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.core.convert;
018
019import java.lang.annotation.Annotation;
020import java.lang.reflect.AnnotatedElement;
021import java.lang.reflect.Field;
022import java.lang.reflect.Method;
023import java.util.LinkedHashMap;
024import java.util.Map;
025
026import org.springframework.core.MethodParameter;
027import org.springframework.lang.Nullable;
028import org.springframework.util.ConcurrentReferenceHashMap;
029import org.springframework.util.ObjectUtils;
030import org.springframework.util.ReflectionUtils;
031import org.springframework.util.StringUtils;
032
033/**
034 * A description of a JavaBeans Property that allows us to avoid a dependency on
035 * {@code java.beans.PropertyDescriptor}. The {@code java.beans} package
036 * is not available in a number of environments (e.g. Android, Java ME), so this is
037 * desirable for portability of Spring's core conversion facility.
038 *
039 * <p>Used to build a {@link TypeDescriptor} from a property location. The built
040 * {@code TypeDescriptor} can then be used to convert from/to the property type.
041 *
042 * @author Keith Donald
043 * @author Phillip Webb
044 * @since 3.1
045 * @see TypeDescriptor#TypeDescriptor(Property)
046 * @see TypeDescriptor#nested(Property, int)
047 */
048public final class Property {
049
050        private static Map<Property, Annotation[]> annotationCache = new ConcurrentReferenceHashMap<>();
051
052        private final Class<?> objectType;
053
054        @Nullable
055        private final Method readMethod;
056
057        @Nullable
058        private final Method writeMethod;
059
060        private final String name;
061
062        private final MethodParameter methodParameter;
063
064        @Nullable
065        private Annotation[] annotations;
066
067
068        public Property(Class<?> objectType, @Nullable Method readMethod, @Nullable Method writeMethod) {
069                this(objectType, readMethod, writeMethod, null);
070        }
071
072        public Property(
073                        Class<?> objectType, @Nullable Method readMethod, @Nullable Method writeMethod, @Nullable String name) {
074
075                this.objectType = objectType;
076                this.readMethod = readMethod;
077                this.writeMethod = writeMethod;
078                this.methodParameter = resolveMethodParameter();
079                this.name = (name != null ? name : resolveName());
080        }
081
082
083        /**
084         * The object declaring this property, either directly or in a superclass the object extends.
085         */
086        public Class<?> getObjectType() {
087                return this.objectType;
088        }
089
090        /**
091         * The name of the property: e.g. 'foo'
092         */
093        public String getName() {
094                return this.name;
095        }
096
097        /**
098         * The property type: e.g. {@code java.lang.String}
099         */
100        public Class<?> getType() {
101                return this.methodParameter.getParameterType();
102        }
103
104        /**
105         * The property getter method: e.g. {@code getFoo()}
106         */
107        @Nullable
108        public Method getReadMethod() {
109                return this.readMethod;
110        }
111
112        /**
113         * The property setter method: e.g. {@code setFoo(String)}
114         */
115        @Nullable
116        public Method getWriteMethod() {
117                return this.writeMethod;
118        }
119
120
121        // package private
122
123        MethodParameter getMethodParameter() {
124                return this.methodParameter;
125        }
126
127        Annotation[] getAnnotations() {
128                if (this.annotations == null) {
129                        this.annotations = resolveAnnotations();
130                }
131                return this.annotations;
132        }
133
134
135        // internal helpers
136
137        private String resolveName() {
138                if (this.readMethod != null) {
139                        int index = this.readMethod.getName().indexOf("get");
140                        if (index != -1) {
141                                index += 3;
142                        }
143                        else {
144                                index = this.readMethod.getName().indexOf("is");
145                                if (index == -1) {
146                                        throw new IllegalArgumentException("Not a getter method");
147                                }
148                                index += 2;
149                        }
150                        return StringUtils.uncapitalize(this.readMethod.getName().substring(index));
151                }
152                else if (this.writeMethod != null) {
153                        int index = this.writeMethod.getName().indexOf("set");
154                        if (index == -1) {
155                                throw new IllegalArgumentException("Not a setter method");
156                        }
157                        index += 3;
158                        return StringUtils.uncapitalize(this.writeMethod.getName().substring(index));
159                }
160                else {
161                        throw new IllegalStateException("Property is neither readable nor writeable");
162                }
163        }
164
165        private MethodParameter resolveMethodParameter() {
166                MethodParameter read = resolveReadMethodParameter();
167                MethodParameter write = resolveWriteMethodParameter();
168                if (write == null) {
169                        if (read == null) {
170                                throw new IllegalStateException("Property is neither readable nor writeable");
171                        }
172                        return read;
173                }
174                if (read != null) {
175                        Class<?> readType = read.getParameterType();
176                        Class<?> writeType = write.getParameterType();
177                        if (!writeType.equals(readType) && writeType.isAssignableFrom(readType)) {
178                                return read;
179                        }
180                }
181                return write;
182        }
183
184        @Nullable
185        private MethodParameter resolveReadMethodParameter() {
186                if (getReadMethod() == null) {
187                        return null;
188                }
189                return new MethodParameter(getReadMethod(), -1).withContainingClass(getObjectType());
190        }
191
192        @Nullable
193        private MethodParameter resolveWriteMethodParameter() {
194                if (getWriteMethod() == null) {
195                        return null;
196                }
197                return new MethodParameter(getWriteMethod(), 0).withContainingClass(getObjectType());
198        }
199
200        private Annotation[] resolveAnnotations() {
201                Annotation[] annotations = annotationCache.get(this);
202                if (annotations == null) {
203                        Map<Class<? extends Annotation>, Annotation> annotationMap = new LinkedHashMap<>();
204                        addAnnotationsToMap(annotationMap, getReadMethod());
205                        addAnnotationsToMap(annotationMap, getWriteMethod());
206                        addAnnotationsToMap(annotationMap, getField());
207                        annotations = annotationMap.values().toArray(new Annotation[0]);
208                        annotationCache.put(this, annotations);
209                }
210                return annotations;
211        }
212
213        private void addAnnotationsToMap(
214                        Map<Class<? extends Annotation>, Annotation> annotationMap, @Nullable AnnotatedElement object) {
215
216                if (object != null) {
217                        for (Annotation annotation : object.getAnnotations()) {
218                                annotationMap.put(annotation.annotationType(), annotation);
219                        }
220                }
221        }
222
223        @Nullable
224        private Field getField() {
225                String name = getName();
226                if (!StringUtils.hasLength(name)) {
227                        return null;
228                }
229                Field field = null;
230                Class<?> declaringClass = declaringClass();
231                if (declaringClass != null) {
232                        field = ReflectionUtils.findField(declaringClass, name);
233                        if (field == null) {
234                                // Same lenient fallback checking as in CachedIntrospectionResults...
235                                field = ReflectionUtils.findField(declaringClass, StringUtils.uncapitalize(name));
236                                if (field == null) {
237                                        field = ReflectionUtils.findField(declaringClass, StringUtils.capitalize(name));
238                                }
239                        }
240                }
241                return field;
242        }
243
244        @Nullable
245        private Class<?> declaringClass() {
246                if (getReadMethod() != null) {
247                        return getReadMethod().getDeclaringClass();
248                }
249                else if (getWriteMethod() != null) {
250                        return getWriteMethod().getDeclaringClass();
251                }
252                else {
253                        return null;
254                }
255        }
256
257
258        @Override
259        public boolean equals(@Nullable Object other) {
260                if (this == other) {
261                        return true;
262                }
263                if (!(other instanceof Property)) {
264                        return false;
265                }
266                Property otherProperty = (Property) other;
267                return (ObjectUtils.nullSafeEquals(this.objectType, otherProperty.objectType) &&
268                                ObjectUtils.nullSafeEquals(this.name, otherProperty.name) &&
269                                ObjectUtils.nullSafeEquals(this.readMethod, otherProperty.readMethod) &&
270                                ObjectUtils.nullSafeEquals(this.writeMethod, otherProperty.writeMethod));
271        }
272
273        @Override
274        public int hashCode() {
275                return (ObjectUtils.nullSafeHashCode(this.objectType) * 31 + ObjectUtils.nullSafeHashCode(this.name));
276        }
277
278}