 getParameter("name"):String 获取提交过来的数据（表单，url地址中）

1.2 getParameterValues("name"):String[] 一批同名的value值的集合

1.3 setCharactorEncoding("utf-8"); post

1.4 getAttrubute("key")：Object 获取指定的key对应的value

1.5 setAttribute("key","value");

1.6 getRequestDispatcher("目标地址").forward(request,response);

1.7 获取远程计算机的ip getRemoteAddr();

<%@ page language="java" import="java.util.*" pageEncoding="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>注册页面</title>  </head>    <body>     <form action="do.jsp" method="post">     用户名：<input type="text" name="txtname"  value="<%=request.getAttribute("name")%>"/>     密码： <input type="password" name="txtpwd"/>       <input type="submit" value="提交"/>     </form>     </body></html>

do.jsp 代码如下

<%@ page language="java" import="java.util.*" pageEncoding="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>处理页面</title>  </head>    <body>     <%          //解决乱码          request.setCharacterEncoding("utf-8");         //    1.取出name属性  对应的value值     String name=request.getParameter("txtname");     //2.   取值      String pwd=request.getParameter("txtpwd");     if(name.equals("中文")&&pwd.equals("1")){     //作用域保存name     request.setAttribute("name", name);     //跳转操作     request.getRequestDispatcher("/index.jsp").forward(request,response);     }else{      request.setAttribute("name", name);      request.getRequestDispatcher("/register.jsp").forward(request,response);     }      %>  </body></html>

index.jsp代码如下

<%@ page language="java" import="java.util.*" pageEncoding="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>  </head>    <body>  欢迎<%=request.getAttribute("name")   %>  </body></html>

效果图如下当你刷新页面时会有一个null值这是因为在register.jsp中在用户名中直接写的value="<%=request.getAttribute("name")%>" 这里会返回一个null值要想解决这个问题用三元运算符

当你登录失败时会保留这个登录失败的用户名

当你成功时

0 1

JSP内置对象request 常用方法 案例

JSP内置对象request 常用方法案例