Eclipse中JSP生成的class文件去了哪里？
大家都知道，JSP在请求的时候，会先转化成Servlet（其实就是个java类），然后生成class文件，再提供服务。
那么生成的java、class文件在哪呢？Eclipse中根本找不到呀！
首先应该了解的是Tomcat在Eclipse的映射关系，参考前一篇博文所述：Tomcat的服务器目录配置
可以了解到，Tomcat在Eclipse中提供了三种位置配置选项：
1 Use workspace metadata
2 Use Tomcat installation
3 Use custom location
分别对应三种情况说一下，注意要把Server中发布的目录全部删除，然后clean后才能修改该配置项。
如果你在Eclipse中双击Server配置选项，在Server Location中分别选了如下的选项：
如果Server Locations选择了第一项Use workspace metadata
选了上面这项，你的服务器目录和发布目录将会如下：
服务器目录，即生成的字节码和java文件所在的目录。它在你的eclipse的工作目录中，比如我的工作目录是在F://workspace，那么在该目录下就可以看到这个.metadata目录了。
参考上面的配置目录F:\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0
这就是Tomcat映射的目录，在这个目录中有一个work目录和一个wtpwebapps目录
work目录中顺着：work\Catalina\localhost\项目名字\org\apache\jsp 就可以找到你的项目对应的java文件和class文件（注意要访问jsp后才会出现！）
wtpwebapps目录则存放对应的部署资源文件
如果选择的是第二项，Use Tomcat installation
如果勾选的use tomcat installation，那么你的tomcat目录将被选定为tomcat所安装的目录。
还是推荐选择这个吧，毕竟好找一点。
如果勾选第三项，Use custom location
目录的结构与上面的类似，上面这两个都是不可以修改的，要么是workspace所在的目录，要么是tomcat的目录。
选择该项，可以自定义生成的空间。
另外说一点，JSP的生命周期
这是老生常谈的问题了，用户把工程部署到tomcat中，然后启动tomcat！此时就可以访问jsp了、
1 第一次访问JSP，会验证一下是否第一次访问，然后把JSP转化成java(Servlet),再编译成class文件。
2 生成的class文件中会自动生成几个方法：jspInit()、jspDestroy()、jspService().Tomcat仅仅在第一次请求时，调用jspInit方法，然后调用jspService进行处理。
3 之后的每个请求，都会分配一个线程调用jspService方法。
4 如果页面被销毁或者关闭，都会调用jspDestroy
由于该文件是常驻内存的，又是多线程调用，所以访问的效率和速度都会很快。
按照前面所述的方法，就可以看到生成的文件结构了。
按照前面所述的方法，就可以看到生成的文件结构了。
为了展示，这里给出一个样例的JSP
<%@ page language="java" import="java.util.*,java.io.*" contentType="text/html; charset=utf-8"%>
???<%--
???language 脚本使用的语言
???import 加载类文件
???contentType 编码方式
????--%>
<!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>JSP</h1>
???
???<!-- 客户端可见 -->
???<%-- 客户端不可见 --%>
???<%!
???????String s = "xingoo";//声明变量
???????int add(int a,int b){//声明函数
???????????return a+b;
???????}
???%>
???s=<%=s %><br> <%--表达式不以分号结束 --%>
???1+2=<%=add(1,2) %><br>
???<%
???????//单行注释 ————————————————快捷键ctrl+/
???????/* 多行注释 ____________快捷键ctrl+shift+/ */
???????out.println("s="+s+"<br>");
???%>
</body>
</html>
里面含有一些注释，变量声明和打印输出等等。
在生成.java文件中，可以看到生成的java文件：
package org.apache.jsp;import javax.servlet.*;import javax.servlet.http.*;import javax.servlet.jsp.*;import java.util.*;import java.io.*;public final class test1_jsp extends org.apache.jasper.runtime.HttpJspBase ???implements org.apache.jasper.runtime.JspSourceDependent { ???????String s = "xingoo";//声明变量 ???????int add(int a,int b){//声明函数 ???????????return a+b; ???????} ?????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‘); ?????out.write(‘\n‘); ?????out.write(‘ ???‘); ?????out.write("\r\n"); ?????out.write("<!DOCTYPE html PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\" \"http://www.w3.org/TR/html4/loose.dtd\">\r\n"); ?????out.write("<html>\r\n"); ?????out.write("<head>\r\n"); ?????out.write("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\">\r\n"); ?????out.write("<title>Insert title here</title>\r\n"); ?????out.write("</head>\r\n"); ?????out.write("<body>\r\n"); ?????out.write("\t<h1>JSP</h1>\r\n"); ?????out.write("\t\r\n"); ?????out.write("\t<!-- 客户端可见 -->\r\n"); ?????out.write("\t"); ?????out.write(‘\r‘); ?????out.write(‘\n‘); ?????out.write(‘ ???‘); ?????out.write("\r\n"); ?????out.write("\ts="); ?????out.print(s ); ?????out.write("<br> "); ?????out.write("\r\n"); ?????out.write("\t1+2="); ?????out.print(add(1,2) ); ?????out.write("<br>\r\n"); ?????out.write("\t"); ???????//单行注释 ————————————————快捷键ctrl+/ ???????/* 多行注释 ____________快捷键ctrl+shift+/ */ ????????out.println("s="+s+"<br>"); ?????????out.write("\r\n"); ?????out.write("</body>\r\n"); ?????out.write("</html>"); ???} 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); ???????else log(t.getMessage(), t); ?????} ???} finally { ?????_jspxFactory.releasePageContext(_jspx_page_context); ???} ?}}package org.apache.jsp;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.*;
import java.util.*;
import java.io.*;
public final class test1_jsp extends org.apache.jasper.runtime.HttpJspBase
???implements org.apache.jasper.runtime.JspSourceDependent {
???????String s = "xingoo";//声明变量
???????int add(int a,int b){//声明函数
???????????return a+b;
???????}
???
?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‘);
?????out.write(‘\n‘);
?????out.write(‘ ???‘);
?????out.write("\r\n");
?????out.write("<!DOCTYPE html PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\" \"http://www.w3.org/TR/html4/loose.dtd\">\r\n");
?????out.write("<html>\r\n");
?????out.write("<head>\r\n");
?????out.write("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\">\r\n");
?????out.write("<title>Insert title here</title>\r\n");
?????out.write("</head>\r\n");
?????out.write("<body>\r\n");
?????out.write("\t<h1>JSP</h1>\r\n");
?????out.write("\t\r\n");
?????out.write("\t<!-- 客户端可见 -->\r\n");
?????out.write("\t");
?????out.write(‘\r‘);
?????out.write(‘\n‘);
?????out.write(‘ ???‘);
?????out.write("\r\n");
?????out.write("\ts=");
?????out.print(s );
?????out.write("<br> ");
?????out.write("\r\n");
?????out.write("\t1+2=");
?????out.print(add(1,2) );
?????out.write("<br>\r\n");
?????out.write("\t");
???????//单行注释 ————————————————快捷键ctrl+/
???????/* 多行注释 ____________快捷键ctrl+shift+/ */
???????out.println("s="+s+"<br>");
???
?????out.write("\r\n");
?????out.write("</body>\r\n");
?????out.write("</html>");
???} 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);
???????else log(t.getMessage(), t);
?????}
???} finally {
?????_jspxFactory.releasePageContext(_jspx_page_context);
???}
?}
}
声明注释，都可以很详细的看到。
package org.apache.jsp;import javax.servlet.*;import javax.servlet.http.*;import javax.servlet.jsp.*;import java.util.*;import java.io.*;public final class test1_jsp extends org.apache.jasper.runtime.HttpJspBase ???implements org.apache.jasper.runtime.JspSourceDependent { ???????String s = "xingoo";//声明变量 ???????int add(int a,int b){//声明函数 ???????????return a+b; ???????} ?????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‘); ?????out.write(‘\n‘); ?????out.write(‘ ???‘); ?????out.write("\r\n"); ?????out.write("<!DOCTYPE html PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\" \"http://www.w3.org/TR/html4/loose.dtd\">\r\n"); ?????out.write("<html>\r\n"); ?????out.write("<head>\r\n"); ?????out.write("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\">\r\n"); ?????out.write("<title>Insert title here</title>\r\n"); ?????out.write("</head>\r\n"); ?????out.write("<body>\r\n"); ?????out.write("\t<h1>JSP</h1>\r\n"); ?????out.write("\t\r\n"); ?????out.write("\t<!-- 客户端可见 -->\r\n"); ?????out.write("\t"); ?????out.write(‘\r‘); ?????out.write(‘\n‘); ?????out.write(‘ ???‘); ?????out.write("\r\n"); ?????out.write("\ts="); ?????out.print(s ); ?????out.write("<br> "); ?????out.write("\r\n"); ?????out.write("\t1+2="); ?????out.print(add(1,2) ); ?????out.write("<br>\r\n"); ?????out.write("\t"); ???????//单行注释 ————————————————快捷键ctrl+/ ???????/* 多行注释 ____________快捷键ctrl+shift+/ */ ????????out.println("s="+s+"<br>"); ?????????out.write("\r\n"); ?????out.write("</body>\r\n"); ?????out.write("</html>"); ???} 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); ???????else log(t.getMessage(), t); ?????} ???} finally { ?????_jspxFactory.releasePageContext(_jspx_page_context); ???} ?}}#tomcat#生成的jsp转换问题
原文地址：https://www.cnblogs.com/tnt-33/p/8624536.html