#tomcat#生成的jsp转换问题
轉載！
Eclipse中JSP生成的class文件去了哪里？
?
大家都知道，JSP在請求的時候，會先轉化成Servlet（其實就是個java類），然后生成class文件，再提供服務。
那么生成的java、class文件在哪呢？Eclipse中根本找不到呀！
首先應該了解的是Tomcat在Eclipse的映射關系，參考前一篇博文所述：Tomcat的服務器目錄配置
可以了解到，Tomcat在Eclipse中提供了三種位置配置選項：
1 Use workspace metadata
2 Use Tomcat installation
3 Use custom location
分別對應三種情況說一下，注意要把Server中發布的目錄全部刪除，然后clean后才能修改該配置項。
如果你在Eclipse中雙擊Server配置選項，在Server Location中分別選了如下的選項：
如果Server Locations選擇了第一項Use workspace metadata
選了上面這項，你的服務器目錄和發布目錄將會如下：
服務器目錄，即生成的字節碼和java文件所在的目錄。它在你的eclipse的工作目錄中，比如我的工作目錄是在F://workspace，那么在該目錄下就可以看到這個.metadata目錄了。
參考上面的配置目錄F:\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0
這就是Tomcat映射的目錄，在這個目錄中有一個work目錄和一個wtpwebapps目錄
work目錄中順著：work\Catalina\localhost\項目名字\org\apache\jsp?就可以找到你的項目對應的java文件和class文件（注意要訪問jsp后才會出現！）
wtpwebapps目錄則存放對應的部署資源文件
如果選擇的是第二項，Use Tomcat installation
如果勾選的use tomcat installation，那么你的tomcat目錄將被選定為tomcat所安裝的目錄。
還是推薦選擇這個吧，畢竟好找一點。
如果勾選第三項，Use custom location
目錄的結構與上面的類似，上面這兩個都是不可以修改的，要么是workspace所在的目錄，要么是tomcat的目錄。
選擇該項，可以自定義生成的空間。
另外說一點，JSP的生命周期
這是老生常談的問題了，用戶把工程部署到tomcat中，然后啟動tomcat！此時就可以訪問jsp了、
1 第一次訪問JSP，會驗證一下是否第一次訪問，然后把JSP轉化成java(Servlet),再編譯成class文件。
2 生成的class文件中會自動生成幾個方法：jspInit()、jspDestroy()、jspService().Tomcat僅僅在第一次請求時，調用jspInit方法，然后調用jspService進行處理。
3 之后的每個請求，都會分配一個線程調用jspService方法。
4 如果頁面被銷毀或者關閉，都會調用jspDestroy
由于該文件是常駐內存的，又是多線程調用，所以訪問的效率和速度都會很快。
按照前面所述的方法，就可以看到生成的文件結構了。
按照前面所述的方法，就可以看到生成的文件結構了。
為了展示，這里給出一個樣例的JSP
<%@ page language="java" import="java.util.*,java.io.*" contentType="text/html; charset=utf-8"%>
<%--
language 腳本使用的語言
import 加載類文件
contentType 編碼方式
--%>
<!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>
<!-- 客戶端可見 -->
<%-- 客戶端不可見 --%>
<%!
String s = "xingoo";//聲明變量
int add(int a,int b){//聲明函數
return a+b;
}
%>
s=<%=s %><br> <%--表達式不以分號結束 --%>
1+2=<%=add(1,2) %><br>
<%
//單行注釋 ————————————————快捷鍵ctrl+/
/* 多行注釋 ____________快捷鍵ctrl+shift+/ */
out.println("s="+s+"<br>");
%>
</body>
</html>
里面含有一些注釋，變量聲明和打印輸出等等。
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";//聲明變量 int add(int a,int b){//聲明函數 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<!-- 客戶端可見 -->\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"); //單行注釋 ————————————————快捷鍵ctrl+/ /* 多行注釋 ____________快捷鍵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";//聲明變量
int add(int a,int b){//聲明函數
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<!-- 客戶端可見 -->\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");
//單行注釋 ————————————————快捷鍵ctrl+/
/* 多行注釋 ____________快捷鍵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);
}
}
}
聲明注釋，都可以很詳細的看到。
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";//聲明變量 int add(int a,int b){//聲明函數 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<!-- 客戶端可見 -->\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"); //單行注釋 ————————————————快捷鍵ctrl+/ /* 多行注釋 ____________快捷鍵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); } } }轉載于:https://www.cnblogs.com/tnt-33/p/8624536.html
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