org.springframework.core.MethodParameter Maven / Gradle / Ivy
/*
* Copyright 2002-2018 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
*
* https://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.annotation.Annotation;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Constructor;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.HashMap;
import java.util.Map;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
/**
* Helper class that encapsulates the specification of a method parameter, i.e. a {@link Method}
* or {@link Constructor} plus a parameter index and a nested type index for a declared generic
* type. Useful as a specification object to pass along.
*
* As of 4.2, there is a {@link org.springframework.core.annotation.SynthesizingMethodParameter}
* subclass available which synthesizes annotations with attribute aliases. That subclass is used
* for web and message endpoint processing, in particular.
*
* @author Juergen Hoeller
* @author Rob Harrop
* @author Andy Clement
* @author Sam Brannen
* @since 2.0
* @see org.springframework.core.annotation.SynthesizingMethodParameter
*/
public class MethodParameter {
private static final Annotation[] EMPTY_ANNOTATION_ARRAY = new Annotation[0];
private static final Class javaUtilOptionalClass;
static {
Class clazz;
try {
clazz = ClassUtils.forName("java.util.Optional", MethodParameter.class.getClassLoader());
}
catch (ClassNotFoundException ex) {
// Java 8 not available - Optional references simply not supported then.
clazz = null;
}
javaUtilOptionalClass = clazz;
}
private final Method method;
private final Constructor constructor;
private final int parameterIndex;
private int nestingLevel = 1;
/** Map from Integer level to Integer type index */
Map typeIndexesPerLevel;
private volatile Class containingClass;
private volatile Class parameterType;
private volatile Type genericParameterType;
private volatile Annotation[] parameterAnnotations;
private volatile ParameterNameDiscoverer parameterNameDiscoverer;
private volatile String parameterName;
private volatile MethodParameter nestedMethodParameter;
/**
* Create a new {@code 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: -1 for the method
* return type; 0 for the first method parameter; 1 for the second method
* parameter, etc.
*/
public MethodParameter(Method method, int parameterIndex) {
this(method, parameterIndex, 1);
}
/**
* Create a new {@code 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;
this.constructor = null;
}
/**
* 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;
this.method = null;
}
/**
* 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.nestingLevel = original.nestingLevel;
this.typeIndexesPerLevel = original.typeIndexesPerLevel;
this.containingClass = original.containingClass;
this.parameterType = original.parameterType;
this.genericParameterType = original.genericParameterType;
this.parameterAnnotations = original.parameterAnnotations;
this.parameterNameDiscoverer = original.parameterNameDiscoverer;
this.parameterName = original.parameterName;
}
/**
* Return the wrapped Method, if any.
* Note: Either Method or Constructor is available.
* @return the Method, or {@code null} if none
*/
public Method getMethod() {
return this.method;
}
/**
* Return the wrapped Constructor, if any.
*
Note: Either Method or Constructor is available.
* @return the Constructor, or {@code null} if none
*/
public Constructor getConstructor() {
return this.constructor;
}
/**
* Return the class that declares the underlying Method or Constructor.
*/
public Class getDeclaringClass() {
return getMember().getDeclaringClass();
}
/**
* Return the wrapped member.
* @return the Method or Constructor as Member
*/
public Member getMember() {
// NOTE: no ternary expression to retain JDK <8 compatibility even when using
// the JDK 8 compiler (potentially selecting java.lang.reflect.Executable
// as common type, with that new base class not available on older JDKs)
if (this.method != null) {
return this.method;
}
else {
return this.constructor;
}
}
/**
* Return the wrapped annotated element.
*
Note: This method exposes the annotations declared on the method/constructor
* itself (i.e. at the method/constructor level, not at the parameter level).
* @return the Method or Constructor as AnnotatedElement
*/
public AnnotatedElement getAnnotatedElement() {
// NOTE: no ternary expression to retain JDK <8 compatibility even when using
// the JDK 8 compiler (potentially selecting java.lang.reflect.Executable
// as common type, with that new base class not available on older JDKs)
if (this.method != null) {
return this.method;
}
else {
return this.constructor;
}
}
/**
* Return the index of the method/constructor parameter.
* @return the parameter index (-1 in case of the return type)
*/
public int getParameterIndex() {
return this.parameterIndex;
}
/**
* 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(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} for the default type index)
* @see #getNestingLevel()
*/
public void setTypeIndexForCurrentLevel(int typeIndex) {
getTypeIndexesPerLevel().put(this.nestingLevel, typeIndex);
}
/**
* Return the type index for the current nesting level.
* @return the corresponding type index, or {@code null}
* 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}
* if none specified (indicating the default type index)
*/
public Integer getTypeIndexForLevel(int nestingLevel) {
return getTypeIndexesPerLevel().get(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;
}
/**
* Return a variant of this {@code MethodParameter} which points to the
* same parameter but one nesting level deeper. This is effectively the
* same as {@link #increaseNestingLevel()}, just with an independent
* {@code MethodParameter} object (e.g. in case of the original being cached).
* @since 4.3
*/
public MethodParameter nested() {
if (this.nestedMethodParameter != null) {
return this.nestedMethodParameter;
}
MethodParameter nestedParam = clone();
nestedParam.nestingLevel = this.nestingLevel + 1;
this.nestedMethodParameter = nestedParam;
return nestedParam;
}
/**
* Return whether this method parameter is declared as optional
* in the form of Java 8's {@link java.util.Optional}.
* @since 4.3
*/
public boolean isOptional() {
return (getParameterType() == javaUtilOptionalClass);
}
/**
* Return a variant of this {@code MethodParameter} which points to
* the same parameter but one nesting level deeper in case of a
* {@link java.util.Optional} declaration.
* @since 4.3
* @see #isOptional()
* @see #nested()
*/
public MethodParameter nestedIfOptional() {
return (isOptional() ? nested() : this);
}
/**
* Set a containing class to resolve the parameter type against.
*/
void setContainingClass(Class containingClass) {
this.containingClass = containingClass;
}
public Class getContainingClass() {
return (this.containingClass != null ? this.containingClass : getDeclaringClass());
}
/**
* 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})
*/
public Class getParameterType() {
Class paramType = this.parameterType;
if (paramType == null) {
if (this.parameterIndex < 0) {
Method method = getMethod();
paramType = (method != null ? method.getReturnType() : void.class);
}
else {
paramType = (this.method != null ?
this.method.getParameterTypes()[this.parameterIndex] :
this.constructor.getParameterTypes()[this.parameterIndex]);
}
this.parameterType = paramType;
}
return paramType;
}
/**
* Return the generic type of the method/constructor parameter.
* @return the parameter type (never {@code null})
* @since 3.0
*/
public Type getGenericParameterType() {
Type paramType = this.genericParameterType;
if (paramType == null) {
if (this.parameterIndex < 0) {
Method method = getMethod();
paramType = (method != null ? method.getGenericReturnType() : void.class);
}
else {
Type[] genericParameterTypes = (this.method != null ?
this.method.getGenericParameterTypes() : this.constructor.getGenericParameterTypes());
int index = this.parameterIndex;
if (this.constructor != null && this.constructor.getDeclaringClass().isMemberClass() &&
!Modifier.isStatic(this.constructor.getDeclaringClass().getModifiers()) &&
genericParameterTypes.length == this.constructor.getParameterTypes().length - 1) {
// Bug in javac: type array excludes enclosing instance parameter
// for inner classes with at least one generic constructor parameter,
// so access it with the actual parameter index lowered by 1
index = this.parameterIndex - 1;
}
paramType = (index >= 0 && index < genericParameterTypes.length ?
genericParameterTypes[index] : getParameterType());
}
this.genericParameterType = paramType;
}
return paramType;
}
/**
* Return the nested type of the method/constructor parameter.
* @return the parameter type (never {@code null})
* @since 3.1
* @see #getNestingLevel()
*/
public Class getNestedParameterType() {
if (this.nestingLevel > 1) {
Type type = getGenericParameterType();
for (int i = 2; i <= this.nestingLevel; i++) {
if (type instanceof ParameterizedType) {
Type[] args = ((ParameterizedType) type).getActualTypeArguments();
Integer index = getTypeIndexForLevel(i);
type = args[index != null ? index : args.length - 1];
}
// TODO: Object.class if unresolvable
}
if (type instanceof Class) {
return (Class) type;
}
else if (type instanceof ParameterizedType) {
Type arg = ((ParameterizedType) type).getRawType();
if (arg instanceof Class) {
return (Class) arg;
}
}
return Object.class;
}
else {
return getParameterType();
}
}
/**
* Return the nested generic type of the method/constructor parameter.
* @return the parameter type (never {@code null})
* @since 4.2
* @see #getNestingLevel()
*/
public Type getNestedGenericParameterType() {
if (this.nestingLevel > 1) {
Type type = getGenericParameterType();
for (int i = 2; i <= this.nestingLevel; i++) {
if (type instanceof ParameterizedType) {
Type[] args = ((ParameterizedType) type).getActualTypeArguments();
Integer index = getTypeIndexForLevel(i);
type = args[index != null ? index : args.length - 1];
}
}
return type;
}
else {
return getGenericParameterType();
}
}
/**
* Return the annotations associated with the target method/constructor itself.
*/
public Annotation[] getMethodAnnotations() {
return adaptAnnotationArray(getAnnotatedElement().getAnnotations());
}
/**
* Return the method/constructor annotation of the given type, if available.
* @param annotationType the annotation type to look for
* @return the annotation object, or {@code null} if not found
*/
public A getMethodAnnotation(Class annotationType) {
return adaptAnnotation(getAnnotatedElement().getAnnotation(annotationType));
}
/**
* Return whether the method/constructor is annotated with the given type.
* @param annotationType the annotation type to look for
* @since 4.3
* @see #getMethodAnnotation(Class)
*/
public boolean hasMethodAnnotation(Class annotationType) {
return getAnnotatedElement().isAnnotationPresent(annotationType);
}
/**
* Return the annotations associated with the specific method/constructor parameter.
*/
public Annotation[] getParameterAnnotations() {
Annotation[] paramAnns = this.parameterAnnotations;
if (paramAnns == null) {
Annotation[][] annotationArray = (this.method != null ?
this.method.getParameterAnnotations() : this.constructor.getParameterAnnotations());
int index = this.parameterIndex;
if (this.constructor != null && this.constructor.getDeclaringClass().isMemberClass() &&
!Modifier.isStatic(this.constructor.getDeclaringClass().getModifiers()) &&
annotationArray.length == this.constructor.getParameterTypes().length - 1) {
// Bug in javac in JDK <9: annotation array excludes enclosing instance parameter
// for inner classes, so access it with the actual parameter index lowered by 1
index = this.parameterIndex - 1;
}
paramAnns = (index >= 0 && index < annotationArray.length ?
adaptAnnotationArray(annotationArray[index]) : EMPTY_ANNOTATION_ARRAY);
this.parameterAnnotations = paramAnns;
}
return paramAnns;
}
/**
* Return {@code true} if the parameter has at least one annotation,
* {@code false} if it has none.
* @see #getParameterAnnotations()
*/
public boolean hasParameterAnnotations() {
return (getParameterAnnotations().length != 0);
}
/**
* Return the parameter annotation of the given type, if available.
* @param annotationType the annotation type to look for
* @return the annotation object, or {@code null} if not found
*/
@SuppressWarnings("unchecked")
public A getParameterAnnotation(Class annotationType) {
Annotation[] anns = getParameterAnnotations();
for (Annotation ann : anns) {
if (annotationType.isInstance(ann)) {
return (A) ann;
}
}
return null;
}
/**
* Return whether the parameter is declared with the given annotation type.
* @param annotationType the annotation type to look for
* @see #getParameterAnnotation(Class)
*/
public boolean hasParameterAnnotation(Class annotationType) {
return (getParameterAnnotation(annotationType) != null);
}
/**
* Initialize parameter name discovery for this method parameter.
* 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} 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() {
ParameterNameDiscoverer discoverer = this.parameterNameDiscoverer;
if (discoverer != null) {
String[] parameterNames = (this.method != null ?
discoverer.getParameterNames(this.method) : discoverer.getParameterNames(this.constructor));
if (parameterNames != null) {
this.parameterName = parameterNames[this.parameterIndex];
}
this.parameterNameDiscoverer = null;
}
return this.parameterName;
}
/**
* A template method to post-process a given annotation instance before
* returning it to the caller.
*