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.web.method.HandlerMethod; 024import org.springframework.web.servlet.HandlerAdapter; 025import org.springframework.web.servlet.ModelAndView; 026import org.springframework.web.servlet.support.WebContentGenerator; 027 028/** 029 * Abstract base class for {@link HandlerAdapter} implementations that support 030 * handlers of type {@link HandlerMethod}. 031 * 032 * @author Arjen Poutsma 033 * @since 3.1 034 */ 035public abstract class AbstractHandlerMethodAdapter extends WebContentGenerator implements HandlerAdapter, Ordered { 036 037 private int order = Ordered.LOWEST_PRECEDENCE; 038 039 040 public AbstractHandlerMethodAdapter() { 041 // no restriction of HTTP methods by default 042 super(false); 043 } 044 045 046 /** 047 * Specify the order value for this HandlerAdapter bean. 048 * <p>The default value is {@code Ordered.LOWEST_PRECEDENCE}, meaning non-ordered. 049 * @see org.springframework.core.Ordered#getOrder() 050 */ 051 public void setOrder(int order) { 052 this.order = order; 053 } 054 055 @Override 056 public int getOrder() { 057 return this.order; 058 } 059 060 061 /** 062 * This implementation expects the handler to be an {@link HandlerMethod}. 063 * @param handler the handler instance to check 064 * @return whether or not this adapter can adapt the given handler 065 */ 066 @Override 067 public final boolean supports(Object handler) { 068 return (handler instanceof HandlerMethod && supportsInternal((HandlerMethod) handler)); 069 } 070 071 /** 072 * Given a handler method, return whether or not this adapter can support it. 073 * @param handlerMethod the handler method to check 074 * @return whether or not this adapter can adapt the given method 075 */ 076 protected abstract boolean supportsInternal(HandlerMethod handlerMethod); 077 078 /** 079 * This implementation expects the handler to be an {@link HandlerMethod}. 080 */ 081 @Override 082 public final ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) 083 throws Exception { 084 085 return handleInternal(request, response, (HandlerMethod) handler); 086 } 087 088 /** 089 * Use the given handler method to handle the request. 090 * @param request current HTTP request 091 * @param response current HTTP response 092 * @param handlerMethod handler method to use. This object must have previously been passed to the 093 * {@link #supportsInternal(HandlerMethod)} this interface, which must have returned {@code true}. 094 * @return ModelAndView object with the name of the view and the required model data, 095 * or {@code null} if the request has been handled directly 096 * @throws Exception in case of errors 097 */ 098 protected abstract ModelAndView handleInternal(HttpServletRequest request, 099 HttpServletResponse response, HandlerMethod handlerMethod) throws Exception; 100 101 /** 102 * This implementation expects the handler to be an {@link HandlerMethod}. 103 */ 104 @Override 105 public final long getLastModified(HttpServletRequest request, Object handler) { 106 return getLastModifiedInternal(request, (HandlerMethod) handler); 107 } 108 109 /** 110 * Same contract as for {@link javax.servlet.http.HttpServlet#getLastModified(HttpServletRequest)}. 111 * @param request current HTTP request 112 * @param handlerMethod handler method to use 113 * @return the lastModified value for the given handler 114 */ 115 protected abstract long getLastModifiedInternal(HttpServletRequest request, HandlerMethod handlerMethod); 116 117}