Spring通过Java配置集成Tomcat的方法

添加Tomcat依赖

1. <!-- 自己编译的版本-->
2. <dependency>
3. <groupId>org.apache</groupId>
4. <artifactId>apache-tomcat-9.0.36-src</artifactId>
5. <version>1.0-SNAPSHOT</version>
6. </dependency>

首先需要一个tomcat启动类

1. public class TomcatRun {
2.  
3. private static final int PORT = 8080;
4. private static final String CONTEXT_PATH = "/com/yu";
5.  
6. public static void main(String[] args) {
7. Tomcat tomcat = new Tomcat();
8. // 设置监听端口
9. tomcat.setPort(PORT);
10. tomcat.getHost().setAppBase(".");
11. // 这里 Connector 不存在，自动创建一个 Connector，并将 tomcat 的端口赋值给 Connector
12. tomcat.getConnector();
13. tomcat.addWebapp(CONTEXT_PATH, new File("src/main/webapp").getAbsolutePath());
14. try {
15. tomcat.start();
16. } catch (LifecycleException e) {
17. e.printStackTrace();
18. }
19. tomcat.getServer().await();
20. }
21. }

也可以自己创建一个Connector指定端口

1. // 手动创建 connector
2. // Connector connector = new Connector();
3. // connector.setPort(PORT);
4. // tomcat.getService().addConnector(connector);

创建Spring配置

1. public class MyWebApplicationInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
2. @Override
3. protected Class<?>[] getRootConfigClasses() {
4. return new Class[]{RootConfig.class};
5. }
6.  
7. @Override
8. protected Class<?>[] getServletConfigClasses() {
9. return new Class[]{AppConfig.class};
10. }
11.  
12. @Override
13. protected String[] getServletMappings() {
14. return new String[]{"/*"};
15. }
16.  
17. @Override
18. protected Filter[] getServletFilters() {
19. return new Filter[]{
20. //
21. new CharacterEncodingFilter(StandardCharsets.UTF_8.name())
22. };
23. }
24. }

这里就结束了。。。

---

问题来了Tomcat是怎么启动Sping的?

 

实现了Servlet3.0的容器（例如Tomcat）会扫描classpath*下面的META-INF/services/javax.servlet.ServletContainerInitializer文件，里面指定ServletContainerInitializer的实现，另外还有一个注解HandlesTypes表达对某个类感兴趣，在调用onStartup方法时会将HandlesTypes指定接口的实现类传递进来。

例如：Spring中的ServletContainerInitializer实现类SpringServletContainerInitializer会调用WebApplicationInitializer的onStartup方法，也就是上面定义的MyWebApplicationInitializer父类的onStartup，这里就会相继完成AnnotationConfigWebApplicationContext和DispatcherServlet的初始化

1. @HandlesTypes(WebApplicationInitializer.class)
2. public class SpringServletContainerInitializer implements ServletContainerInitializer {
3.  
4. @Override
5. public void onStartup(@Nullable Set<Class<?>> webAppInitializerClasses, ServletContext servletContext)
6. throws ServletException {
7.  
8. List<WebApplicationInitializer> initializers = new LinkedList<>();
9.  
10. if (webAppInitializerClasses != null) {
11. for (Class<?> waiClass : webAppInitializerClasses) {
12. // Be defensive: Some servlet containers provide us with invalid classes,
13. // no matter what @HandlesTypes says...
14. if (!waiClass.isInterface() && !Modifier.isAbstract(waiClass.getModifiers()) &&
15. WebApplicationInitializer.class.isAssignableFrom(waiClass)) {
16. try {
17. initializers.add((WebApplicationInitializer)
18. ReflectionUtils.accessibleConstructor(waiClass).newInstance());
19. }
20. catch (Throwable ex) {
21. throw new ServletException("Failed to instantiate WebApplicationInitializer class", ex);
22. }
23. }
24. }
25. }
26.  
27. if (initializers.isEmpty()) {
28. servletContext.log("No Spring WebApplicationInitializer types detected on classpath");
29. return;
30. }
31.  
32. servletContext.log(initializers.size() + " Spring WebApplicationInitializers detected on classpath");
33. AnnotationAwareOrderComparator.sort(initializers);
34. for (WebApplicationInitializer initializer : initializers) {
35. // 调用WebApplicationInitializer实现类的onStartup方法
36. initializer.onStartup(servletContext);
37. }
38. }
39.  
40. }

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原文链接：https://blog.csdn.net/weixin_45387444/article/details/115682664