org.springframework.beans.BeanUtils的一个demo。可以很优雅的实现将父类字段的值copy到子类中 下面例子的输出结果（子类使用父类的toString方法，有点意思吧）：
true
Person{name='people'}
import org.springframework.beans.BeanUtils;
public class Test {
public static void main(String[] args) {
Person person = new Person("people");
Male male = new Male();
BeanUtils.copyProperties(person, male);
System.out.println(Male.class.isInstance(male));
System.out.println(male);
}
}
class Person {
private String name;
public Person() {
}
public Person(String name) {
this.name = name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public String toString() {
return "Person{" +
"name='" + name + '\'' +
'}';
}
}
class Male extends Person {
private String necklace;
public Male() {
}
public Male(String name) {
super(name);
}
public String getNecklace() {
return necklace;
}
public void setNecklace(String necklace) {
this.necklace = necklace;
}
}
org.springframework.beans.BeanUtils
源码解析：
使用的是反射：
/**
* Copy the property values of the given source bean into the target bean.
* <p>Note: The source and target classes do not have to match or even be derived
* from each other, as long as the properties match. Any bean properties that the
* source bean exposes but the target bean does not will silently be ignored.
* <p>This is just a convenience method. For more complex transfer needs,
* consider using a full BeanWrapper.
* @param source the source bean
* @param target the target bean
* @throws BeansException if the copying failed
* @see BeanWrapper
*/
public static void copyProperties(Object source, Object target) throws BeansException {
copyProperties(source, target, null, (String[]) null);
}
/**
* Copy the property values of the given source bean into the given target bean.
* <p>Note: The source and target classes do not have to match or even be derived
* from each other, as long as the properties match. Any bean properties that the
* source bean exposes but the target bean does not will silently be ignored.
* @param source the source bean
* @param target the target bean
* @param editable the class (or interface) to restrict property setting to
* @param ignoreProperties array of property names to ignore
* @throws BeansException if the copying failed
* @see BeanWrapper
*/
private static void copyProperties(Object source, Object target, Class<?> editable, String... ignoreProperties)
throws BeansException { Assert.notNull(source, "Source must not be null");
Assert.notNull(target, "Target must not be null"); Class<?> actualEditable = target.getClass();
if (editable != null) {
if (!editable.isInstance(target)) {
throw new IllegalArgumentException("Target class [" + target.getClass().getName() +
"] not assignable to Editable class [" + editable.getName() + "]");
}
actualEditable = editable;//如果editable赋值，则ignore Target中的字段属性
}
PropertyDescriptor[] targetPds = getPropertyDescriptors(actualEditable);
List<String> ignoreList = (ignoreProperties != null ? Arrays.asList(ignoreProperties) : null); for (PropertyDescriptor targetPd : targetPds) {
Method writeMethod = targetPd.getWriteMethod();
if (writeMethod != null && (ignoreList == null || !ignoreList.contains(targetPd.getName()))) {
PropertyDescriptor sourcePd = getPropertyDescriptor(source.getClass(), targetPd.getName());
if (sourcePd != null) {
Method readMethod = sourcePd.getReadMethod();
if (readMethod != null &&
ClassUtils.isAssignable(writeMethod.getParameterTypes()[0], readMethod.getReturnType())) {
try {
if (!Modifier.isPublic(readMethod.getDeclaringClass().getModifiers())) {
readMethod.setAccessible(true);
}
Object value = readMethod.invoke(source);
if (!Modifier.isPublic(writeMethod.getDeclaringClass().getModifiers())) {
writeMethod.setAccessible(true);
}
writeMethod.invoke(target, value);
}
catch (Throwable ex) {
throw new FatalBeanException(
"Could not copy property '" + targetPd.getName() + "' from source to target", ex);
}
}
}
}
}
}