SpringMVC源碼解析AbstractHandlerMethodAdapter

AbstractHandlerMethodAdapter是HandlerAdapter接口的簡單抽象類，實現了接口定義的方法,同時增加了執行順序Order。

public abstract class AbstractHandlerMethodAdapter extends WebContentGenerator implements HandlerAdapter, Ordered {  
    private int order = Ordered.LOWEST_PRECEDENCE;  
    public AbstractHandlerMethodAdapter() {  
        // no restriction of HTTP methods by default  
        super(false);  
    }  
    @Override  
    public final boolean supports(Object handler) {  
        return (handler instanceof HandlerMethod && supportsInternal((HandlerMethod) handler));  
    }  
    protected abstract boolean supportsInternal(HandlerMethod handlerMethod);  


    //重寫HandlerAdapter的handle方法
    @Override  
    public final ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler)  
            throws Exception {  
  
        return handleInternal(request, response, (HandlerMethod) handler);  
    }  
    // (1)備好處理器所需要的參數
    // (2)使用處理器處理請求
    // (3)處理返回值，將不同類型的返回值統一處理成ModelAndView
    protected abstract ModelAndView handleInternal(HttpServletRequest request,  
            HttpServletResponse response, HandlerMethod handlerMethod) throws Exception;  
  
    @Override  
    public final long getLastModified(HttpServletRequest request, Object handler) {  
        return getLastModifiedInternal(request, (HandlerMethod) handler);  
    }  
    //提供order功能
    public void setOrder(int order) {  
        this.order = order;  
    }  
    @Override  
    public int getOrder() {  
        return this.order;  
    }  
    protected abstract long getLastModifiedInternal(HttpServletRequest request, HandlerMethod handlerMethod);  
  
}  

handleInternal由唯一子類RequestMappingHandlerAdapter實現。