【SpringMVC】DispatcherServlet重要组件之一HandlerAdapter_dispacherservlet handleradapter-优快云博客

本文介绍了Spring MVC框架中的核心组件HandlerAdapter接口及其实现SimpleControllerHandlerAdapter。文章详细解释了HandlerAdapter的作用，包括supports方法、handle方法及getLastModified方法的功能，并展示了如何通过实现这些方法来处理请求。

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作用使用处理器干活的。共三个方法：

package org.springframework.web.servlet;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public interface HandlerAdapter {
	
	boolean supports(Object handler);
	ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception;

	long getLastModified(HttpServletRequest request, Object handler);

}

例子：

public class SimpleControllerHandlerAdapter implements HandlerAdapter {

	public boolean supports(Object handler) {
		return (handler instanceof Controller);
	}

	public ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler)
			throws Exception {

		return ((Controller) handler).handleRequest(request, response);
	}

	public long getLastModified(HttpServletRequest request, Object handler) {
		if (handler instanceof LastModified) {
			return ((LastModified) handler).getLastModified(request);
		}
		return -1L;
	}

}

getHandlerAdapter方法也是按顺序遍历：

protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
		for (HandlerMapping hm : this.handlerMappings) {
			if (logger.isTraceEnabled()) {
				logger.trace(
						"Testing handler map [" + hm + "] in DispatcherServlet with name '" + getServletName() + "'");
			}
			HandlerExecutionChain handler = hm.getHandler(request);
			if (handler != null) {
				return handler;
			}
		}
		return null;
	}