springMVC源码分析--HttpRequestHandlerAdapter（四）

上一篇博客springMVC源码分析--HandlerAdapter（一）中我们主要介绍了一下HandlerAdapter接口相关的内容，实现类及其在DispatcherServlet中执行的顺序，接下来我们详细介绍一下其实现类HttpRequestHandlerAdapter，同前几篇博客一样HttpRequestHandlerAdapter的本质还是调用HttpRequestHandler的HttpRequestHandler方法。
supports方法就是判断handler是否是ServletgetLastModified直接值handle方法本质是执行HttpRequestHandler.handleRequest方法。源码如下：public class HttpRequestHandlerAdapter implements HandlerAdapter {
@Override
public boolean supports(Object handler) {
//判断是否是HttpRequestHandler子类
return (handler instanceof HttpRequestHandler);
}
@Override
public ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler)
throws Exception {
//执行HttpRequestHandler的handleRequest方法
((HttpRequestHandler) handler).handleRequest(request, response);
return null;
}
@Override
public long getLastModified(HttpServletRequest request, Object handler) {
//返回modified值
if (handler instanceof LastModified) {
return ((LastModified) handler).getLastModified(request);
}
return -1L;
}
}本质HttpRequestHandlerAdapter是HttpRequestHandler的适配器，最终调用HttpRequestHandler的handleRequest方法。
接口HttpRequestHandler的实现如下：public interface HttpRequestHandler {

void handleRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException;
}