com.hortonworks.streamline.common.util.ReflectionHelper.java Source code

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Here is the source code for com.hortonworks.streamline.common.util.ReflectionHelper.java

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/**
  * Copyright 2017 Hortonworks.
  *
  * 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 com.hortonworks.streamline.common.util;

import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider;
import org.springframework.core.type.filter.AnnotationTypeFilter;

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

public class ReflectionHelper {
    private static final Logger LOG = LoggerFactory.getLogger(ReflectionHelper.class);

    public static <T> T newInstance(String className)
            throws ClassNotFoundException, IllegalAccessException, InstantiationException {
        return (T) Class.forName(className).newInstance();
    }

    public static <T> T invokeGetter(String propertyName, Object object)
            throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
        String methodName = "get" + StringUtils.capitalize(propertyName);
        Method method = object.getClass().getMethod(methodName);
        return (T) method.invoke(object);
    }

    public static <T> T invokeSetter(String propertyName, Object object, Object valueToSet)
            throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
        String methodName = "set" + StringUtils.capitalize(propertyName);
        Method method = object.getClass().getMethod(methodName, valueToSet.getClass());
        return (T) method.invoke(object, valueToSet);
    }

    /**
     * Given a class, this method returns a map of names of all the instance (non static) fields -> type.
     * if the class has any super class it also includes those fields.
     * @param clazz , not null
     * @return
     */
    public static Map<String, Class> getFieldNamesToTypes(Class clazz) {
        Field[] declaredFields = clazz.getDeclaredFields();
        Map<String, Class> instanceVariableNamesToTypes = new HashMap<>();
        for (Field field : declaredFields) {
            if (!Modifier.isStatic(field.getModifiers())) {
                LOG.trace("clazz {} has field {} with type {}", clazz.getName(), field.getName(),
                        field.getType().getName());
                instanceVariableNamesToTypes.put(field.getName(), field.getType());
            } else {
                LOG.trace("clazz {} has field {} with type {}, which is static so ignoring", clazz.getName(),
                        field.getName(), field.getType().getName());
            }
        }

        if (!clazz.getSuperclass().equals(Object.class)) {
            instanceVariableNamesToTypes.putAll(getFieldNamesToTypes(clazz.getSuperclass()));
        }
        return instanceVariableNamesToTypes;
    }

    public static Collection<Class<?>> getAnnotatedClasses(String basePackage,
            Class<? extends Annotation> annotation) {
        Collection<Class<?>> classes = new ArrayList<>();
        ClassPathScanningCandidateComponentProvider provider = new ClassPathScanningCandidateComponentProvider(
                false);
        provider.addIncludeFilter(new AnnotationTypeFilter(annotation));
        for (BeanDefinition beanDef : provider.findCandidateComponents(basePackage)) {
            try {
                classes.add(Class.forName(beanDef.getBeanClassName()));
            } catch (ClassNotFoundException e) {
                throw new RuntimeException(e);
            }
        }
        return classes;
    }

}