/*
* Copyright 2002-2010 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.core.convert;
import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import org.springframework.core.GenericCollectionTypeResolver;
import org.springframework.core.MethodParameter;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.CollectionUtils;
import org.springframework.util.ObjectUtils;
/**
* Context about a type to convert to.
*
* @author Keith Donald
* @author Andy Clement
* @author Juergen Hoeller
* @since 3.0
*/
public class TypeDescriptor {
/** Constant defining a TypeDescriptor for a <code>null</code> value */
public static final TypeDescriptor NULL = new TypeDescriptor();
/** Constant defining a TypeDescriptor for 'unknown type' */
private static final TypeDescriptor UNKNOWN = new TypeDescriptor(Object.class);
private static final Map<Class<?>, TypeDescriptor> typeDescriptorCache = new HashMap<Class<?>, TypeDescriptor>();
private static final Annotation[] EMPTY_ANNOTATION_ARRAY = new Annotation[0];
static {
typeDescriptorCache.put(boolean.class, new TypeDescriptor(boolean.class));
typeDescriptorCache.put(Boolean.class, new TypeDescriptor(Boolean.class));
typeDescriptorCache.put(byte.class, new TypeDescriptor(byte.class));
typeDescriptorCache.put(Byte.class, new TypeDescriptor(Byte.class));
typeDescriptorCache.put(char.class, new TypeDescriptor(char.class));
typeDescriptorCache.put(Character.class, new TypeDescriptor(Character.class));
typeDescriptorCache.put(short.class, new TypeDescriptor(short.class));
typeDescriptorCache.put(Short.class, new TypeDescriptor(Short.class));
typeDescriptorCache.put(int.class, new TypeDescriptor(int.class));
typeDescriptorCache.put(Integer.class, new TypeDescriptor(Integer.class));
typeDescriptorCache.put(long.class, new TypeDescriptor(long.class));
typeDescriptorCache.put(Long.class, new TypeDescriptor(Long.class));
typeDescriptorCache.put(float.class, new TypeDescriptor(float.class));
typeDescriptorCache.put(Float.class, new TypeDescriptor(Float.class));
typeDescriptorCache.put(double.class, new TypeDescriptor(double.class));
typeDescriptorCache.put(Double.class, new TypeDescriptor(Double.class));
typeDescriptorCache.put(String.class, new TypeDescriptor(String.class));
}
private Class<?> type;
private MethodParameter methodParameter;
private Field field;
private int fieldNestingLevel = 1;
private Object value;
private TypeDescriptor elementType;
private TypeDescriptor mapKeyType;
private TypeDescriptor mapValueType;
private Annotation[] annotations;
/**
* Create a new type descriptor from a method or constructor parameter.
* <p>Use this constructor when a target conversion point originates from a method parameter,
* such as a setter method argument.
* @param methodParameter the MethodParameter to wrap
*/
public TypeDescriptor(MethodParameter methodParameter) {
Assert.notNull(methodParameter, "MethodParameter must not be null");
this.methodParameter = methodParameter;
}
/**
* Create a new type descriptor for a field.
* Use this constructor when a target conversion point originates from a field.
* @param field the field to wrap
*/
public TypeDescriptor(Field field) {
Assert.notNull(field, "Field must not be null");
this.field = field;
}
/**
* Create a new type descriptor from a method or constructor parameter.
* <p>Use this constructor when a target conversion point originates from a method parameter,
* such as a setter method argument.
* @param methodParameter the MethodParameter to wrap
* @param type the specific type to expose (may be an array/collection element)
*/
public TypeDescriptor(MethodParameter methodParameter, Class<?> type) {
Assert.notNull(methodParameter, "MethodParameter must not be null");
this.methodParameter = methodParameter;
this.type = type;
}
/**
* Create a new type descriptor for a field.
* Use this constructor when a target conversion point originates from a field.
* @param field the field to wrap
* @param type the specific type to expose (may be an array/collection element)
*/
public TypeDescriptor(Field field, Class<?> type) {
Assert.notNull(field, "Field must not be null");
this.field = field;
this.type = type;
}
/**
* Create a new type descriptor for a field.
* Use this constructor when a target conversion point originates from a field.
* @param field the field to wrap
* @param type the specific type to expose (may be an array/collection element)
*/
private TypeDescriptor(Field field, int nestingLevel, Class<?> type) {
Assert.notNull(field, "Field must not be null");
this.field = field;
this.fieldNestingLevel = nestingLevel;
this.type = type;
}
/**
* Internal constructor for a NULL descriptor.
*/
private TypeDescriptor() {
}
/**
* Create a new descriptor for the type of the given value.
* <p>Use this constructor when a conversion point comes from a source such as a Map or
* Collection, where no additional context is available but elements can be introspected.
* @param value the value to determine the actual type from
*/
private TypeDescriptor(Object value) {
Assert.notNull(value, "Value must not be null");
this.value = value;
this.type = value.getClass();
}
/**
* Create a new descriptor for the given type.
* <p>Use this constructor when a conversion point comes from a plain source type,
* where no additional context is available.
* @param type the actual type to wrap
*/
private TypeDescriptor(Class<?> type) {
Assert.notNull(type, "Type must not be null");
this.type = type;
}
/**
* Return the wrapped MethodParameter, if any.
* <p>Note: Either MethodParameter or Field is available.
* @return the MethodParameter, or <code>null</code> if none
*/
public MethodParameter getMethodParameter() {
return this.methodParameter;
}
/**
* Return the wrapped Field, if any.
* <p>Note: Either MethodParameter or Field is available.
* @return the Field, or <code>null</code> if none
*/
public Field getField() {
return this.field;
}
/**
* Determine the declared (non-generic) type of the wrapped parameter/field.
* @return the declared type, or <code>null</code> if this is {@link TypeDescriptor#NULL}
*/
public Class<?> getType() {
if (this.type != null) {
return this.type;
}
else if (this.field != null) {
return this.field.getType();
}
else if (this.methodParameter != null) {
return this.methodParameter.getParameterType();
}
else {
return null;
}
}
/**
* Determine the declared type of the wrapped parameter/field.
* Returns the Object wrapper type if the underlying type is a primitive.
*/
public Class<?> getObjectType() {
Class<?> type = getType();
return (type != null ? ClassUtils.resolvePrimitiveIfNecessary(type) : type);
}
/**
* Returns the name of this type: the fully qualified class name.
*/
public String getName() {
Class<?> type = getType();
return (type != null ? ClassUtils.getQualifiedName(type) : null);
}
/**
* Is this type a primitive type?
*/
public boolean isPrimitive() {
Class<?> type = getType();
return (type != null && type.isPrimitive());
}
/**
* Is this type an array type?
*/
public boolean isArray() {
Class<?> type = getType();
return (type != null && type.isArray());
}
/**
* Is this type a {@link Collection} type?
*/
public boolean isCollection() {
return Collection.class.isAssignableFrom(getType());
}
/**
* If this type is an array type or {@link Collection} type, returns the underlying element type.
* Returns <code>null</code> if the type is neither an array or collection.
*/
public Class<?> getElementType() {
return getElementTypeDescriptor().getType();
}
/**
* Return the element type as a type descriptor.
*/
public synchronized TypeDescriptor getElementTypeDescriptor() {
if (this.elementType == null) {
this.elementType = forElementType(resolveElementType());
}
return this.elementType;
}
/**
* Return the element type as a type descriptor. If the element type is null
* (cannot be determined), the type descriptor is derived from the element argument.
* @param element the element
* @return the element type descriptor
*/
public TypeDescriptor getElementTypeDescriptor(Object element) {
TypeDescriptor elementType = getElementTypeDescriptor();
return (elementType != TypeDescriptor.UNKNOWN ? elementType : forObject(element));
}
/**
* Is this type a {@link Map} type?
*/
public boolean isMap() {
return Map.class.isAssignableFrom(getType());
}
/**
* Is this descriptor for a map where the key type and value type are known?
*/
public boolean isMapEntryTypeKnown() {
return (isMap() && getMapKeyType() != null && getMapValueType() != null);
}
/**
* Determine the generic key type of the wrapped Map parameter/field, if any.
* @return the generic type, or <code>null</code> if none
*/
public Class<?> getMapKeyType() {
return getMapKeyTypeDescriptor().getType();
}
/**
* Returns map key type as a type descriptor.
*/
public synchronized TypeDescriptor getMapKeyTypeDescriptor() {
if (this.mapKeyType == null) {
this.mapKeyType = forElementType(resolveMapKeyType());
}
return this.mapKeyType;
}
/**
* Return the map key type as a type descriptor. If the key type is null
* (cannot be determined), the type descriptor is derived from the key argument.
* @param key the key
* @return the map key type descriptor
*/
public TypeDescriptor getMapKeyTypeDescriptor(Object key) {
TypeDescriptor keyType = getMapKeyTypeDescriptor();
return (keyType != TypeDescriptor.UNKNOWN ? keyType : TypeDescriptor.forObject(key));
}
/**
* Determine the generic value type of the wrapped Map parameter/field, if any.
* @return the generic type, or <code>null</code> if none
*/
public Class<?> getMapValueType() {
return getMapValueTypeDescriptor().getType();
}
/**
* Returns map value type as a type descriptor.
*/
public synchronized TypeDescriptor getMapValueTypeDescriptor() {
if (this.mapValueType == null) {
this.mapValueType = forElementType(resolveMapValueType());
}
return this.mapValueType;
}
/**
* Return the map value type as a type descriptor. If the value type is null
* (cannot be determined), the type descriptor is derived from the value argument.
* @param value the value
* @return the map value type descriptor
*/
public TypeDescriptor getMapValueTypeDescriptor(Object value) {
TypeDescriptor valueType = getMapValueTypeDescriptor();
return (valueType != TypeDescriptor.UNKNOWN ? valueType : TypeDescriptor.forObject(value));
}
/**
* Obtain the annotations associated with the wrapped parameter/field, if any.
*/
public synchronized Annotation[] getAnnotations() {
if (this.annotations == null) {
this.annotations = resolveAnnotations();
}
return this.annotations;
}
/**
* Obtain the annotation associated with the wrapped parameter/field, if any.
*/
public Annotation getAnnotation(Class<? extends Annotation> annotationType) {
for (Annotation annotation : getAnnotations()) {
if (annotation.annotationType().equals(annotationType)) {
return annotation;
}
}
return null;
}
/**
* Returns true if an object of this type can be assigned to a reference of given targetType.
* @param targetType the target type
* @return true if this type is assignable to the target
*/
public boolean isAssignableTo(TypeDescriptor targetType) {
if (this == TypeDescriptor.NULL || targetType == TypeDescriptor.NULL) {
return true;
}
if (isCollection() && targetType.isCollection() || isArray() && targetType.isArray()) {
return targetType.getType().isAssignableFrom(getType()) &&
getElementTypeDescriptor().isAssignableTo(targetType.getElementTypeDescriptor());
}
else if (isMap() && targetType.isMap()) {
return targetType.getType().isAssignableFrom(getType()) &&
getMapKeyTypeDescriptor().isAssignableTo(targetType.getMapKeyTypeDescriptor()) &&
getMapValueTypeDescriptor().isAssignableTo(targetType.getMapValueTypeDescriptor());
}
else {
return targetType.getObjectType().isAssignableFrom(getObjectType());
}
}
/**
* Create a copy of this type descriptor, preserving the context information
* but exposing the specified element type (e.g. an array/collection/map element).
* @param elementType the desired type to expose
* @return the type descriptor
*/
public TypeDescriptor forElementType(Class<?> elementType) {
if (elementType == null) {
return TypeDescriptor.UNKNOWN;
}
else if (this.methodParameter != null) {
MethodParameter nested = new MethodParameter(this.methodParameter);
nested.increaseNestingLevel();
return new TypeDescriptor(nested, elementType);
}
else if (this.field != null) {
return new TypeDescriptor(this.field, this.fieldNestingLevel + 1, elementType);
}
else {
return TypeDescriptor.valueOf(elementType);
}
}
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (!(obj instanceof TypeDescriptor) || obj == TypeDescriptor.NULL) {
return false;
}
TypeDescriptor other = (TypeDescriptor) obj;
boolean annotatedTypeEquals =
getType().equals(other.getType()) && ObjectUtils.nullSafeEquals(getAnnotations(), other.getAnnotations());
if (isCollection()) {
return annotatedTypeEquals && ObjectUtils.nullSafeEquals(getElementType(), other.getElementType());
}
else if (isMap()) {
return annotatedTypeEquals && ObjectUtils.nullSafeEquals(getMapKeyType(), other.getMapKeyType()) &&
ObjectUtils.nullSafeEquals(getMapValueType(), other.getMapValueType());
}
else {
return annotatedTypeEquals;
}
}
public int hashCode() {
return (this == TypeDescriptor.NULL ? 0 : getType().hashCode());
}
/**
* A textual representation of the type descriptor (eg. Map<String,Foo>) for use in messages.
*/
public String asString() {
return toString();
}
public String toString() {
if (this == TypeDescriptor.NULL) {
return "null";
}
else {
StringBuilder builder = new StringBuilder();
Annotation[] anns = getAnnotations();
for (Annotation ann : anns) {
builder.append("@").append(ann.annotationType().getName()).append(' ');
}
builder.append(ClassUtils.getQualifiedName(getType()));
if (isMap()) {
builder.append("<").append(getMapKeyTypeDescriptor());
builder.append(", ").append(getMapValueTypeDescriptor()).append(">");
}
else if (isCollection()) {
builder.append("<").append(getElementTypeDescriptor()).append(">");
}
return builder.toString();
}
}
// internal helpers
private Class<?> resolveElementType() {
if (isArray()) {
return getType().getComponentType();
}
else if (isCollection()) {
return resolveCollectionElementType();
}
else {
return null;
}
}
@SuppressWarnings("unchecked")
private Class<?> resolveCollectionElementType() {
if (this.field != null) {
return GenericCollectionTypeResolver.getCollectionFieldType(this.field, this.fieldNestingLevel);
}
else if (this.methodParameter != null) {
return GenericCollectionTypeResolver.getCollectionParameterType(this.methodParameter);
}
else if (this.value instanceof Collection) {
Class<?> elementType = CollectionUtils.findCommonElementType((Collection) this.value);
if (elementType != null) {
return elementType;
}
}
else if (this.type != null) {
return GenericCollectionTypeResolver.getCollectionType((Class<? extends Collection>) this.type);
}
return null;
}
@SuppressWarnings("unchecked")
private Class<?> resolveMapKeyType() {
if (this.field != null) {
return GenericCollectionTypeResolver.getMapKeyFieldType(this.field);
}
else if (this.methodParameter != null) {
return GenericCollectionTypeResolver.getMapKeyParameterType(this.methodParameter);
}
else if (this.value instanceof Map<?, ?>) {
Class<?> keyType = CollectionUtils.findCommonElementType(((Map<?, ?>) this.value).keySet());
if (keyType != null) {
return keyType;
}
}
else if (this.type != null && isMap()) {
return GenericCollectionTypeResolver.getMapKeyType((Class<? extends Map>) this.type);
}
return null;
}
@SuppressWarnings("unchecked")
private Class<?> resolveMapValueType() {
if (this.field != null) {
return GenericCollectionTypeResolver.getMapValueFieldType(this.field);
}
else if (this.methodParameter != null) {
return GenericCollectionTypeResolver.getMapValueParameterType(this.methodParameter);
}
else if (this.value instanceof Map<?, ?>) {
Class<?> valueType = CollectionUtils.findCommonElementType(((Map<?, ?>) this.value).values());
if (valueType != null) {
return valueType;
}
}
else if (this.type != null && isMap()) {
return GenericCollectionTypeResolver.getMapValueType((Class<? extends Map>) this.type);
}
return null;
}
private Annotation[] resolveAnnotations() {
if (this.field != null) {
return this.field.getAnnotations();
}
else if (this.methodParameter != null) {
if (this.methodParameter.getParameterIndex() < 0) {
return this.methodParameter.getMethodAnnotations();
}
else {
return this.methodParameter.getParameterAnnotations();
}
}
else {
return EMPTY_ANNOTATION_ARRAY;
}
}
// static factory methods
/**
* Create a new type descriptor for the class of the given object.
* @param object the object
* @return the type descriptor
*/
public static TypeDescriptor forObject(Object object) {
if (object == null) {
return NULL;
}
else if (object instanceof Collection<?> || object instanceof Map<?, ?>) {
return new TypeDescriptor(object);
}
else {
return valueOf(object.getClass());
}
}
/**
* Create a new type descriptor for the given class.
* @param type the class
* @return the type descriptor
*/
public static TypeDescriptor valueOf(Class<?> type) {
if (type == null) {
return TypeDescriptor.NULL;
}
TypeDescriptor desc = typeDescriptorCache.get(type);
return (desc != null ? desc : new TypeDescriptor(type));
}
}
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