jsp基础(二)之包含指令

最新推荐文章于 2021-10-25 18:30:05 发布

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本文详细介绍了静态包含和动态包含的概念、语法、实例及区别。通过代码示例展示了如何在网页中实现页面的静态与动态包含，并讨论了它们在实际应用中的优劣。

说明：包含指令分为静态包含和动态包含

静态包含

语法：<@ include file="页面路径"/>

实例：include.jsp文件静态包含info.jsp 和info.html两个文件

info.jsp代码文件

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<h1>info.jsp</h1>
</body>
</html>

info.html代码文件

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1>info.html</h1>
</body>
</html>

include.jsp代码文件

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
+++++++++++++++++++++++++++++++++
<%@ include file="info.html" %>
+++++++++++++++++++++++++++++++++
<%@ include file="info.jsp" %>
+++++++++++++++++++++++++++++++++
</body>
</html>

我们访问include.jsp页面后查看页面源代码如下：

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
+++++++++++++++++++++++++++++++++
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1>info.html</h1>
</body>
</html>
+++++++++++++++++++++++++++++++++

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<h1>info.jsp</h1>
</body>
</html>
+++++++++++++++++++++++++++++++++
</body>
</html>

总结：从上面的代码可以看出，静态包含指令就是直接把所包含的页面原封不动的拿过来。然后再编译输出，如果两个页面中定义了相同的变量名称。那么页面就会出错（实例中未演示）。

口诀：静态包含先包含再处理

动态包含

语法：

<jsp:include page="info2.jsp">
 <jsp:param value="Tom" name="userName"/>
 <jsp:param value="123" name="password"/>
</jsp:include>
=============================================
<jsp:include page="info2.html"></jsp:include>

实例：include2.jsp动态包含两个页面，分别是info2.html 和info2.jsp 其中info2.html文件和上面的info.htm的内容一致。剩余两个文件的内容如下：

include2.jsp页面代码：

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
=============================================
<jsp:include page="info2.jsp">
 <jsp:param value="Tom" name="userName"/>
 <jsp:param value="123" name="password"/>
</jsp:include>
=============================================
<jsp:include page="info2.html"></jsp:include>
</body>
</html>

info2.jsp页面代码：

<%@ page language="java" contentType="text/html;"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
</head>
<body>
<h1>info2.jsp</h1>
<%
String userName=request.getParameter("userName");
String password=request.getParameter("password"); 

%>
用户名：<%=userName %>
<br/>密码：<%=password %>
</body>
</html>

总结：info2.jsp将接收到include2.jsp传递过来的用户名和密码。当这两个页面中定义的变量名称相同时，页面不会出错（实例中未演示）

口诀：动态包含先处理再包含