freework.reflect.Parameter Maven / Gradle / Ivy
/*
* Copyright (c) 2005, 2014 vacoor
*
* Licensed under the Apache License, Version 2.0 (the "License");
*/
package freework.reflect;
import java.lang.annotation.Annotation;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Method;
import java.lang.reflect.Type;
import java.util.HashMap;
import java.util.Map;
/**
* Represents a method parameter.
*
* Parameter.lookup(method)[0].isCompatible(Object.class);
*
*
* @author vacoor
* @since 1.0
*/
public class Parameter implements AnnotatedElement {
/**
* The method declaring this parameter.
*/
private final Method method;
/**
* The index of the parameter.
*/
private final int index;
/**
* The declared annotations of this parameter.
*/
private final Map, Annotation> declaredAnnotations = new HashMap, Annotation>();
/**
* Lookup parameters object from specified method.
*
* @param method the method
* @return the parameters
*/
public static Parameter[] lookup(final Method method) {
if (null == method) {
throw new IllegalArgumentException("method must not be null");
}
final Class[] types = method.getParameterTypes();
final Parameter[] params = new Parameter[types.length];
for (int i = 0; i < types.length; i++) {
params[i] = new Parameter(method, i);
}
return params;
}
/**
* Creates a parameter instance.
*
* @param method the method which defines this parameter
* @param index the index of this parameter
*/
private Parameter(final Method method, final int index) {
this.method = method;
this.index = index;
final Annotation[] annotations = method.getParameterAnnotations()[index];
for (final Annotation anno : annotations) {
this.declaredAnnotations.put(anno.annotationType(), anno);
}
}
/**
* Return the method which declares this parameter.
*
* @return the method declaring this parameter.
*/
public Method getDeclaringMethod() {
return method;
}
/**
* The index of the parameter.
*
* @return the index of the parameter
*/
public int getIndex() {
return index;
}
/**
* Returns the declared type for this parameter.
*
* @return the declared type for this parameter.
*/
public Class getType() {
return method.getParameterTypes()[index];
}
/**
* Returns the parameterized type for this parameter.
*
* @return the parameterized type for this parameter
*/
public Type getParameterizedType() {
return method.getGenericParameterTypes()[index];
}
/**
* Returns true if this parameter represents a variable argument list; returns false otherwise.
*
* @return true if an only if this parameter represents a variable argument list.
*/
public boolean isVarArgs() {
return method.isVarArgs() && index == method.getParameterTypes().length - 1;
}
/**
* Whether the parameter is compatible with the value of the given type.
*
* @param type the actual type
* @return true if can apply
*/
public boolean isCompatible(final Class type) {
return getType().isAssignableFrom(type);
}
/**
* {@inheritDoc}
*/
@Override
public boolean isAnnotationPresent(final Class annotationClass) {
return getAnnotation(annotationClass) != null;
}
/**
* {@inheritDoc}
*/
@Override
@SuppressWarnings("unchecked")
public T getAnnotation(final Class annotationClass) {
return (T) declaredAnnotations.get(annotationClass);
}
/**
* {@inheritDoc}
*/
@Override
public Annotation[] getAnnotations() {
return method.getParameterAnnotations()[index];
}
/**
* {@inheritDoc}
*/
@Override
public Annotation[] getDeclaredAnnotations() {
return getAnnotations();
}
}