import org.springframework.beans.BeanUtils;
BeanUtils.copyProperties(origin, target);

import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ObjectReader;
import com.jd.fastjson.JSON;
ObjectMapper objectMapper = new ObjectMapper();
//配置該objectMapper在反序列化時(shí)，忽略目標(biāo)對(duì)象沒有的屬性。凡是使用該objectMapper反序列化時(shí)，都會(huì)擁有該特性。
objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
//讀入需要更新的目標(biāo)實(shí)體
ObjectReader objectReader = objectMapper.readerForUpdating(target);
//將源實(shí)體的值賦值到目標(biāo)實(shí)體上
objectReader.readValue(JSON.toJSONString(source));

 /*
 通過該方法對(duì)mapper對(duì)象進(jìn)行設(shè)置，所有序列化的對(duì)象都將按改規(guī)則進(jìn)行系列化
 Include.Include.ALWAYS 默認(rèn)
 Include.NON_DEFAULT 屬性為默認(rèn)值不序列化
 Include.NON_EMPTY 屬性為 空（“”） 或者為 NULL 都不序列化
 Include.NON_NULL 屬性為NULL 不序列化
 */
  objectMapper.setSerializationInclusion(JsonInclude.Include.NON_DEFAULT);
  String outJson = objectMapper.writeValueAsString(productDetail);
//上面代碼里，outJson的值將會(huì)過濾掉只有默認(rèn)值的屬性

 @RequestMapping(value = "/{id}", method = RequestMethod.PUT)
 public HttpEntity update(@PathVariable int id, @RequestBody ProductDetail productDetail)
   throws IOException {
  ProductDetail existing = repository.findById(id).get();
  objectMapper.setSerializationInclusion(JsonInclude.Include.NON_DEFAULT);
  String outJson = objectMapper.writeValueAsString(productDetail);
  ObjectReader objectReader = objectMapper.readerForUpdating(existing);
  objectReader.readValue(outJson);
  repository.save(existing);
  return new ResponseEntity<>(existing, HttpStatus.ACCEPTED);
 }