前言
mysql5.7版本之后,列值的类型支持json格式,那么如何将json格式的字段类型的值映射到java对象当中呢?以下记录一下转换方法.
数据库展示:
specs列为json格式,现将此列的值映射到java的对象的属性当中
public class Spec implements Serializable {
private Integer key_id;
private String key;
private Integer value_id;
private String value;
}
创建Pojo对象
@Entity
@Table(name = "sku")
@Getter
@Setter
public class SkuEntity extends BaseEntity {
@Id
private int id;
private BigDecimal price;
private BigDecimal discountPrice;
private byte online;
private String img;
private String title;
private int spuId;
//private List<Spec>specs;
private String specs;
private String code;
private int stock;
private Integer categoryId;
private Integer rootCategoryId;
GenericAndJson工具类代码:
package com.my.sevencell.api.utils;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.my.sevencell.api.exception.http.ServerErrorException;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import java.io.IOException;
/**
* @Description: 此工具类进行json的序列化和反序列化
* @Author: my
* @CreateDate: 2020/3/5 22:08
* @UpdateUser:
* @UpdateDate: 2020/3/5 22:08
* @UpdateRemark: 修改内容
* @Version: 1.0
*/
@Component
@Slf4j
public class GenericAndJson {
private static ObjectMapper mapper;
/**
* 采用set方法自动注入
* @param mapper
*/
@Autowired
public void setMapper(ObjectMapper mapper) {
GenericAndJson.mapper = mapper;
}
public static<T> String objectToJson(T o){
try {
String jsonString = mapper.writeValueAsString(o);
return jsonString;
} catch (JsonProcessingException e) {
log.error(e.getMessage());
throw new ServerErrorException(9999);
}
}
public static<T> T jsonToObject(String json, TypeReference<T>typeReference){
try {
if (json.isEmpty()){
return null;
}
T t = mapper.readValue(json, typeReference);
return t;
} catch (IOException e) {
log.error(e.getMessage());
throw new ServerErrorException(9999);
}
}
}
方法一
1.我们将specs列的值当做String类型进行接收
private String specs;
2.编写specs的get/set方法,通过GenericAndJson工具类进行序列化和烦序列化
public List<SpecVO> getSpecs() {
if(this.specs.isEmpty()){
return Collections.emptyList();
}
List<SpecVO> specs = GenericAndJson.jsonToObject(this.specs, new TypeReference<List<SpecVO>>() {
});
return specs;
}
public void setSpecs(List<SpecVO> specs) {
String json = GenericAndJson.objectToJson(specs);
this.specs = json;
}
测试结果:
{
"id": 1,
"price": 3999.00,
"discount_price": null,
"online": 1,
"img": "http://xxxxx",
"title": "复古双色沙发(藏青色)",
"spu_id": 1,
"specs": [
{
"key_id": 1,
"key": "颜色",
"value_id": 2,
"value": "藏青色"
},
{
"key_id": 7,
"key": "双色沙发尺寸(非标)",
"value_id": 32,
"value": "1.5米 x 1米"
}
],
"code": "1$1-2#7-32",
"stock": 89,
"category_id": 35,
"root_category_id": null
}
方法二
1.新建工具类ConveterObjectAndJson,实现AttributeConverter接口
package com.my.sevencell.api.utils;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.my.sevencell.api.exception.http.ServerErrorException;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import javax.persistence.AttributeConverter;
import java.io.IOException;
/**
* @Description: 实现json的序列化和反序列化,只需要对需要转换的
* 属性打上@convet主机即可
* @Author: my
* @CreateDate: 2020/3/6 9:32
* @UpdateUser:
* @UpdateDate: 2020/3/6 9:32
* @UpdateRemark: 修改内容
* @Version: 1.0
*/
@Slf4j
public class ConveterObjectAndJson<T> implements AttributeConverter<T,String> {
@Autowired
private ObjectMapper objectMapper;
@Override
public String convertToDatabaseColumn(T t) {
try {
String jsonString = objectMapper.writeValueAsString(t);
return jsonString;
} catch (JsonProcessingException e) {
log.error(e.getMessage());
throw new ServerErrorException(9999);
}
}
@Override
public T convertToEntityAttribute(String s) {
try {
if(s.isEmpty()){
return null;
}
T t = objectMapper.readValue(s, new TypeReference<T>() {
});
return t;
} catch (IOException e) {
log.error(e.getMessage());
throw new ServerErrorException(9999);
}
}
}
2.我们将specs列的值当用List集合进行接收,并打上@Convert(converter = ConveterObjectAndJson.class)的注解
注意:
1.specs属性的get/set方法可自动生成,无需进行任何改动.
2.用List<specVo>接收时,idea会报错,不过不影响正常运行,可忽略
3.@Conver是avax.persistence包下的;
@Convert(converter = ConveterObjectAndJson.class)
private List<SpecVO> specs;
测试结果:
{
"id": 1,
"price": 3999.00,
"discount_price": null,
"online": 1,
"img": "http://xxxx",
"title": "复古双色沙发(藏青色)",
"spu_id": 1,
"specs": [
{
"key": "颜色",
"value": "藏青色",
"key_id": 1,
"value_id": 2
},
{
"key": "双色沙发尺寸(非标)",
"value": "1.5米 x 1米",
"key_id": 7,
"value_id": 32
}
],
"code": "1$1-2#7-32",
"stock": 89,
"category_id": 35,
"root_category_id": null
}