001/* 002 * Copyright 2002-2018 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.web.servlet.mvc.method; 018 019import javax.servlet.http.HttpServletRequest; 020import javax.servlet.http.HttpServletResponse; 021 022import org.springframework.core.Ordered; 023import org.springframework.lang.Nullable; 024import org.springframework.web.method.HandlerMethod; 025import org.springframework.web.servlet.HandlerAdapter; 026import org.springframework.web.servlet.ModelAndView; 027import org.springframework.web.servlet.support.WebContentGenerator; 028 029/** 030 * Abstract base class for {@link HandlerAdapter} implementations that support 031 * handlers of type {@link HandlerMethod}. 032 * 033 * @author Arjen Poutsma 034 * @since 3.1 035 */ 036public abstract class AbstractHandlerMethodAdapter extends WebContentGenerator implements HandlerAdapter, Ordered { 037 038 private int order = Ordered.LOWEST_PRECEDENCE; 039 040 041 public AbstractHandlerMethodAdapter() { 042 // no restriction of HTTP methods by default 043 super(false); 044 } 045 046 047 /** 048 * Specify the order value for this HandlerAdapter bean. 049 * <p>The default value is {@code Ordered.LOWEST_PRECEDENCE}, meaning non-ordered. 050 * @see org.springframework.core.Ordered#getOrder() 051 */ 052 public void setOrder(int order) { 053 this.order = order; 054 } 055 056 @Override 057 public int getOrder() { 058 return this.order; 059 } 060 061 062 /** 063 * This implementation expects the handler to be an {@link HandlerMethod}. 064 * @param handler the handler instance to check 065 * @return whether or not this adapter can adapt the given handler 066 */ 067 @Override 068 public final boolean supports(Object handler) { 069 return (handler instanceof HandlerMethod && supportsInternal((HandlerMethod) handler)); 070 } 071 072 /** 073 * Given a handler method, return whether or not this adapter can support it. 074 * @param handlerMethod the handler method to check 075 * @return whether or not this adapter can adapt the given method 076 */ 077 protected abstract boolean supportsInternal(HandlerMethod handlerMethod); 078 079 /** 080 * This implementation expects the handler to be an {@link HandlerMethod}. 081 */ 082 @Override 083 @Nullable 084 public final ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) 085 throws Exception { 086 087 return handleInternal(request, response, (HandlerMethod) handler); 088 } 089 090 /** 091 * Use the given handler method to handle the request. 092 * @param request current HTTP request 093 * @param response current HTTP response 094 * @param handlerMethod handler method to use. This object must have previously been passed to the 095 * {@link #supportsInternal(HandlerMethod)} this interface, which must have returned {@code true}. 096 * @return a ModelAndView object with the name of the view and the required model data, 097 * or {@code null} if the request has been handled directly 098 * @throws Exception in case of errors 099 */ 100 @Nullable 101 protected abstract ModelAndView handleInternal(HttpServletRequest request, 102 HttpServletResponse response, HandlerMethod handlerMethod) throws Exception; 103 104 /** 105 * This implementation expects the handler to be an {@link HandlerMethod}. 106 */ 107 @Override 108 public final long getLastModified(HttpServletRequest request, Object handler) { 109 return getLastModifiedInternal(request, (HandlerMethod) handler); 110 } 111 112 /** 113 * Same contract as for {@link javax.servlet.http.HttpServlet#getLastModified(HttpServletRequest)}. 114 * @param request current HTTP request 115 * @param handlerMethod handler method to use 116 * @return the lastModified value for the given handler 117 */ 118 protected abstract long getLastModifiedInternal(HttpServletRequest request, HandlerMethod handlerMethod); 119 120}