背景
Bean的拷贝一直有一些类可以使用,比如Apache的org.apache.commons.beanutils.BeanUtils
或者Spring的org.springframework.beans.BeanUtils
。
根据定义的白名单字段进行Bean的拷贝
我需要一个只拷贝我指定的字段的Bean拷贝,而Spring的org.springframework.beans.BeanUtils
提供如下几个方法:
其中第2、3个是可以指定属性的,第2个指定可以通过Class指定,基本满足我的需求;第3个指定无须理会的字段。
我不想定义另外的类,或者另外的父类去指定部分属性,我想通过自己配置的白名单只拷贝白名单指定的属性:
package com.nicchagil.exercise.springbootexercise.util;
import java.beans.PropertyDescriptor;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.springframework.beans.BeanUtils;
public class BeanCopyUtils {
/**
* 根据白名单字段拷贝Bean
*/
public static <T> T copyProperties(Object source, Class<T> clazz, String[] whiteProperties) {
List<String> ignorePropertiesList = BeanCopyUtils.getIgnoreProperties(clazz, whiteProperties);
String[] ignoreProperties = new String[ignorePropertiesList.size()];
ignorePropertiesList.toArray(ignoreProperties);
T target;
try {
target = clazz.newInstance();
} catch (InstantiationException | IllegalAccessException e) {
throw new RuntimeException("通过Class实例化对象发生异常", e);
}
BeanUtils.copyProperties(source, target, ignoreProperties);
return target;
}
/**
* 根据白名单字段字段获取无须理会的字段
* @param clazz
* @param whiteProperties
* @return
*/
public static List<String> getIgnoreProperties(Class<?> clazz, String[] whiteProperties) {
List<String> allProperties = BeanCopyUtils.getAllProperties(clazz);
if (allProperties == null || allProperties.size() == 0) {
return null;
}
allProperties.removeAll(Arrays.asList(whiteProperties));
return allProperties;
}
/**
* 获取全部属性名称
*/
public static List<String> getAllProperties(Class<?> clazz) {
PropertyDescriptor[] propertyDescriptors = BeanUtils.getPropertyDescriptors(clazz);
if (propertyDescriptors == null || propertyDescriptors.length == 0) {
return null;
}
List<String> properties = new ArrayList<String>();
for (PropertyDescriptor propertyDescriptor : propertyDescriptors) {
properties.add(propertyDescriptor.getName());
}
return properties;
}
}
单元测试:
package com.nicchagil.exercise.springbootexercise;
import org.junit.Test;
import com.nicchagil.exercise.springbootexercise.util.BeanCopyUtils;
public class BeanCopyUtilsTest {
@Test
public void test() {
User user = new User();
user.setId(123);
user.setName("Nick Huang");
User userCopy = BeanCopyUtils.copyProperties(user, User.class, new String[] {"name"});
System.out.println("user : " + user);
System.out.println("userCopy : " + userCopy);
}
public static class User {
private Integer id;
private String name;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public String toString() {
return "User [id=" + id + ", name=" + name + "]";
}
}
}