Servlet写java代码很好，但是拼接html的时候，非常不方便
JSP可以在html中嵌套java代码，这样在展示的时候，就会比较方便
Tomcat帮我们把jsp的页面翻译成了Servlet去运行的，查看目录
Tomcat目录workCatalinalocalhost
生成一个xxx_jsp.java的Servlet文件，jsp的脚本片段放在了_jspService()方法里面
使用eclipse创建项目以后，修改一下发布路径，直接发布到Tomcat的webapps目录下，
在Servers标签栏，先删除下面的项目，在右键点open，选择use Tomcat installation
jsp声明：<%! 若干java代码%>，此处的代码会解析到类的成员的地方
jsp注释：<%--注释的内容--%>
index.jsp
<%@page import="org.apache.jasper.tagplugins.jstl.core.Out"%> <%@page import="java.util.Date"%> <%@ page language="java" contentType="text/html; charset=utf-8" 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>首页</title> </head> <body> <%! public void test(){ int a=0; } %> <% for(int i=0;i<5;i++){ out.write(i+""); } %> <%-- Date date=new Date(); out.write(date.toLocaleString()); --%> 你好，JSP </body> </html>
index_jsp.java
public final class index_jsp extends org.apache.jasper.runtime.HttpJspBase implements org.apache.jasper.runtime.JspSourceDependent { public void test(){ int a=0; } 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; javax.servlet.http.HttpSession session = null; 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, true, 8192, true); _jspx_page_context = pageContext; application = pageContext.getServletContext(); config = pageContext.getServletConfig(); session = pageContext.getSession(); out = pageContext.getOut(); _jspx_out = out; out.write(" "); out.write(" "); out.write(" "); out.write("<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> "); out.write("<html> "); out.write("<head> "); out.write("<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> "); out.write("<title>首页</title> "); out.write("</head> "); out.write("<body> "); out.write(' '); out.write(' '); for(int i=0;i<5;i++){ out.write(i+""); } out.write(' '); out.write(' '); out.write(" "); out.write("你好，JSP "); out.write("</body> "); 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); } }