三种复制属性的工具
1.cglib
import net.sf.cglib.beans.BeanCopier;
BeanCopier copier = BeanCopier.create(User.class, User.class, false);
copier.copy(source, user, null);
2.org.apache.commons
import org.apache.commons.beanutils.BeanUtils; BeanUtils.copyProperties(user, source);
3.spring beans
org.springframework.beans.BeanUtils.copyProperties(source, user);
效率方面:
spring beans>=cglib>org.apache.commons.beanutils.BeanUtils
org.springframework.beans.BeanUtils与net.sf.cglib.beans.BeanCopier
在同一个数量级,区别不大,比org.apache.commons.beanutils.BeanUtils效率快一个数量级.
org.springframework.beans.BeanUtils.copyProperties最终调用的是以下这个方法.
/**
* 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;
}
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);
}
}
}
}
}
}
之前以为bean中有bean或List的会递归调用,实际上并没有.用反射调用read method和write method.