Embed Tomcat Java(内嵌tomcat启动简述)

简单记录一下内部tomcat启动

maven pom.xml

<dependencies>
<!-- embed tomcat dependency -->
<dependency>
<groupId>org.apache.tomcat.embed</groupId>
<artifactId>tomcat-embed-core</artifactId>
<version>8.5.28</version>
</dependency>
<dependency>
<groupId>org.apache.tomcat</groupId>
<artifactId>tomcat-jasper</artifactId>
<version>8.5.28</version>
</dependency><!-- spring dependency -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>5.0.4.RELEASE</version>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>5.0.4.RELEASE</version>
<scope>compile</scope>
</dependency>
</dependencies>
<build>
<plugins>
<!-- 添加编译插件 -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.5.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
</plugins>
</build>


tomcat启动类

/**
*
* @author Programming is an art from.
* @Description: TODO
*/
public class TomcatStart { public static int TOMCAT_PORT = 8080;
public static String TOMCAT_HOSTNAME = "127.0.0.1";
public static String WEBAPP_PATH = "src/main";
public static String WEBINF_CLASSES = "/WEB-INF/classes";
public static String CLASS_PATH = "target/classes";
public static String INTERNAL_PATH = "/"; public static void main(String[] args) throws ServletException, LifecycleException {
TomcatStart.run();
} public static void run() throws ServletException, LifecycleException {
Tomcat tomcat = new Tomcat();
tomcat.setPort(TomcatStart.TOMCAT_PORT);
tomcat.setHostname(TomcatStart.TOMCAT_HOSTNAME);
tomcat.setBaseDir("."); // tomcat 信息保存在项目下 /*
* https://www.cnblogs.com/ChenD/p/10061008.html
*/
StandardContext myCtx = (StandardContext) tomcat
.addWebapp("/access", System.getProperty("user.dir") + File.separator + TomcatStart.WEBAPP_PATH);
/*
* true时：相关classes | jar 修改时，会重新加载资源，不过资源消耗很大
* autoDeploy 与这个很相似，tomcat自带的热部署不是特别可靠，效率也不高。生产环境不建议开启。
* 相关文档：
* http://www.blogjava.net/wangxinsh55/archive/2011/05/31/351449.html
*/
myCtx.setReloadable(false);
// 上下文监听器
myCtx.addLifecycleListener(new AprLifecycleListener()); /*String webAppMount = System.getProperty("user.dir") + File.separator + TomcatStart.CLASS_PATH;
WebResourceRoot root = new StandardRoot(myCtx);
root.addPreResources(
new DirResourceSet(root, TomcatStart.WEBINF_CLASSES, webAppMount, TomcatStart.INTERNAL_PATH));*/ // 注册servlet
tomcat.addServlet("/access", "demoServlet", new DemoServlet());
// servlet mapping
myCtx.addServletMappingDecoded("/demo.do", "demoServlet");
tomcat.start();
tomcat.getServer().await();
}}


注意！ contextPath不要设置为 /

否则会报错, 错误信息为以下。

警告: A context path must either be an empty string or start with a '/' and do not end with a '/'. The path [/] does not meet these criteria and has been changed to []
Exception in thread "main" java.lang.NullPointerException
at org.apache.catalina.startup.Tomcat.addServlet(Tomcat.java:341)
at org.apache.catalina.startup.Tomcat.addServlet(Tomcat.java:325)
at cn.learn.config.TomcatStart.run(TomcatStart.java:63)
at cn.learn.config.TomcatStart.main(TomcatStart.java:33)


servlet class

/**
*
* @author Programming is an art from.
* @Description: TODO
*/
public class DemoServlet extends HttpServlet{ /**
*
*/
private static final long serialVersionUID = 1L; @Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
} @Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
resp.getWriter().print("access success!!!");
}}


启动main方法，访问成功喽！

http://127.0.0.1:8080/access/demo.do