001/* 002 * Copyright 2002-2019 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.ui; 018 019import java.util.Collection; 020import java.util.LinkedHashMap; 021import java.util.Map; 022 023import org.springframework.core.Conventions; 024import org.springframework.lang.Nullable; 025import org.springframework.util.Assert; 026 027/** 028 * Implementation of {@link java.util.Map} for use when building model data for use 029 * with UI tools. Supports chained calls and generation of model attribute names. 030 * 031 * <p>This class serves as generic model holder for Servlet MVC but is not tied to it. 032 * Check out the {@link Model} interface for an interface variant. 033 * 034 * @author Rob Harrop 035 * @author Juergen Hoeller 036 * @since 2.0 037 * @see Conventions#getVariableName 038 * @see org.springframework.web.servlet.ModelAndView 039 */ 040@SuppressWarnings("serial") 041public class ModelMap extends LinkedHashMap<String, Object> { 042 043 /** 044 * Construct a new, empty {@code ModelMap}. 045 */ 046 public ModelMap() { 047 } 048 049 /** 050 * Construct a new {@code ModelMap} containing the supplied attribute 051 * under the supplied name. 052 * @see #addAttribute(String, Object) 053 */ 054 public ModelMap(String attributeName, @Nullable Object attributeValue) { 055 addAttribute(attributeName, attributeValue); 056 } 057 058 /** 059 * Construct a new {@code ModelMap} containing the supplied attribute. 060 * Uses attribute name generation to generate the key for the supplied model 061 * object. 062 * @see #addAttribute(Object) 063 */ 064 public ModelMap(Object attributeValue) { 065 addAttribute(attributeValue); 066 } 067 068 069 /** 070 * Add the supplied attribute under the supplied name. 071 * @param attributeName the name of the model attribute (never {@code null}) 072 * @param attributeValue the model attribute value (can be {@code null}) 073 */ 074 public ModelMap addAttribute(String attributeName, @Nullable Object attributeValue) { 075 Assert.notNull(attributeName, "Model attribute name must not be null"); 076 put(attributeName, attributeValue); 077 return this; 078 } 079 080 /** 081 * Add the supplied attribute to this {@code Map} using a 082 * {@link org.springframework.core.Conventions#getVariableName generated name}. 083 * <p><i>Note: Empty {@link Collection Collections} are not added to 084 * the model when using this method because we cannot correctly determine 085 * the true convention name. View code should check for {@code null} rather 086 * than for empty collections as is already done by JSTL tags.</i> 087 * @param attributeValue the model attribute value (never {@code null}) 088 */ 089 public ModelMap addAttribute(Object attributeValue) { 090 Assert.notNull(attributeValue, "Model object must not be null"); 091 if (attributeValue instanceof Collection && ((Collection<?>) attributeValue).isEmpty()) { 092 return this; 093 } 094 return addAttribute(Conventions.getVariableName(attributeValue), attributeValue); 095 } 096 097 /** 098 * Copy all attributes in the supplied {@code Collection} into this 099 * {@code Map}, using attribute name generation for each element. 100 * @see #addAttribute(Object) 101 */ 102 public ModelMap addAllAttributes(@Nullable Collection<?> attributeValues) { 103 if (attributeValues != null) { 104 for (Object attributeValue : attributeValues) { 105 addAttribute(attributeValue); 106 } 107 } 108 return this; 109 } 110 111 /** 112 * Copy all attributes in the supplied {@code Map} into this {@code Map}. 113 * @see #addAttribute(String, Object) 114 */ 115 public ModelMap addAllAttributes(@Nullable Map<String, ?> attributes) { 116 if (attributes != null) { 117 putAll(attributes); 118 } 119 return this; 120 } 121 122 /** 123 * Copy all attributes in the supplied {@code Map} into this {@code Map}, 124 * with existing objects of the same name taking precedence (i.e. not getting 125 * replaced). 126 */ 127 public ModelMap mergeAttributes(@Nullable Map<String, ?> attributes) { 128 if (attributes != null) { 129 attributes.forEach((key, value) -> { 130 if (!containsKey(key)) { 131 put(key, value); 132 } 133 }); 134 } 135 return this; 136 } 137 138 /** 139 * Does this model contain an attribute of the given name? 140 * @param attributeName the name of the model attribute (never {@code null}) 141 * @return whether this model contains a corresponding attribute 142 */ 143 public boolean containsAttribute(String attributeName) { 144 return containsKey(attributeName); 145 } 146 147 /** 148 * Return the attribute value for the given name, if any. 149 * @param attributeName the name of the model attribute (never {@code null}) 150 * @return the corresponding attribute value, or {@code null} if none 151 * @since 5.2 152 */ 153 @Nullable 154 public Object getAttribute(String attributeName) { 155 return get(attributeName); 156 } 157 158}