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jsp指令和动作

news 来源：原创 2024/4/28 8:54:51

1.page指令：描述页面信息

pageENcoding:软件编码

contentType：浏览器编码

2.include指令：将多个网页合成一个网页，静态包含网页

问题：1.在网页源代码中，会形成错误的多遍代码，将主页面代码和副页面各删除一半。

2.多个网页中的代码不能有任何冲突

<%@ page language="java" contentType="text/html; charset=UTF-8"pageEncoding="UTF-8"%>
<!DOCTYPE html>
<%@ include file ="NewFile.jsp" %><h3>这位是一个主网页1</h3>
<h3>这是另一个网页的变量：<%=a %></h3>
</body>
</html>

<%@ 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>
<h3>这是一个导航栏</h3>
<h3><% int a=12;%></h3>

查看网页源代码

完整代码

3.include动作

jsp动作:include,param,forward

基本语法:

1.<jsp:include page=""/>

2.<jsp:include page="">

包含网页传递数据

include指令：静态包含,代码复用，一起生成网页，

注意：被包含网页不需要写部分网页代码，一起编译执行，运行1次，运行效率高

include动作：动态包含，结果复用，共同生成网页，

注意：被包含网页不需要写结构网页代码，一起编译执行，运行多次，运行效率低

<%@ 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>
<jsp:include page="NewFile1.jsp"/>
<h3>这是一个网页1</h3>
</body>
</html>

<%@ page language="java" contentType="text/html; charset=UTF-8"pageEncoding="UTF-8"%>
<!DOCTYPE html><h3>次级网页</h3>

4.param动作

param动作：向其他网页传递数据

用法：<jsp:param value="值" name="值对应的名字">

注意事项：动作不能单独使用，要和其他动作一起使用

<%@ 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>
<jsp:include page="NewFile1.jsp">
<jsp:param value="18" name="age"/>
</jsp:include>
<h3>这是一个网页1</h3>
</body>
</html>

<%@ page language="java" contentType="text/html; charset=UTF-8"pageEncoding="UTF-8"%>
<!DOCTYPE html><h3>次级网页</h3>
<%String s = request.getParameter("age");out.print(s);%>

传递中文乱码:数据传输和数据接收编码

解决方法：在发送和接收的网页中添加<%request.setCharacterEncoding("UTF-8");%>

<%@ 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");%>
<jsp:include page="NewFile1.jsp">
<jsp:param value="12" name="id1"/>
<jsp:param value="12.34" name="id2"/>
<jsp:param value="张红" name="id3"/>
</jsp:include>
<h3>这是一个网页1</h3>
</body>
</html>

<%@ page language="java" contentType="text/html; charset=UTF-8"pageEncoding="UTF-8"%>
<!DOCTYPE html><h3>次级网页</h3>
<%request.setCharacterEncoding("UTF-8");String s = request.getParameter("id1");String s1 = request.getParameter("id2");String s2 = request.getParameter("id3");Double b = Double.parseDouble(s1)+10;//把s字符串转换为double类型Integer i=Integer.parseInt(s)+10;//首字母大写是类名String s5=b + "";out.print(s);out.print(s1);out.print(s2);
%>

forward:跳转到新页面

跳转到新页面

语法：1.<jsp:forward page=“relativeURL”>不用传参数

2.<jsp:forward page="要转向的页面" >

使用param动作传递数据

<jsp:param name= "paramterName" value= " parametrValue" />传参数

</jsp:forward>

注意：用forward跳转后的页面显示的网址是跳转之前的网页

执行forward代码后不在执行

<%@ 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><h3>这是主页面</h3><%-- <jsp:forward page="NewFile1.jsp"/>  --%><%request.setCharacterEncoding("UTF-8");%><jsp:forward page="NewFile1.jsp" ><jsp:param name= "张三"  value= "name" /></jsp:forward> <% request.setAttribute("id", "18");   %></body>
</html>

<%@ 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"); %> <h3>这是跳转网页</h3><%String s = request.getParameter("name");%><%out.print(request.getAttribute("id"));%><h3>登录成功，欢迎</h3>
</body>
</html>

<%@ 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><h3>这是主页面</h3><%-- <jsp:forward page="NewFile1.jsp"/>  --%><%request.setCharacterEncoding("UTF-8");%><% request.setAttribute("id", "18");   %><jsp:forward page="NewFile1.jsp" ><jsp:param name= "张三"  value= "name" /></jsp:forward> </body>
</html>