对象拷贝，用于更新时

import org.apache.log4j.Logger;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.security.AccessController;
import java.security.PrivilegedAction;

public class ObjectCopyUtils {

    private static Logger logger = Logger.getLogger(ObjectCopyUtils.class.getName());
    private static Object source;
    private static Object target;
    private static ObjectCopyType objectCopyType;

    public enum ObjectCopyType{
        SOURCE_NOT_NULL,
        TARGET_IS_NULL,
        ALL
    }

    private ObjectCopyUtils(){

    }

    /**
     * @param paramSource 源对象
     * @param paramTarget 目标对象
     * @param paramObjectCopyType 操作类型 0： 如果源对象的当前i的属性的值不为null，才copy过去. 1：如果目标对象的当前i的属性的值为null，才copy过去.2.默认，所有都copy过去
     * @throws IllegalAccessException
     * @throws IllegalArgumentException
     */
    public static void copyProperties(Object paramSource, Object paramTarget, ObjectCopyType paramObjectCopyType){
        source = paramSource;
        target = paramTarget;
        objectCopyType = paramObjectCopyType;
        if(source==null || target==null || objectCopyType==null){
            return;
        }

        AccessController.doPrivileged(
                new PrivilegedAction() {   //NOSONAR
                    public Object run() {
                        Class objClass = source.getClass();
                        Class tarClass = target.getClass();

                        // 通过target对象的class到obj的class中逐个扫描有无相同的field类型
                        Field[] tarFields = tarClass.getDeclaredFields();
                        for(int i=0; i<tarFields.length; i++){
                            String fieldName = tarFields[i].getName();
                            try {
                                Field objField = objClass.getDeclaredField(fieldName);

                                objField.setAccessible(true);
                                tarFields[i].setAccessible(true);

                                Object sourceValue = objField.get(source);
                                Object tarValue = tarFields[i].get(target);

                                if(tarFields[i].getModifiers() >= Modifier.FINAL){
                                    continue; //final 属性不能修改
                                }

                                switch (objectCopyType){
                                    case SOURCE_NOT_NULL:
                                        //如果源对象的当前i的属性的值不为空，才复制过去.
                                        if(sourceValue != null){
                                            tarFields[i].set(target, sourceValue);
                                        }
                                        break;
                                    case TARGET_IS_NULL:
                                        //如果目标对象的当前i的属性的值为空，才复制过去.
                                        if(tarValue == null){
                                            tarFields[i].set(target, sourceValue);
                                        }
                                        break;
                                    default:
                                        //所有复制过去
                                        tarFields[i].set(target, sourceValue);
                                        break;
                                }
                            } catch (Exception e) {     //NOSONAR
                                logger.error("ObjectCopyUtils.class copyProperties error" , e);
                                continue;
                            }
                        }
                        return  null;
                    }
                });
    }
}