/*
* Copyright 2002-2008 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;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.ReflectionUtils;
/**
* Helper class that encapsulates the specification of a method parameter, i.e.
* a Method or Constructor plus a parameter index and a nested type index for
* a declared generic type. Useful as a specification object to pass along.
*
* <p>Used by {@link GenericCollectionTypeResolver},
* {@link org.springframework.beans.BeanWrapperImpl} and
* {@link org.springframework.beans.factory.support.AbstractBeanFactory}.
*
* <p>Note that this class does not depend on JDK 1.5 API artifacts, in order
* to remain compatible with JDK 1.4. Concrete generic type resolution
* via JDK 1.5 API happens in {@link GenericCollectionTypeResolver} only.
*
* @author Juergen Hoeller
* @author Rob Harrop
* @since 2.0
* @see GenericCollectionTypeResolver
*/
public class MethodParameter {
private static final Method methodParameterAnnotationsMethod =
ClassUtils.getMethodIfAvailable(Method.class, "getParameterAnnotations", new Class[0]);
private static final Method constructorParameterAnnotationsMethod =
ClassUtils.getMethodIfAvailable(Constructor.class, "getParameterAnnotations", new Class[0]);
private Method method;
private Constructor constructor;
private final int parameterIndex;
private Class parameterType;
private Object[] parameterAnnotations;
private ParameterNameDiscoverer parameterNameDiscoverer;
private String parameterName;
private int nestingLevel = 1;
/** Map from Integer level to Integer type index */
private Map typeIndexesPerLevel;
Map typeVariableMap;
/**
* Create a new MethodParameter for the given method, with nesting level 1.
* @param method the Method to specify a parameter for
* @param parameterIndex the index of the parameter
*/
public MethodParameter(Method method, int parameterIndex) {
this(method, parameterIndex, 1);
}
/**
* Create a new MethodParameter for the given method.
* @param method the Method to specify a parameter for
* @param parameterIndex the index of the parameter
* (-1 for the method return type; 0 for the first method parameter,
* 1 for the second method parameter, etc)
* @param nestingLevel the nesting level of the target type
* (typically 1; e.g. in case of a List of Lists, 1 would indicate the
* nested List, whereas 2 would indicate the element of the nested List)
*/
public MethodParameter(Method method, int parameterIndex, int nestingLevel) {
Assert.notNull(method, "Method must not be null");
this.method = method;
this.parameterIndex = parameterIndex;
this.nestingLevel = nestingLevel;
}
/**
* Create a new MethodParameter for the given constructor, with nesting level 1.
* @param constructor the Constructor to specify a parameter for
* @param parameterIndex the index of the parameter
*/
public MethodParameter(Constructor constructor, int parameterIndex) {
this(constructor, parameterIndex, 1);
}
/**
* Create a new MethodParameter for the given constructor.
* @param constructor the Constructor to specify a parameter for
* @param parameterIndex the index of the parameter
* @param nestingLevel the nesting level of the target type
* (typically 1; e.g. in case of a List of Lists, 1 would indicate the
* nested List, whereas 2 would indicate the element of the nested List)
*/
public MethodParameter(Constructor constructor, int parameterIndex, int nestingLevel) {
Assert.notNull(constructor, "Constructor must not be null");
this.constructor = constructor;
this.parameterIndex = parameterIndex;
this.nestingLevel = nestingLevel;
}
/**
* Copy constructor, resulting in an independent MethodParameter object
* based on the same metadata and cache state that the original object was in.
* @param original the original MethodParameter object to copy from
*/
public MethodParameter(MethodParameter original) {
Assert.notNull(original, "Original must not be null");
this.method = original.method;
this.constructor = original.constructor;
this.parameterIndex = original.parameterIndex;
this.parameterType = original.parameterType;
this.parameterAnnotations = original.parameterAnnotations;
this.typeVariableMap = original.typeVariableMap;
}
/**
* Return the wrapped Method, if any.
* <p>Note: Either Method or Constructor is available.
* @return the Method, or <code>null</code> if none
*/
public Method getMethod() {
return this.method;
}
/**
* Return the wrapped Constructor, if any.
* <p>Note: Either Method or Constructor is available.
* @return the Constructor, or <code>null</code> if none
*/
public Constructor getConstructor() {
return this.constructor;
}
/**
* Return the index of the method/constructor parameter.
* @return the parameter index (never negative)
*/
public int getParameterIndex() {
return this.parameterIndex;
}
/**
* Set a resolved (generic) parameter type.
*/
void setParameterType(Class parameterType) {
this.parameterType = parameterType;
}
/**
* Return the type of the method/constructor parameter.
* @return the parameter type (never <code>null</code>)
*/
public Class getParameterType() {
if (this.parameterType == null) {
if (this.parameterIndex < 0) {
this.parameterType = (this.method != null ? this.method.getReturnType() : null);
}
else {
this.parameterType = (this.method != null ?
this.method.getParameterTypes()[this.parameterIndex] :
this.constructor.getParameterTypes()[this.parameterIndex]);
}
}
return this.parameterType;
}
/**
* Return the annotations associated with the method/constructor parameter.
* @return the parameter annotations, or <code>null</code> if there is
* no annotation support (on JDK < 1.5). The return value is an Object array
* instead of an Annotation array simply for compatibility with older JDKs;
* feel free to cast it to <code>Annotation[]</code> on JDK 1.5 or higher.
*/
public Object[] getParameterAnnotations() {
if (this.parameterAnnotations != null) {
return this.parameterAnnotations;
}
if (methodParameterAnnotationsMethod == null) {
return null;
}
Object[][] annotationArray = (this.method != null ?
((Object[][]) ReflectionUtils.invokeMethod(methodParameterAnnotationsMethod, this.method)) :
((Object[][]) ReflectionUtils.invokeMethod(constructorParameterAnnotationsMethod, this.constructor)));
this.parameterAnnotations = annotationArray[this.parameterIndex];
return this.parameterAnnotations;
}
/**
* Initialize parameter name discovery for this method parameter.
* <p>This method does not actually try to retrieve the parameter name at
* this point; it just allows discovery to happen when the application calls
* {@link #getParameterName()} (if ever).
*/
public void initParameterNameDiscovery(ParameterNameDiscoverer parameterNameDiscoverer) {
this.parameterNameDiscoverer = parameterNameDiscoverer;
}
/**
* Return the name of the method/constructor parameter.
* @return the parameter name (may be <code>null</code> if no
* parameter name metadata is contained in the class file or no
* {@link #initParameterNameDiscovery ParameterNameDiscoverer}
* has been set to begin with)
*/
public String getParameterName() {
if (this.parameterNameDiscoverer != null) {
String[] parameterNames = (this.method != null ?
this.parameterNameDiscoverer.getParameterNames(this.method) :
this.parameterNameDiscoverer.getParameterNames(this.constructor));
if (parameterNames != null) {
this.parameterName = parameterNames[this.parameterIndex];
}
this.parameterNameDiscoverer = null;
}
return this.parameterName;
}
/**
* Increase this parameter's nesting level.
* @see #getNestingLevel()
*/
public void increaseNestingLevel() {
this.nestingLevel++;
}
/**
* Decrease this parameter's nesting level.
* @see #getNestingLevel()
*/
public void decreaseNestingLevel() {
getTypeIndexesPerLevel().remove(new Integer(this.nestingLevel));
this.nestingLevel--;
}
/**
* Return the nesting level of the target type
* (typically 1; e.g. in case of a List of Lists, 1 would indicate the
* nested List, whereas 2 would indicate the element of the nested List).
*/
public int getNestingLevel() {
return this.nestingLevel;
}
/**
* Set the type index for the current nesting level.
* @param typeIndex the corresponding type index
* (or <code>null</code> for the default type index)
* @see #getNestingLevel()
*/
public void setTypeIndexForCurrentLevel(int typeIndex) {
getTypeIndexesPerLevel().put(new Integer(this.nestingLevel), new Integer(typeIndex));
}
/**
* Return the type index for the current nesting level.
* @return the corresponding type index, or <code>null</code>
* if none specified (indicating the default type index)
* @see #getNestingLevel()
*/
public Integer getTypeIndexForCurrentLevel() {
return getTypeIndexForLevel(this.nestingLevel);
}
/**
* Return the type index for the specified nesting level.
* @param nestingLevel the nesting level to check
* @return the corresponding type index, or <code>null</code>
* if none specified (indicating the default type index)
*/
public Integer getTypeIndexForLevel(int nestingLevel) {
return (Integer) getTypeIndexesPerLevel().get(new Integer(nestingLevel));
}
/**
* Obtain the (lazily constructed) type-indexes-per-level Map.
*/
private Map getTypeIndexesPerLevel() {
if (this.typeIndexesPerLevel == null) {
this.typeIndexesPerLevel = new HashMap(4);
}
return this.typeIndexesPerLevel;
}
/**
* Create a new MethodParameter for the given method or constructor.
* <p>This is a convenience constructor for scenarios where a
* Method or Constructor reference is treated in a generic fashion.
* @param methodOrConstructor the Method or Constructor to specify a parameter for
* @param parameterIndex the index of the parameter
* @return the corresponding MethodParameter instance
*/
public static MethodParameter forMethodOrConstructor(Object methodOrConstructor, int parameterIndex) {
if (methodOrConstructor instanceof Method) {
return new MethodParameter((Method) methodOrConstructor, parameterIndex);
}
else if (methodOrConstructor instanceof Constructor) {
return new MethodParameter((Constructor) methodOrConstructor, parameterIndex);
}
else {
throw new IllegalArgumentException(
"Given object [" + methodOrConstructor + "] is neither a Method nor a Constructor");
}
}
}