Java Reflection Generic Type from Class getGenericTypeForMapProperty(Class javaClass, String propertyName, boolean isKeyType)

Description

get Generic Type For Map Property

License

Apache License

Declaration

public static Class getGenericTypeForMapProperty(Class javaClass,
            String propertyName, boolean isKeyType) 

Method Source Code

//package com.java2s;
/* Copyright (C) 2011 SpringSource
 *
 * 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.//from  w  ww.j a  va  2  s.co  m
 */

import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;

public class Main {
    public static Class getGenericTypeForMapProperty(Class javaClass,
            String propertyName, boolean isKeyType) {
        Class genericClass = null;

        Field declaredField = getDeclaredField(javaClass, propertyName);
        Type genericType = declaredField != null ? declaredField
                .getGenericType() : null;
        if (genericType instanceof ParameterizedType) {
            Type[] typeArguments = ((ParameterizedType) genericType)
                    .getActualTypeArguments();
            if (typeArguments.length > 0) {
                Type typeArg = typeArguments[isKeyType ? 0 : 1];
                if (typeArg instanceof Class) {
                    genericClass = (Class) typeArg;
                }
            }
        }
        return genericClass;
    }

    /**
     * Get a declared field, searching super classes for the field if it is not found in the class.
     * @param javaClass The class to search.
     * @param propertyName The name of the field.
     * @return The field, or null if it couldn't be found.
     */
    public static Field getDeclaredField(Class javaClass,
            String propertyName) {
        while (javaClass != null) {
            Field[] declaredFields = javaClass.getDeclaredFields();
            for (Field declaredField : declaredFields) {
                if (declaredField.getName().equals(propertyName)) {
                    return declaredField;
                }
            }
            javaClass = javaClass.getSuperclass();
        }
        return null;
    }

    public static Class getGenericType(Class propertyType) {
        Class genericType = null;
        TypeVariable[] typeParameters = propertyType.getTypeParameters();
        if (typeParameters != null && typeParameters.length > 0) {
            Type[] bounds = typeParameters[0].getBounds();
            if (bounds != null && bounds.length > 0
                    && (bounds[0] instanceof Class)) {
                genericType = (Class) bounds[0];
            }
        }
        return genericType;
    }
}

Related

1. getGenericTypeArgument(Class clazz, int index)
2. getGenericTypeArgumentFromGenericSuperType(Type genericSuperclass, Class baseRequested)
3. getGenericTypeArgumentsOfInheritedType(final Object object, final Class inheritedType)
4. getGenericTypeClass(Class clazz, int index)
5. getGenericTypeClasses(List> genericTypeClasses, Type... genericTypes)
6. getGenericTypeOfInterface(Class clazz, Class specificInterface)
7. getGenericTypeOfParameter(Class clazz, String method, int parameterIndex)
8. getGenericTypeParameter(Class aClass, Class genericClass, int index)
9. getGenericTypes(Class c)