Spring通过Java配置集成Tomcat的方法

Spring通过Java配置集成Tomcat的方法

添加Tomcat依赖

org.apache

apache-tomcat-9.0.36-src

1.0-SNAPSHOT

首先需要一个tomcat启动类

public class TomcatRun {

private static final int PORT = 8080;

private static final String CONTEXT_PATH =onGHXV "/com/yu";

public static void main(String[] args) {

Tomcat tomcat = new Tomcat();

// 设置监听端口

tomcat.setPort(PORT);

tomcat.getHost().setAppBase(".");

// 这里 Connector 不存在，自动创建一个 Connector，并将 tomcat 的端口赋值给 Connector

tomcat.getConnector();

tomcat.addWebapp(CONTEXT_PATH, new File("src/main/webapp").getAbsolutePath());

try {

tomcat.start();

} catch (LifecycleException e) {

e.printStackTrace();

}

tomcat.getServer().await();

}

}

也可以自己创建一个Connector指定端口

// 手动创建 connector

// Connector connector = new Connector();

// connector.setPort(PORT);

// tomcat.getService().addConnector(connector);

创建Spring配置

public class MyWebApplicationInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {

@Override

protected Class>[] getRootConfigClasses() {

return new Class[]{RootConfig.class};

}

@Override

protected Class>[] getServletConfigClasses() {

return new Class[]{AppConfig.class};

}

@Override

protected String[] getServletMappings() {

return new String[]{"/*"};

}

@Override

protected Filter[] getServletFilters() {

return new Filter[]{

//

new CharacterEncodingFilter(StandardCharsets.UTF_8.name())

};

}

}

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

@HandlesTypes(WebApplicationInitializer.class)

public class SpringServletContainerInitializer implements ServletContainerInitializer {

@Override

public void onStartup(@Nullable Set> webAppInitializerClasses, ServletContext servletContext)

throws ServletException {

List initializers = new LinkedList<>();

if (webAppInitializerClasses != null) {

for (Class> waiClass : webAppInitializerClasses) {

// Be defensive: Some servlet containers provide us with invalid classes,

// no matter what @HandlesTypes says...

if (!waiClass.isInterface() && !Modifier.isAbstract(waiClass.getModifiers()) &&

WebApplicationInitializer.class.isAssignableFrom(waiClass)) {

try {

initializers.add((WebApplicationInitializer)

ReflectionUtils.accessibleConstructor(waiClass).newInstance());

}

catch (Throwable ex) {

throw new ServletException("Failed to instantiate WebApplicationInitializer class", ex);

}

}

}

}

if (initializers.isEmpty()) {

servletContext.log("No Spring WebApplicationInitializer types detected on classpath");

return;

}

servletContext.log(initializers.size() + " Spring WebApplicationInitializers detected on classpath");

AnnotationAwareOrderComparator.sort(initializers);

for (WebApplicationInitializer initializer : initializers) {

// 调用WebApplicationInitializer实现类的onStartup方法

initializer.onStartup(servletContext);

}

}

}

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