SpringMVC适配器类型汇总

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1.继承Controller方式所使用的适配器：SimpleControllerHandlerAdapter

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);
    }
}

2.继承HTTP请求处理器的适配器：HttpRequestHandlerAdapter

public class HttpRequestHandlerAdapter implements HandlerAdapter{
    public boolean supports(Object handler) {
        return (handler instanceof HttpRequestHandler);
    }
    public ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        ((HttpRequestHandler) handler).handleRequest(request, response);
        return null;
    }
}

3.注解方式（@Controller）的处理器适配器：RequestMappingHandlerAdapter

public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter{
    protected boolean supportsInternal(HandlerMethod handlerMethod) {
        return true;
    }
    protected ModelAndView handleInternal(HttpServletRequest request,
            HttpServletResponse response, HandlerMethod handlerMethod) throws Exception {
        return invokeHandlerMethod(request, response, handlerMethod);
    }
}
public  abstract class AbstractHandlerMethodAdapter implements HandlerAdapter{
    public final boolean supports(Object handler) {
        return (handler instanceof HandlerMethod && supportsInternal((HandlerMethod) handler));
    }
    public final ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {

        return handleInternal(request, response, (HandlerMethod) handler);
    }
}

4.继承servlet方式的适配器：SimpleServletHandlerAdapter

public class SimpleServletHandlerAdapter implements HandlerAdapter {
    public boolean supports(Object handler) {
        return (handler instanceof Servlet);
    }
    public ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        ((Servlet) handler).service(request, response);
        return null;
    }
}

为什么SpringMVC需要使用适配器调用handler具体方法

if(hanlder instanceof Controller){
 // 执行Controller适配器
}
if(hanlder instanceof  HttpControler){
 // 执行我们的HttpController
}
if(hanlder instanceof  ServletControler){
 // 执行我们的HttpController
}
if(hanlder instanceof  AnnotationControler){
 // 执行我们的AnnotationController
}

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