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);
}
}
}
