本文所用到的环境：
- IntelliJ IDEA
- Apache Maven 3.3.9
- jdk1.8
1. 查看Tomcat版本
$TOMCAT_HOMEinversion.bat
D:Program_Filesapache-tomcat-9.0.19in>version.bat
Using CATALINA_BASE: "D:Program_Filesapache-tomcat-9.0.19"
Using CATALINA_HOME: "D:Program_Filesapache-tomcat-9.0.19"
Using CATALINA_TMPDIR: "D:Program_Filesapache-tomcat-9.0.19 emp"
Using JRE_HOME: "D:Program FilesJavajdk1.8.0_77"
Using CLASSPATH: "D:Program_Filesapache-tomcat-9.0.19inootstrap.jar;D:Program_Filesapache-tomcat-9.0.19in omcat-juli.jar"
Server version: Apache Tomcat/9.0.19
Server built: Apr 12 2019 14:22:48 UTC
Server number: 9.0.19.0
OS Name: Windows 10
OS Version: 10.0
Architecture: amd64
JVM Version: 1.8.0_77-b03
JVM Vendor: Oracle Corporation
D:Program_Filesapache-tomcat-9.0.19in>
这里使用的是JDK1.8，如果不是JDK1.8，则需要查看tomcat的兼容，选择适合自己的版本
2. 下载源码
根据自己的Tomcat版本，下载对应的源码
选择对应版本的tomcat，这里我使用的tomcat9，选择Archives
下载完成后解压，apache-tomcat-9.0.19-src
3. 创建项目结构
-
在D盘创建“D: omcat9.0.19”文件夹，然后将解压后的文件拷贝到该目录中，同时创建“catalina-home”目录
-
拷贝“apache-tomcat-9.0.19-srcconf”，到“catalina-home”目录下
-
创建“D: omcat9.0.19pom.xml”文件
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>org.apache.tomcat</groupId> <artifactId>Tomcat9.0.19</artifactId> <name>Tomcat 9.0 Study</name> <version>1.0</version> <packaging>pom</packaging> <modules> <module>apache-tomcat-9.0.19-src</module> </modules> </project> -
创建“D: omcat9.0.19apache-tomcat-9.0.19-srcpom.xml”文件
<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>org.apache.tomcat</groupId> <artifactId>Tomcat9.0</artifactId> <name>Tomcat9</name> <version>9.0</version> <build> <finalName>Tomcat9</finalName> <sourceDirectory>java</sourceDirectory> <resources> <resource> <directory>java</directory> </resource> </resources> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>2.3</version> <configuration> <encoding>UTF-8</encoding> <source>1.8</source> <target>1.8</target> </configuration> </plugin> </plugins> </build> <dependencies> <dependency> <groupId>org.apache.ant</groupId> <artifactId>ant</artifactId> <version>1.9.5</version> </dependency> <dependency> <groupId>org.apache.ant</groupId> <artifactId>ant-apache-log4j</artifactId> <version>1.9.5</version> </dependency> <dependency> <groupId>org.apache.ant</groupId> <artifactId>ant-commons-logging</artifactId> <version>1.9.5</version> </dependency> <dependency> <groupId>javax.xml.rpc</groupId> <artifactId>javax.xml.rpc-api</artifactId> <version>1.1</version> </dependency> <dependency> <groupId>wsdl4j</groupId> <artifactId>wsdl4j</artifactId> <version>1.6.2</version> </dependency> <dependency> <groupId>org.eclipse.jdt.core.compiler</groupId> <artifactId>ecj</artifactId> <version>4.4</version> </dependency> </dependencies> </project>
最终的目录结构为：
Administrator@git MINGW64 /d/tomcat9.0.19
$ ls -l total 6
drwxr-xr-x 1 Administrator 197121 0 3月 30 17:50 apache-tomcat-9.0.19-src
drwxr-xr-x 1 Administrator 197121 0 3月 30 17:41 catalina-home
-rw-r--r-- 1 Administrator 197121 533 3月 30 17:27 pom.xml
Administrator@git MINGW64 /d/tomcat9.0.19
$ ls -l catalina-home/ total 8
drwxr-xr-x 1 Administrator 197121 0 3月 30 17:38 conf
4. 将该项目导入到IDEA中
5. 编译
由于这里使用是JDK1.8，所以需要注释掉这些代码，否则容易报错：
编译：
6. 运行
1）创建Application
vm option 配置：
-Dfile.encoding=UTF-8 -Dcatalina.home=catalina-home -Dcatalina.base=catalina-home -Djava.endorsed.dirs=catalina-home/endorsed -Djava.io.tmpdir=catalina-home/temp -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djava.util.logging.config.file=catalina-home/conf/logging.properties
在Bootstrap的main方法当中加入测试代码：
System.out.println("======================Tomcat Study======================");
下面是部分启动日志：
======================Tomcat Study======================
30-Mar-2020 17:38:32.009 警告 [main] org.apache.catalina.startup.ClassLoaderFactory.validateFile Problem with directory [D: omcat9.0.19catalina-homelib], exists: [false], isDirectory: [false], canRead: [false]
30-Mar-2020 17:38:32.017 警告 [main] org.apache.catalina.startup.ClassLoaderFactory.validateFile Problem with directory [D: omcat9.0.19catalina-homelib], exists: [false], isDirectory: [false], canRead: [false]
30-Mar-2020 17:38:32.017 警告 [main] org.apache.catalina.startup.ClassLoaderFactory.validateFile Problem with directory [D: omcat9.0.19catalina-homelib], exists: [false], isDirectory: [false], canRead: [false]
30-Mar-2020 17:38:32.017 警告 [main] org.apache.catalina.startup.ClassLoaderFactory.validateFile Problem with directory [D: omcat9.0.19catalina-homelib], exists: [false], isDirectory: [false], canRead: [false]
但是启动日志会有乱码，解决方法：
为何会有乱码：
原因：一般是中文编码不匹配导致；经跟踪，发现是ResourceBundle读取orgapachecatalinastartupLocalStrings_zh_CN.properties文件时没有用utf8解码导致；
解决：修改org.apache.tomcat.util.res.StringManager类中的getString函数；
由if (bundle != null) { str = bundle.getString(key); }改为
if (bundle != null) { str = new String(bundle.getString(key).getBytes(“ISO-8859-1”), “UTF-8”); }再次运行，一切正常
2）实验
- 在“catalina-homewebapps”目录中创建“demoindex.html”文件：
<html>
<head><title>Tomcat9.0.19_Test</title></head>
<body>
<h1>Hello World!!!</h1>
</body>
</html>
访问： http://127.0.0.1:8080/demo/
- 在“catalina-homewebapps”目录中创建“demoindex.jsp”文件：
<%@ page contentType="text/html;charset=utf-8" pageEncoding="utf-8"%>
<html>
<head><title>Test-title</title></head>
<body>
<%
request.setCharacterEncoding("utf-8");
String method = request.getMethod() ; // 取得提交方式
String ip = request.getRemoteAddr() ; // 取得客户端的IP地址
String path = request.getServletPath() ; // 取得访问路径
String contextPath1= request.getContextPath() ; // 取得上下文资源名称
String contextPath2 = getServletContext().getContextPath() ;// 取得上下文资源名称
String realPath=getServletContext().getRealPath("/");//取得虚拟目录所对应的真实路径
%>
<h3>请求方式：<%=method%></h3>
<h3>IP地址：<%=ip%></h3>
<h3>访问路径：<%=path%></h3>
<h3>上下文名称1：<%=contextPath1%></h3>
<h3>上下文名称2：<%=contextPath2%></h3>
<h3>真实路径：<%=realPath%></h3>
</body>
</html>
访问： http://127.0.0.1:8080/demo/index.jsp
调试程序
index.jsp在被编译后会生成“index_jsp.java”和“index_jsp.class”文件，位置如下：
Administrator@git MINGW64 /d/tomcat9.0.19/catalina-home/work/Catalina/localhost/demo/org/apache/jsp
$ pwd
/d/tomcat9.0.19/catalina-home/work/Catalina/localhost/demo/org/apache/jsp
Administrator@git MINGW64 /d/tomcat9.0.19/catalina-home/work/Catalina/localhost/demo/org/apache/jsp
$ ls index_jsp.java
index_jsp.java
Administrator@git MINGW64 /d/tomcat9.0.19/catalina-home/work/Catalina/localhost/demo/org/apache/jsp
$ ls index_jsp.class
index_jsp.class
下面是“index_jsp.java”文件的内容：
/*
* Generated by the Jasper component of Apache Tomcat
* Version: Apache Tomcat/9.0.x-dev
* Generated at: 2020-03-30 10:23:23 UTC
* Note: The last modified time of this file was set to
* the last modified time of the source file after
* generation to assist with modification tracking.
*/
package org.apache.jsp;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.*;
public final class index_jsp extends org.apache.jasper.runtime.HttpJspBase
implements org.apache.jasper.runtime.JspSourceDependent,
org.apache.jasper.runtime.JspSourceImports {
private static final javax.servlet.jsp.JspFactory _jspxFactory =
javax.servlet.jsp.JspFactory.getDefaultFactory();
private static java.util.Map<java.lang.String,java.lang.Long> _jspx_dependants;
private static final java.util.Set<java.lang.String> _jspx_imports_packages;
private static final java.util.Set<java.lang.String> _jspx_imports_classes;
static {
_jspx_imports_packages = new java.util.HashSet<>();
_jspx_imports_packages.add("javax.servlet");
_jspx_imports_packages.add("javax.servlet.http");
_jspx_imports_packages.add("javax.servlet.jsp");
_jspx_imports_classes = null;
}
private volatile javax.el.ExpressionFactory _el_expressionfactory;
private volatile org.apache.tomcat.InstanceManager _jsp_instancemanager;
public java.util.Map<java.lang.String,java.lang.Long> getDependants() {
return _jspx_dependants;
}
public java.util.Set<java.lang.String> getPackageImports() {
return _jspx_imports_packages;
}
public java.util.Set<java.lang.String> getClassImports() {
return _jspx_imports_classes;
}
public javax.el.ExpressionFactory _jsp_getExpressionFactory() {
if (_el_expressionfactory == null) {
synchronized (this) {
if (_el_expressionfactory == null) {
_el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory();
}
}
}
return _el_expressionfactory;
}
public org.apache.tomcat.InstanceManager _jsp_getInstanceManager() {
if (_jsp_instancemanager == null) {
synchronized (this) {
if (_jsp_instancemanager == null) {
_jsp_instancemanager = org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(getServletConfig());
}
}
}
return _jsp_instancemanager;
}
public void _jspInit() {
}
public void _jspDestroy() {
}
public void _jspService(final javax.servlet.http.HttpServletRequest request, final javax.servlet.http.HttpServletResponse response)
throws java.io.IOException, javax.servlet.ServletException {
if (!javax.servlet.DispatcherType.ERROR.equals(request.getDispatcherType())) {
final java.lang.String _jspx_method = request.getMethod();
if ("OPTIONS".equals(_jspx_method)) {
response.setHeader("Allow","GET, HEAD, POST, OPTIONS");
return;
}
if (!"GET".equals(_jspx_method) && !"POST".equals(_jspx_method) && !"HEAD".equals(_jspx_method)) {
response.setHeader("Allow","GET, HEAD, POST, OPTIONS");
response.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, "JSP åªå
许 GETãPOST æ HEADãJasper è¿å
许 OPTIONS");
return;
}
}
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("<html>
");
out.write("<head><title>Test-title</title></head>
");
out.write("<body>
");
request.setCharacterEncoding("utf-8");
String method = request.getMethod() ; // 取得提交方式
String ip = request.getRemoteAddr() ; // 取得客户端的IP地址
String path = request.getServletPath() ; // 取得访问路径
String contextPath1= request.getContextPath() ; // 取得上下文资源名称
String contextPath2 = getServletContext().getContextPath() ;// 取得上下文资源名称
String realPath=getServletContext().getRealPath("/");//取得虚拟目录所对应的真实路径
out.write("
");
out.write("<h3>请求方式：");
out.print(method);
out.write("</h3>
");
out.write("<h3>IP地址：");
out.print(ip);
out.write("</h3>
");
out.write("<h3>访问路径：");
out.print(path);
out.write("</h3>
");
out.write("<h3>上下文名称1：");
out.print(contextPath1);
out.write("</h3>
");
out.write("<h3>上下文名称2：");
out.print(contextPath2);
out.write("</h3>
");
out.write("<h3>真实路径：");
out.print(realPath);
out.write("</h3>
");
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);
}
}
}
这些是JSP的内置对象，另外还有request和response内置对象，在方法参数上
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;
下面是它们的赋值操作：
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;
能够看到它们都是通过pageContext的对应方法来进行赋值的。
实际上我们也可以在界面上将这些内置对象打印出来：
test.jsp
<%@ page contentType="text/html" pageEncoding="GBK"%>
<%@ page import="java.util.*"%> <!-- 导入java.util包 -->
<html>
<head><title>PageScope</title></head>
<body>
<h4>request：<%=request%></h4>
<h4>session：<%=session%></h4>
<h4>application：<%=application%></h4>
<h4>response：<%=response%></h4>
<h4>out：<%=out%></h4>
<h4>config：<%=config%></h4>
<h4>page：<%=page%></h4>
<h4>pageContext：<%=pageContext%></h4>
<h4>getException：<%=pageContext.getException()%></h4>
<h4>getPage：<%=(pageContext.getPage()==page)%></h4>
<h4>getRequest：<%=(pageContext.getRequest()==request)%></h4>
<h4>getResponse：<%=(pageContext.getResponse()==response)%></h4>
<h4>getSession：<%=(pageContext.getSession()==session)%></h4>
<h4>getServletConfig：<%=(pageContext.getServletConfig()==config) %></h4>
<h4>getServletContext：<%=(pageContext.getServletContext()==application)%></h4>
</body>
</html>
运行结果：
再回到调试的问题上来，想要调试“index_jsp.java”，需要创建“org/apache/jsp”文件夹，然后将该文件移动到该文件夹下，打上断点就可以开始调试了：
3）注意
默认情况下解析JSP会报错
- 现象：
Type Exception Report
Message java.lang.NullPointerException
Description The server encountered an unexpected condition that prevented it from fulfilling the request.
Exception
org.apache.jasper.JasperException: java.lang.NullPointerException
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:638)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:514)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
Root Cause
java.lang.NullPointerException
org.apache.jsp.index_jsp._jspService(index_jsp.java:165)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:476)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
Note The full stack trace of the root cause is available in the server logs.
-
问题分析和解决方法
原因是我们直接启动org.apache.catalina.startup.Bootstrap的时候没有加载org.apache.jasper.servlet.JasperInitializer，从而无法编译JSP。解决办法是在tomcat的源码org.apache.catalina.startup.ContextConfig中手动将JSP解析器初始化：
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版权声明：本文为CSDN博主「yehong1225」的原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/yekong1225/article/details/81000446 -
再次测试正常
4）切换到Tomcat主目录，将VM options修改为如下配置即可
-Dcatalina.home=apache-tomcat-9.0.19-src -Dcatalina.base=apache-tomcat-9.0.19-src
-Djava.endorsed.dirs=apache-tomcat-9.0.19-src/endorsed -Djava.io.tmpdir=apache-tomcat-9.0.19-src/temp
-Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager
-Djava.util.logging.config.file=apache-tomcat-9.0.19-src/conf/logging.properties
参考链接：