JSP全名为Java Server Pages,java服务器页面。JSP是一种基于文本的程序,其特点就是HTML和Java代码共同存在!
JSP是为了简化Servlet的工作出现的替代品,Servlet输出HTML非常困难,JSP就是替代Servlet输出HTML的。
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>简单使用JSP</title>
</head>
<body>
</body>
</html>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>简单使用JSP</title>
</head>
<body>
<%
String s = "HelloWorld";
out.println(s);
%>
</body>
</html>
package org.apache.jsp;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.*;
import java.util.Date;
public final class _1_jsp extends org.apache.jasper.runtime.HttpJspBase
implements org.apache.jasper.runtime.JspSourceDependent {
private static final JspFactory _jspxFactory = JspFactory.getDefaultFactory();
private static java.util.List<String> _jspx_dependants;
private javax.el.ExpressionFactory _el_expressionfactory;
private org.apache.tomcat.InstanceManager _jsp_instancemanager;
public java.util.List<String> getDependants() {
return _jspx_dependants;
}
public void _jspInit() {
_el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory();
_jsp_instancemanager = org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(getServletConfig());
}
public void _jspDestroy() {
}
public void _jspService(final HttpServletRequest request, final HttpServletResponse response)
throws java.io.IOException, ServletException {
final PageContext pageContext;
HttpSession session = null;
final ServletContext application;
final ServletConfig config;
JspWriter out = null;
final Object page = this;
JspWriter _jspx_out = null;
PageContext _jspx_page_context = null;
try {
response.setContentType("text/html;charset=UTF-8");
pageContext = _jspxFactory.getPageContext(this, request, response,
null, true, 8192, true);
_jspx_page_context = pageContext;
application = pageContext.getServletContext();
config = pageContext.getServletConfig();
session = pageContext.getSession();
out = pageContext.getOut();
_jspx_out = out;
out.write("\r\n");
out.write("\r\n");
out.write("<html>\r\n");
out.write("<head>\r\n");
out.write(" <title>简单使用JSP</title>\r\n");
out.write("</head>\r\n");
out.write("<body>\r\n");
String s = "HelloWorda";
out.println(s);
out.write("\r\n");
out.write("</body>\r\n");
out.write("</html>\r\n");
} catch (Throwable t) {
if (!(t instanceof SkipPageException)){
out = _jspx_out;
if (out != null && out.getBufferSize() != 0)
try { out.clearBuffer(); } catch (java.io.IOException e) {}
if (_jspx_page_context != null) _jspx_page_context.handlePageException(t);
}
} finally {
_jspxFactory.releasePageContext(_jspx_page_context);
}
}
}
out.write("\r\n");
out.write("\r\n");
out.write("<html>\r\n");
out.write("<head>\r\n");
out.write(" <title>简单使用JSP</title>\r\n");
out.write("</head>\r\n");
out.write("<body>\r\n");
String s = "HelloWorda";
out.println(s);
JSP也是Servlet,运行时只有一个实例,JSP初始化和销毁时也会调用Servlet的init()和destroy()方法。另外,JSP还有自己初始化和销毁的方法
public void _jspInit() {
_el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory();
_jsp_instancemanager = org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(getServletConfig());
}
public void _jspDestroy() {
}
JSP代码可以分为两部分:
<jsp:scriptlet>
String s = "HelloWorld";
out.println(s);
</jsp:scriptlet>
<%--这是JSP注释--%>
<%--%>
//这是java的当行注释
//
/*这是java的多行注释*/
/**/
JSP指令用来声明JSP页面的相关属性,例如编码方式、文档类型等等
JSP指令的语法:
<%@指令 属性名="值" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page contentType="application/msword;charset=UTF-8" language="java" %>
<html>
<head>
<title>简单使用JSP</title>
</head>
<body>
1111
</body>
</html>
<%@ page contentType="text/html;charset=UTF-8" language="java" errorPage="error.jsp" %>
<html>
<head>
<title>该页面出错了!</title>
</head>
<body>
<%--模拟页面出错了!!!--%>
<%
int result = 2 / 0;
%>
你好呀
</body>
</html>
<%@ page contentType="text/html;charset=UTF-8" language="java" isErrorPage="true" %>
<html>
<head>
<title>友好提示页面</title>
</head>
<body>
服务器正忙着呢!
</body>
</html>
<error-page>
<error-code>404</error-code>
<location>/error.jsp</location>
</error-page>
<error-page>
<exception-type>java.lang.NullPointerException</exception-type>
<location>/error.jsp</location>
</error-page>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>页头</title>
</head>
<body>
我是页头
<br>
<br>
<br>
</body>
</html>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>页尾</title>
</head>
<body>
我是页尾
</body>
</html>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>包含页头和页尾进来</title>
</head>
<body>
<%@include file="head.jsp" %>
<%@include file="foot.jsp" %>
</body>
</html>
JSP行为(JSP Actions)是一组JSP内置的标签,只书写少量的标记代码就能够使用JSP提供丰富的功能,JSP行为是对常用的JSP功能的抽象和封装。
为什么我不把它直接称为JSP标签呢?我把这些JSP内置的标签称之为JSP行为,能够和JSTL标签区分开来。当然了,你也可以把它称之为JSP标签,你不要搞混就行了。我个人喜欢把这些JSP内置标签称之为JSP行为。
<jsp:include page=""/>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>包含页头和页尾进来</title>
</head>
<body>
<jsp:include page="head.jsp"/>
<jsp:include page="foot.jsp"/>
</body>
</html>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>页头</title>
</head>
<body>
<%
String s = "zhongfucheng";
%>
我是页头呀
<br>
<br>
<br>
</body>
</html>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>页尾</title>
</head>
<body>
<%
String s = "zhongfucheng";
%>
我是页尾呀
</body>
</html>
<jsp:forward page=""/>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>访问1.jsp就跳转到head.jsp</title>
</head>
<body>
<jsp:forward page="head.jsp"/>
</body>
</html>
<jsp:forward page="head.jsp">
<jsp:param name="username" value="zhongfucheng"/>
</jsp:forward>
<%
String ss = request.getParameter("username");
%>
获取到的参数是:
<%=ss%>
<jsp:directive.include file="head.jsp"></jsp:directive.include>
<jsp:directive.include file="foot.jsp"></jsp:directive.include>
<jsp:scriptlet>
替代<%%>是同样一个道理<jsp:useBean id=""/>
<jsp:setProperty name="" property=""/>
<jsp:getProperty name="" property=""/>
如果文章有错的地方欢迎指正,大家互相交流。