内嵌tomcat最简单用法
maven项目引入内嵌tomcat依赖
<dependency> <groupId>org.apache.tomcat.embed</groupId> <artifactId>tomcat-embed-core</artifactId> <version>8.5.37</version> </dependency>
编写如下main方法
1 package com;
2
3 import org.apache.catalina.Context;
4 import org.apache.catalina.LifecycleException;
5 import org.apache.catalina.startup.Tomcat;
6 import org.apache.tomcat.util.descriptor.web.FilterDef;
7 import org.apache.tomcat.util.descriptor.web.FilterMap;
8 import org.springframework.web.filter.OncePerRequestFilter;
9
10 import javax.servlet.Filter;
11 import javax.servlet.FilterChain;
12 import javax.servlet.ServletException;
13 import javax.servlet.http.HttpServlet;
14 import javax.servlet.http.HttpServletRequest;
15 import javax.servlet.http.HttpServletResponse;
16 import java.io.IOException;
17 import java.nio.charset.Charset;
18
19 /**
20 * @author allen
21 * @date 2019-01-22 13:20
22 */
23 public class TomcatWebServer {
24 public static void main(String[] args) {
25 Tomcat tomcat = new Tomcat();
26 HttpServlet httpServlet = new HttpServlet() {
27 @Override
28 protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
29 resp.getWriter().write("hello, i'm embed tomcat");
30 }
31
32 @Override
33 protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {
34 doGet(req, resp);
35 }
36 };
37 tomcat.setHostname("localhost");
38 tomcat.setPort(8080);
39 final Context context = tomcat.addContext("/embed-tomcat", null);
40 Tomcat.addServlet(context, "dispatch", httpServlet);
41 context.addServletMappingDecoded("/dispatch", "dispatch");
42 Filter filter = new OncePerRequestFilter() {
43 @Override
44 protected void doFilterInternal(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, FilterChain filterChain) throws ServletException, IOException {
45 System.out.println("filter do something");
46 filterChain.doFilter(httpServletRequest, httpServletResponse);
47 }
48 };
49 FilterDef filterDef = new FilterDef();
50 filterDef.setFilter(filter);
51 filterDef.setFilterName("myFilter");
52 filterDef.addInitParameter("userName", "Allen");
53
54 FilterMap filterMap = new FilterMap();
55 filterMap.addURLPatternDecoded("/*");
56 filterMap.addServletName("*");
57 filterMap.setFilterName("myFilter");
58 filterMap.setCharset(Charset.forName("UTF-8"));
59
60 context.addFilterDef(filterDef);
61 context.addFilterMap(filterMap);
62 try {
63 tomcat.init();
64 tomcat.start();
65 tomcat.getServer().await();
66 } catch (LifecycleException e) {
67 e.printStackTrace();
68 }
69 }
70 }
注意其中OncePerRequestFilter是spring提供的对filter接口的实现类，没有引入spring依赖的可自行改用其他实现类。
运行main方法，一个最简单的tomcat实例已经运行起来。浏览器打开http://localhost:8080/embed-tomcat/dispatch，页面可以看到输出内容，控制台也打印了过滤器执行的内容。
springboot默认就是使用tomcat作为内嵌容器的，基本原理通上述代码，只不过spring做了更深层次的封装，结合其ioc容器，可以实现只要往ioc容器中注入servlet、filter接口的实现类，spring的适配器可自动完成配置。
