jsp本质是一个servlet！！！
所以可以在jsp中写java代码，在访问jsp的时候，其实就是响应了一个servlet的请求
附上部分源码：
public void _jspService(final javax.servlet.http.HttpServletRequest request, final javax.servlet.http.HttpServletResponse response)
throws java.io.IOException, javax.servlet.ServletException {
final javax.servlet.jsp.PageContext pageContext;
final javax.servlet.ServletContext application;
final javax.servlet.ServletConfig config;
javax.servlet.jsp.JspWriter out = null;
final java.lang.Object page = this;
javax.servlet.jsp.JspWriter _jspx_out = null;
javax.servlet.jsp.PageContext _jspx_page_context = null;
try {
response.setContentType("text/html; charset=UTF-8");
pageContext = _jspxFactory.getPageContext(this, request, response,
null, false, 8192, true);
_jspx_page_context = pageContext;
application = pageContext.getServletContext();
config = pageContext.getServletConfig();
out = pageContext.getOut();
_jspx_out = out;
out.write("
");
out.write("
");
java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat("yyyy");
request.setAttribute("year", sdf.format(new java.util.Date()));
request.setAttribute("tomcatUrl", "http://tomcat.apache.org/");
request.setAttribute("tomcatDocUrl", "/docs/");
request.setAttribute("tomcatExamplesUrl", "/examples/");
out.write("
");
out.write("<!DOCTYPE html>
");
out.write("<html lang="en">
");
out.write(" <head>
");
out.write(" <meta charset="UTF-8" />
");
out.write(" <title>");
out.print(request.getServletContext().getServerInfo() );
out.write("</title>
");
out.write(" <link href="favicon.ico" rel="icon" type="image/x-icon" />
");
out.write(" <link href="favicon.ico" rel="shortcut icon" type="image/x-icon" />
");
out.write(" <link href="tomcat.css" rel="stylesheet" type="text/css" />
");
out.write(" </head>
");
out.write("
");
out.write(" <body>
");
out.write(" <div id="wrapper">
");
out.write(" <div id="navigation" class="curved container">
");
out.write(" <span id="nav-home"><a href="");
out.write((java.lang.String) org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate("${tomcatUrl}", java.lang.String.class, (javax.servlet.jsp.PageContext)_jspx_page_context, null, false));
out.write("">Home</a></span>
");
out.write("</html>
");
} catch (java.lang.Throwable t) {
if (!(t instanceof javax.servlet.jsp.SkipPageException)){
out = _jspx_out;
if (out != null && out.getBufferSize() != 0)
try {
if (response.isCommitted()) {
out.flush();
} else {
out.clearBuffer();
}
} catch (java.io.IOException e) {}
if (_jspx_page_context != null) _jspx_page_context.handlePageException(t);
else throw new ServletException(t);
}
} finally {
_jspxFactory.releasePageContext(_jspx_page_context);
}
}
}
～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～
下面学习jsp的语法：
jsp模版元素--------》html标签，模版元素
jsp脚本表达式--------》用于向浏览器输出数据
<body>
<form action="/day06/DoFormServlet" method="post ">
<%@ page import="java.util.Date"%>
<%
Date date=new Date();
String time=date.toLocaleString();
out.write("out方式输出:"+"<br/>");
out.write(time);
%>
<br/>
<% out.write("<%=方式输出"+"<br/>"); %>
<%= time%>
</body>
jsp脚本片段--------》如上代码 <% java代码 %>
jsp声明----------》就是<%! java代码%> 这段代码会加到service方法外！
jsp注释-----------》<%- dfsdfsdf -%>
html/xml注释--------》<!-- -->(会打给浏览器，但是不显示，会产生代码垃圾)
jsp指令----》jsp指令是为jsp引擎而设计的
1.page指令
2.Include指令
3.taglib指令
<%@ 指令 属性名=“值” %>
举例：<%@ page import="java.util.Date"%>
不产生可见输出
1.page指令
2.include指令
静态包含的性能会好很多，编译时包含是把所有jsp的编译成一个servlet
动态是把所需要的运行包含，每个jsp都有一个servlet
静态包含：
动态包含；
九大隐士对象：
request
response
session
application
config
page
out
exception
pagecontext
jsp最特殊的是pagecontext：
pagecontext可以调到其他八大隐式对象，所以可以通过这一个对象得到其他八个的值
jsp常用标签：
<jsp:forward page=""></jsp:forward> <jsp:include page=""></jsp:include>
<jsp:param name="" value="">
jsp映射：
把14.jsp映射到15.html，也就是访问15.html看到的是14.jsp
