<!-- HTML注释 --> html注释被当作模版元素输出到了浏览器上,浏览器认识html注释不予显示
代码：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title></title>
<meta http-equiv=" pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
</head>
<!-- 去哪里看被翻译的jsp呢？tomcat目录的work目录下的localhost....找出相应的翻译的源代码 -->
<body>
<%--jsp表达式(不以分号结束)--> 在翻译过来的servlet直接计算出结果，使用out输出到浏览器中--%>
<%=1+1
%>
<%--jsp脚本片段-->直接拷贝内容到jsp被翻译的servlet中 --%>
<%
int i=0;
out.print(i);
%>
<%--jsp声明-->在翻译过来的servlet直接放到与service()方法同级的 位置，变成了类的成员--%>
<%!int j=7; %>
</body>
</html>
对应翻译的代码：package org.apache.jsp.jsp;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.*;
import java.util.*;
public final class jspDemo1_jsp extends org.apache.jasper.runtime.HttpJspBase
implements org.apache.jasper.runtime.JspSourceDependent {
int j=7;
private static final JspFactory _jspxFactory = JspFactory.getDefaultFactory();
private static java.util.List _jspx_dependants;
private javax.el.ExpressionFactory _el_expressionfactory;
private org.apache.AnnotationProcessor _jsp_annotationprocessor;
public Object getDependants() {
return _jspx_dependants;
}
public void _jspInit() {
_el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory();
_jsp_annotationprocessor = (org.apache.AnnotationProcessor) getServletConfig().getServletContext().getAttribute(org.apache.AnnotationProcessor.class.getName());
}
public void _jspDestroy() {
}
public void _jspService(HttpServletRequest request, HttpServletResponse response)
throws java.io.IOException, ServletException {
PageContext pageContext = null;
HttpSession session = null;
ServletContext application = null;
ServletConfig config = null;
JspWriter out = null;
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("\r\n");
out.write("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">\r\n");
out.write("<html>\r\n");
out.write(" <head>\r\n");
out.write(" \r\n");
out.write(" \r\n");
out.write(" <title></title>\r\n");
out.write(" \r\n");
out.write("\t<meta http-equiv=\" pragma\" content=\"no-cache\">\r\n");
out.write("\t<meta http-equiv=\"cache-control\" content=\"no-cache\">\r\n");
out.write("\t<meta http-equiv=\"expires\" content=\"0\"> \r\n");
out.write("\t\r\n");
out.write(" </head>\r\n");
out.write(" <!-- 去哪里看被翻译的jsp呢？--> -->\r\n");
out.write(" <body>\r\n");
out.write(" ");
out.write("\r\n");
out.write(" ");
out.print(1+1
);
out.write("\r\n");
out.write(" ");
out.write("\r\n");
out.write(" ");
int i=0;
out.print(i);
out.write("\r\n");
out.write(" ");
out.write("\r\n");
out.write(" ");
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);
}
}
}
我们可以看到j变量放在了与service 同级位置作为成员属性。i是service（）的方法的局部变量
对于表达式。直接计算。
原文：http://blog.csdn.net/u014010769/article/details/46551569