java对象的克隆以及属性之间的克隆操作

本文深入探讨了Java Bean工具类中的对象复制、属性比较与属性复制方法,详细解释了如何通过这些工具类进行对象复制、比较不同属性值并将其复制到其他Bean中。
常用的类
apache下beanutils工具类
org.apache.commons.beanutils.BeanUtils

/**
* 复制对象obj,类似于值传递,非引用
*/
private Object cloneObject(Object obj) throws Exception {
ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
ObjectOutputStream out = new ObjectOutputStream(byteOut);
out.writeObject(obj);
ByteArrayInputStream byteIn = new ByteArrayInputStream(byteOut.toByteArray());
ObjectInputStream in = new ObjectInputStream(byteIn);
return in.readObject();
}


/**
* 比较同一类型class,orig 中非NULL值的属性和dest不同的值到resultBean里面
*
* @param dest 要比较的BEAN
* @param orig 原来BEAN
* @param result 结果BEAN
* @throws InvocationTargetException
* @throws IllegalAccessException
*/
public static void differBeanNotNullPropertyToOtherBean(Object dest, Object orig , Object result) throws IllegalAccessException,
InvocationTargetException {
// Validate existence of the specified beans
if (dest == null) {
throw new IllegalArgumentException("No destination bean specified");
}
if (orig == null) {
throw new IllegalArgumentException("No origin bean specified");
}
if (result == null) {
throw new IllegalArgumentException("No result bean specified");
}

if (!dest.getClass().toString().equals(orig.getClass().toString())) {
throw new IllegalArgumentException("No same bean class");
}
if (orig instanceof Map) {
throw new IllegalArgumentException("No support map");
}

/* if (orig is a standard JavaBean) */
PropertyDescriptor origDescriptors[] = PropertyUtils.getPropertyDescriptors(orig);
for (int i = 0; i < origDescriptors.length; i++) {
String name = origDescriptors[i].getName();
if ("class".equals(name)) {
continue; // No point in trying to set an object's class
}
if (PropertyUtils.isReadable(orig, name) && PropertyUtils.isWriteable(dest, name)) {
try {
Object value1 = PropertyUtils.getSimpleProperty(orig, name);
Object value2 = PropertyUtils.getSimpleProperty(dest, name);
if (value2 != null && !value2.equals(value1)) {
if (PropertyUtils.isReadable(result, name) && PropertyUtils.isWriteable(result, name)) {
BeanUtils.copyProperty(result, name, value2);
}
}
} catch (NoSuchMethodException e) {
}
}
}

}

/**
* 比较一个对象,如是这个对象的某一个属性不为空,把他copy到另一个有这个属性的bean中
*
* @param result 要copy到的bean
* @param orig 原来BEAN
* @throws InvocationTargetException
* @throws IllegalAccessException
*/
public static void copyOrigNotNullPropertyToDestBean(Object result, Object orig) throws IllegalAccessException,
InvocationTargetException {
// Validate existence of the specified beans
if (result == null) {
throw new IllegalArgumentException("No destination bean specified");
}
if (orig == null) {
throw new IllegalArgumentException("No origin bean specified");
}

if (orig instanceof Map) {
throw new IllegalArgumentException("No support map");
}

/* if (orig is a standard JavaBean) */
PropertyDescriptor origDescriptors[] = PropertyUtils.getPropertyDescriptors(orig);
for (int i = 0; i < origDescriptors.length; i++) {
String name = origDescriptors[i].getName();
if ("class".equals(name)) {
continue; // No point in trying to set an object's class
}
if (PropertyUtils.isReadable(orig, name) && PropertyUtils.isWriteable(result, name)) {
try {
Object value1 = PropertyUtils.getSimpleProperty(orig, name);
if (value1 != null) {
if (PropertyUtils.isReadable(result, name) && PropertyUtils.isWriteable(result, name)) {
BeanUtils.copyProperty(result, name, value1);
}
}
} catch (NoSuchMethodException e) {
}
}
}

}
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