一、下載tomcat源碼

https://github.com/apache/tomcat/tree/8.5.x

二、建立pom

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <project xmlns="http://maven.apache.org/POM/4.0.0"
 3          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 5 
 6     <modelVersion>4.0.0</modelVersion>
 7     <groupId>org.apache.tomcat</groupId>
 8     <artifactId>Tomcat8.5</artifactId>
 9     <name>Tomcat8.0</name>
10     <version>8.0</version>
11 
12     <build>
13         <finalName>Tomcat8.5</finalName>
14         <sourceDirectory>java</sourceDirectory>
15         <testSourceDirectory>test</testSourceDirectory>
16         <resources>
17             <resource>
18                 <directory>java</directory>
19             </resource>
20         </resources>
21         <testResources>
22             <testResource>
23                 <directory>test</directory>
24             </testResource>
25         </testResources>
26         <plugins>
27             <plugin>
28                 <groupId>org.apache.maven.plugins</groupId>
29                 <artifactId>maven-compiler-plugin</artifactId>
30                 <version>2.3</version>
31                 <configuration>
32                     <encoding>UTF-8</encoding>
33                     <source>1.8</source>
34                     <target>1.8</target>
35                 </configuration>
36             </plugin>
37         </plugins>
38     </build>
39 
40     <dependencies>
41         <dependency>
42             <groupId>junit</groupId>
43             <artifactId>junit</artifactId>
44             <version>4.12</version>
45             <scope>test</scope>
46         </dependency>
47         <dependency>
48             <groupId>org.easymock</groupId>
49             <artifactId>easymock</artifactId>
50             <version>3.4</version>
51         </dependency>
52         <dependency>
53             <groupId>ant</groupId>
54             <artifactId>ant</artifactId>
55             <version>1.7.0</version>
56         </dependency>
57         <dependency>
58             <groupId>wsdl4j</groupId>
59             <artifactId>wsdl4j</artifactId>
60             <version>1.6.2</version>
61         </dependency>
62         <dependency>
63             <groupId>javax.xml</groupId>
64             <artifactId>jaxrpc</artifactId>
65             <version>1.1</version>
66         </dependency>
67         <dependency>
68             <groupId>org.eclipse.jdt.core.compiler</groupId>
69             <artifactId>ecj</artifactId>
70             <version>4.5.1</version>
71         </dependency>
72 
73     </dependencies>
74 </project>

編譯可能有個測試類過不了。刪除即可。

三、新建catalina-home目錄

• 把webapp文件夾和conf文件夾copy到Catalina-home目錄
• 新建空文件夾temp、log、lib

四，設置啟動參數

-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

• main class設置為 org.apache.catalina.startup.Bootstrap
• vm option複製上面的參數主要是設置Catalina的啟動目錄

 五、啟動

 至此，tomcat已經成功啟動。

六、訪問tomcat

發現有NPE

解決：在Bootstrap中啟動jasper，修改代碼，在ContextConfig中加入如下代碼

context.addServletContainerInitializer(new JasperInitializer(), null);

啟動成功。