Spring提供了一个非常棒的对象复制方法, 其参数的顺序和apache commons提供的同名方法是不一样的, 这个要小心.
源码
public static void copyProperties(Object source, Object target) throws BeansException {
copyProperties(source, target, (Class)null, (String[])null);
} public static void copyProperties(Object source, Object target, Class<?> editable) throws BeansException {
copyProperties(source, target, editable, (String[])null);
} public static void copyProperties(Object source, Object target, String... ignoreProperties) throws BeansException {
copyProperties(source, target, (Class)null, ignoreProperties);
} 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;
} PropertyDescriptor[] targetPds = getPropertyDescriptors(actualEditable);
List ignoreList = ignoreProperties != null?Arrays.asList(ignoreProperties):null;
PropertyDescriptor[] var7 = targetPds;
int var8 = targetPds.length; for(int var9 = 0; var9 < var8; ++var9) {
PropertyDescriptor targetPd = var7[var9];
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 ex = readMethod.invoke(source, new Object[0]);
if(!Modifier.isPublic(writeMethod.getDeclaringClass().getModifiers())) {
writeMethod.setAccessible(true);
} writeMethod.invoke(target, new Object[]{ex});
} catch (Throwable var15) {
throw new FatalBeanException("Could not copy property \'" + targetPd.getName() + "\' from source to target", var15);
}
}
}
}
} }
可以看到, 成员变量赋值是基于目标对象的成员列表, 并且会跳过ignore的以及在源对象中不存在的, 所以这个方法是安全的, 不会因为两个对象之间的结构差异导致错误, 但是必须保证同名的两个成员变量类型相同.