Spring WebFlux安装的支持类。
AbstractAnnotationConfigDispatcherHandlerInitializer
getConfigClasses（）需要具体实现类。更多的模板和定制方法由AbstractDispatcherHandlerInitializer提供。
public abstract class AbstractAnnotationConfigDispatcherHandlerInitializer
extends AbstractDispatcherHandlerInitializer {
/**
* 创建要提供给DispatcherHandler的应用程序上下文。
* 返回的上下文被委托给Spring的DispatcherHandler.DispatcherHandler（ApplicationContext）。因此，它通常包含控制
* 器，视图解析器和其他Web相关的bean。
* 该实现创建一个AnnotationConfigApplicationContext，为其提供由getConfigClasses（）返回的带注释的类。
*/
@Override
protected ApplicationContext createApplicationContext() {
AnnotationConfigApplicationContext servletAppContext = new AnnotationConfigApplicationContext();
Class<?>[] configClasses = getConfigClasses();
if (!ObjectUtils.isEmpty(configClasses)) {
servletAppContext.register(configClasses);
}
return servletAppContext;
}
/**
* 为应用程序上下文指定@Configuration或者@Component类。
* 返回dispatcher servlet应用程序上下文的配置类
*/
protected abstract Class<?>[] getConfigClasses();
}
AbstractDispatcherHandlerInitializer
WebApplicationInitializer实现的基类，在Servlet上下文中注册一个DispatcherHandler，并将其包装在一个ServletHttpHandlerAdapter中。
大多数应用程序应该考虑扩展Spring Java配置，AbstractAnnotationConfigDispatcherHandlerInitializer子类。
public abstract class AbstractDispatcherHandlerInitializer implements WebApplicationInitializer {
/**
* 默认的servlet名字. 可以通过覆盖{@link #getServletName}来自定义.
*/
public static final String DEFAULT_SERVLET_NAME = "dispatcher-handler";
/**
* 默认的servlet映射。. 可以通过覆盖{@link #getServletMapping()}.来自定义
*/
public static final String DEFAULT_SERVLET_MAPPING = "/";
//配置给定的ServletContext（servlets, filters, listeners context-params and attributes ）来初始化此Web应用程序
@Override
public void onStartup(ServletContext servletContext) throws ServletException {
registerDispatcherHandler(servletContext);
}
/**
* 针对给定的servlet上下文注册一个DispatcherHandler。
*此方法将创建一个DispatcherHandler，并使用从createApplicationContext（）返回的应用程序上下文对其进行初始化。创
* 建的处理程序将被包装在一个ServletHttpHandlerAdapter servlet中，其名称由getServletName（）返回，将其映射到从
*getServletMapping（）返回的模式。
*进一步的自定义可以通过覆盖customizeRegistration（ServletRegistration.Dynamic）或
* createDispatcherHandler（ApplicationContext）来实现。
*/
protected void registerDispatcherHandler(ServletContext servletContext) {
String servletName = getServletName();
Assert.hasLength(servletName, "getServletName() must not return empty or null");
ApplicationContext applicationContext = createApplicationContext();
Assert.notNull(applicationContext,
"createApplicationContext() did not return an application " +
"context for servlet [" + servletName + "]");
refreshApplicationContext(applicationContext);
registerCloseListener(servletContext, applicationContext);
WebHandler dispatcherHandler = createDispatcherHandler(applicationContext);
Assert.notNull(dispatcherHandler,
"createDispatcherHandler() did not return a WebHandler for servlet [" + servletName + "]");
ServletHttpHandlerAdapter handlerAdapter = createHandlerAdapter(dispatcherHandler);
Assert.notNull(handlerAdapter,
"createHttpHandler() did not return a ServletHttpHandlerAdapter for servlet [" + servletName + "]");
ServletRegistration.Dynamic registration = servletContext.addServlet(servletName, handlerAdapter);
Assert.notNull(registration,
"Failed to register servlet with name '" + servletName + "'." +
"Check if there is another servlet registered under the same name.");
registration.setLoadOnStartup(1);
registration.addMapping(getServletMapping());
registration.setAsyncSupported(true);
customizeRegistration(registration);
}
/**
* Return the name under which the {@link ServletHttpHandlerAdapter} will be registered.
* Defaults to {@link #DEFAULT_SERVLET_NAME}.
* @see #registerDispatcherHandler(ServletContext)
*/
protected String getServletName() {
return DEFAULT_SERVLET_NAME;
}
/**
* 创建要提供给DispatcherHandler的应用程序上下文。
* 返回的上下文被委托给Spring的DispatcherHandler.DispatcherHandler（ApplicationContext）。因此，它通常包含控制
* 器，视图解析器和其他Web相关的bean。
*/
protected abstract ApplicationContext createApplicationContext();
/**
* 如有必要，刷新给定的应用程序上下文。
*/
protected void refreshApplicationContext(ApplicationContext context) {
if (context instanceof ConfigurableApplicationContext) {
ConfigurableApplicationContext cac = (ConfigurableApplicationContext) context;
if (!cac.isActive()) {
cac.refresh();
}
}
}
/**
* 使用指定的ApplicationContext创建DispatcherHandler（或其他类型的WebHandler派生调度程序）。
*/
protected WebHandler createDispatcherHandler(ApplicationContext applicationContext) {
return new DispatcherHandler(applicationContext);
}
/**
*创建一个ServletHttpHandlerAdapter。 默认实现返回一个ServletHttpHandlerAdapter和提供的webHandler。
*/
protected ServletHttpHandlerAdapter createHandlerAdapter(WebHandler webHandler) {
HttpHandler httpHandler = new HttpWebHandlerAdapter(webHandler);
return new ServletHttpHandlerAdapter(httpHandler);
}
/**
* Specify the servlet mapping for the {@code ServletHttpHandlerAdapter}.
* <p>Default implementation returns {@code /}.
* @see #registerDispatcherHandler(ServletContext)
*/
protected String getServletMapping() {
return DEFAULT_SERVLET_MAPPING;
}
/**
*一旦registerDispatcherHandler（ServletContext）完成，可以选择执行进一步的注册自定义配置定制。
*
*/
protected void customizeRegistration(ServletRegistration.Dynamic registration) {
}
/**
* Register a {@link ServletContextListener} that closes the given application context
*/
protected void registerCloseListener(ServletContext servletContext, ApplicationContext applicationContext) {
if (applicationContext instanceof ConfigurableApplicationContext) {
ConfigurableApplicationContext context = (ConfigurableApplicationContext) applicationContext;
ServletContextDestroyedListener listener = new ServletContextDestroyedListener(context);
servletContext.addListener(listener);
}
}
private static class ServletContextDestroyedListener implements ServletContextListener {
private final ConfigurableApplicationContext applicationContext;
public ServletContextDestroyedListener(ConfigurableApplicationContext applicationContext) {
this.applicationContext = applicationContext;
}
@Override
public void contextInitialized(ServletContextEvent sce) {
}
@Override
public void contextDestroyed(ServletContextEvent sce) {
this.applicationContext.close();
}
}
AbstractServletHttpHandlerAdapterInitializer
在Servlet上下文中注册ServletHttpHandlerAdapter的WebApplicationInitializer实现的基类。
public abstract class AbstractServletHttpHandlerAdapterInitializer implements WebApplicationInitializer {
/**
* The default servlet name. Can be customized by overriding {@link #getServletName}.
*/
public static final String DEFAULT_SERVLET_NAME = "http-handler-adapter";
@Override
public void onStartup(ServletContext servletContext) throws ServletException {
registerHandlerAdapter(servletContext);
}
/**
* Register a {@link ServletHttpHandlerAdapter} against the given servlet context.
* <p>This method will create a {@code HttpHandler} using {@link #createHttpHandler()},
* and use it to create a {@code ServletHttpHandlerAdapter} with the name returned by
* {@link #getServletName()}, and mapping it to the patterns
* returned from {@link #getServletMappings()}.
* <p>Further customization can be achieved by overriding {@link
* #customizeRegistration(ServletRegistration.Dynamic)} or
* {@link #createServlet(HttpHandler)}.
* @param servletContext the context to register the servlet against
*/
protected void registerHandlerAdapter(ServletContext servletContext) {
String servletName = getServletName();
Assert.hasLength(servletName, "getServletName() must not return empty or null");
HttpHandler httpHandler = createHttpHandler();
Assert.notNull(httpHandler,
"createHttpHandler() did not return a HttpHandler for servlet [" + servletName + "]");
ServletHttpHandlerAdapter servlet = createServlet(httpHandler);
Assert.notNull(servlet,
"createHttpHandler() did not return a ServletHttpHandlerAdapter for servlet [" + servletName + "]");
ServletRegistration.Dynamic registration = servletContext.addServlet(servletName, servlet);
Assert.notNull(registration,
"Failed to register servlet with name '" + servletName + "'." +
"Check if there is another servlet registered under the same name.");
registration.setLoadOnStartup(1);
registration.addMapping(getServletMappings());
registration.setAsyncSupported(true);
customizeRegistration(registration);
}
/**
* Return the name under which the {@link ServletHttpHandlerAdapter} will be registered.
* Defaults to {@link #DEFAULT_SERVLET_NAME}.
* @see #registerHandlerAdapter(ServletContext)
*/
protected String getServletName() {
return DEFAULT_SERVLET_NAME;
}
/**
* Create the {@link HttpHandler}.
*/
protected abstract HttpHandler createHttpHandler();
/**
* Create a {@link ServletHttpHandlerAdapter} with the specified .
* <p>Default implementation returns a {@code ServletHttpHandlerAdapter} with the provided
* {@code httpHandler}.
*/
protected ServletHttpHandlerAdapter createServlet(HttpHandler httpHandler) {
return new ServletHttpHandlerAdapter(httpHandler);
}
/**
* Specify the servlet mapping(s) for the {@code ServletHttpHandlerAdapter} —
* for example {@code "/"}, {@code "/app"}, etc.
* @see #registerHandlerAdapter(ServletContext)
*/
protected abstract String[] getServletMappings();
/**
* Optionally perform further registration customization once
* {@link #registerHandlerAdapter(ServletContext)} has completed.
* @param registration the {@code DispatcherServlet} registration to be customized
* @see #registerHandlerAdapter(ServletContext)
*/
protected void customizeRegistration(ServletRegistration.Dynamic registration) {
}
}
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