java复制对象，复制对象属性，只可复制两个对象想同的属性名。也可自定义只复制需要的属性。

注意：使用时copy（）方法只会复制相同的属性。常用的copy()方法。以下为封装的工具和使用方式。

1.封装类

import java.util.Map;

import java.util.WeakHashMap;

import org.springframework.cglib.beans.BeanCopier;
import org.springframework.cglib.core.Converter;
public class BeanCopyUtils {
// 使用WeakHashMap缓存,在内存不足时会自动释放
private final static Map<String, BeanCopier> BEAN_COPIER_MAP = new WeakHashMap<>();
private final static Map<String, Converter> CONVERTER_MAP = new WeakHashMap<>();
private static Object lock1 = new Object();
private static Object lock2 = new Object();

private BeanCopyUtils() {
}

/**
* 创建BeanCopier，并缓存
*
* @param src
* @param target
* @param useConverter
* @return
*/
private static BeanCopier getBeanCopier(Object src, Object target, boolean useConverter) {
String key = generateKey(src, target, useConverter);
BeanCopier bc = BEAN_COPIER_MAP.get(key);
if (null == bc) {
synchronized (lock1) {
bc = BEAN_COPIER_MAP.get(key);
if (null == bc) {
bc = BeanCopier.create(src.getClass(), target.getClass(), useConverter);
BEAN_COPIER_MAP.put(key, bc);
System.out.println("Create BeanCopier with key:" + key);
}
}
}
return bc;
}

/**
* 复制对象属性
*
* @param src
* @param target
*/
public static void copy(Object src, Object target) {
BeanCopier bc = getBeanCopier(src, target, false);
bc.copy(src, target, null);
}

/**
* 使用自定义的属性转换器复制对象属性
*
* @param src
* @param target
* @param converter
*/
public static void copy(Object src, Object target, Converter converter) {
BeanCopier bc = getBeanCopier(src, target, true);
bc.copy(src, target, converter);
}

/**
* 对象属性复制，只复制fields中指定的属性，每个属性用逗号分隔
*
* @param src
* @param target
* @param fields
*/
public static void copyWithFields(Object src, Object target, final String fields) {
BeanCopier bc = getBeanCopier(src, target, true);
bc.copy(src, target, newConverter(src, target, fields, true));
}

/**
* 对象属性复制，排除指定属性
*
* @param src
* @param target
* @param fields
*/
public static void copyWithoutFields(Object src, Object target, final String fields) {
BeanCopier bc = getBeanCopier(src, target, true);
bc.copy(src, target, newConverter(src, target, fields, false));
}

/**
* new属性转换器，
*
* @param fields
* 需要复制或排除的属性
* @param fieldCopyFlag
* 属性复制标识 true:表明fields为需要复制的属性；false:表明fields是需要排除复制的属性
* @return
*/
private static Converter newConverter(Object src, Object target, final String fields, final boolean fieldCopyFlag) {
String key = buildConverterkey(src, target, fields, fieldCopyFlag);
Converter converter = CONVERTER_MAP.get(key);
if (null == converter) {
synchronized (lock2) {
converter = CONVERTER_MAP.get(key);
if (null == converter) {
converter = new Converter() {
@Override
public Object convert(Object fieldValue, Class fieldType, Object methodName) {
String field = methodName.toString().substring(3); // 得到属性名，如Name
field = field.substring(0, 1).toLowerCase() + field.substring(1); // 将首字母小写
if ((fieldCopyFlag && fields.contains(field))
|| (!fieldCopyFlag && !fields.contains(field))) {
return fieldValue;
}
return null;
}
};
CONVERTER_MAP.put(key, converter);
System.out.println("Created Converter with key:" + key);
}
}
}
return converter;
}

private static String generateKey(Object src, Object target, boolean useConverter) {
return src.getClass().getName() + target.getClass().getName() + String.valueOf(useConverter);
}

private static String buildConverterkey(Object src, Object target, String fields, boolean copyFlag) {
String baseKey = generateKey(src, target, true);
String key = baseKey + fields + String.valueOf(copyFlag);
return key;
}

}

2.使用实例

FileCabinet fb = list.get(i);
FileCabinetReturn fbReturn = new FileCabinetReturn();
BeanCopyUtils.copy(fb, fbReturn);