动态更新非null字段

[zhangzhenhuajack]

只更新非null字段

/**

 * @param user

 * @return

 */

@PostMapping("/user/notnull")

public User saveUserNotNullProperties(@RequestBody User user) {

   //数据库里面取出最新的数据，当然了这一步严谨一点可以根据id和version来取数据，如果没取到可以报乐观锁异常

   User userSrc = userRepository.findById(user.getId()).get();

   //将不是null的字段copy到userSrc里面，我们只更新传递了不是null的字段

   PropertyUtils.copyNotNullProperty(user,userSrc);

   return userRepository.save(userSrc);

}

package com.example.jpa.example1.util;



import com.google.common.collect.Sets;

import org.springframework.beans.BeanUtils;

import org.springframework.beans.BeanWrapper;

import org.springframework.beans.BeanWrapperImpl;



import java.util.Set;



public class PropertyUtils {



    /**

     * 只copy非null字段

     *

     * @param source

     * @param dest

     */

    public static void copyNotNullProperty(Object source, Object dest) {

        //利用spring提供的工具类忽略为null的字段

        BeanUtils.copyProperties(source, dest, getNullPropertyNames(source));

    }



    /**

     * get property name that value is null

     *

     * @param source

     * @return

     */

    private static String[] getNullPropertyNames(Object source) {

        final BeanWrapper src = new BeanWrapperImpl(source);

        java.beans.PropertyDescriptor[] pds = src.getPropertyDescriptors();



        Set<String> emptyNames = Sets.newHashSet();

        for (java.beans.PropertyDescriptor pd : pds) {

            Object srcValue = src.getPropertyValue(pd.getName());

            if (srcValue == null) {

                emptyNames.add(pd.getName());

            }

        }

        String[] result = new String[emptyNames.size()];

        return emptyNames.toArray(result);

    }

}