先建一个标准的 maven web 项目


tomcat.embed.version 8.5.0

引入依赖




<dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-core</artifactId>
            <version>${tomcat.embed.version}</version>
        </dependency>

        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
            <version>${tomcat.embed.version}</version>
            <!--<scope>provided</scope>-->
        </dependency>
        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-logging-juli</artifactId>
            <version>${tomcat.embed.version}</version>
        </dependency>
        
 
<dependency>
    <groupId>javax.servlet</groupId>
     <artifactId>javax.servlet-api</artifactId>
     <version>3.1.0</version>
     <scope>provided</scope>
</dependency>

<dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.8</version>
        </dependency>
 



先放一个最简单jsp页面 ， 也可以使用 servlet
src/main/webapp/index.jsp

写一个java类用于启动 tomcat 

dyyx/TomcatServerStart.java




package dyyx;

import java.net.URL;
import java.util.Date;

import org.apache.catalina.startup.Tomcat;
import org.apache.commons.lang3.StringUtils;

public class TomcatServerStart {
	
	private static int port = 8080;
	// /
	// A context path must either be an empty string or start with a '/' and do not end with a '/'
    private static String contextPath = "";

	public static void main(final String[] args) throws Exception{
		System.out.println("TomcatServerStart,"+new Date());
		start();
	}
	
	public static void start() throws Exception {
        Tomcat tomcat = new Tomcat();
        String resource = "dyyx/TomcatServerStart.class";
        URL url = TomcatServerStart.class.getClassLoader().getResource(resource);
        System.out.println(url);
        
        String path = url.getPath();
        System.out.println(path);
        
        String classesPath = "target/classes/";       
        String base = StringUtils.substringBefore(path, classesPath);
        
        // String baseDir = "/Users/dugang/fun/hellocode/project/tomcat-embed/target/classes/";
        // String webAppDir = "/Users/dugang/fun/hellocode/project/tomcat-embed/src/main/webapp/";
        
        String webAppDir =  base + "src/main/webapp/";
        String baseDir = base + classesPath;
        
        System.out.println("baseDir="+baseDir);
        System.out.println("webAppDir="+webAppDir);
  
        tomcat.setBaseDir(baseDir);
        tomcat.setPort(port);

        tomcat.addWebapp(contextPath, webAppDir);
        // tomcat.enableNaming();
        tomcat.start();
        tomcat.getServer().await();
    }

}


使用嵌入式启动，可以愉快的跟踪调试， 譬如 tomcat 的 启动过程