实体类与String相互转换

在工作中偶然遇到需要将实体类与String互转的情况，简单记录一下

准备一个实体类 

@ApiModel(description = "满减类型配置")
@Data
public class DiscountTypeConfig {
    /**
     * 满几件
     */
    @ApiModelProperty(name = "full_goods_num", value = "满几件", required = true)
    @NotNull(message = "满几件不能为空")
    @Range(min = 1, message = "满几件必须大于0")
    private Integer fullGoodsNum;

    /**
     * 打几折（百分比）
     */
    @ApiModelProperty(name = "percentage_discount", value = "打几折（百分比）", required = true)
    @NotNull(message = "打几折（百分比）不能为空")
    @Range(min = 1, max = 99, message = "打几折（百分比）必须大于0小于100")
    private Integer percentageDiscount;

准备json工具类

package com.kaying.star.system.common.util.json;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import java.util.List;
import java.util.Map;

/**
 * json工具类
 *
 */
@Component
public class JsonUtils {
    @Autowired
    private ObjectMapper objectMapper;

    public String bean2Json(Object data) {
        try {
            String result = objectMapper.writeValueAsString(data);
            return result;
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
        return null;
    }

    public  T json2Bean(String jsonData, Class beanType) {
        try {
            T result = objectMapper.readValue(jsonData, beanType);
            return result;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public  List json2List(String jsonData, Class beanType) {
        JavaType javaType = objectMapper.getTypeFactory().constructParametricType(List.class, beanType);
        try {
            List resultList = objectMapper.readValue(jsonData, javaType);
            return resultList;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public  Map json2Map(String jsonData, Class keyType, Class valueType) {
        JavaType javaType = objectMapper.getTypeFactory().constructMapType(Map.class, keyType, valueType);
        try {
            Map resultMap = objectMapper.readValue(jsonData, javaType);
            return resultMap;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
}

转成string之后可以保存至数据库

String disConfig = jsonUtils.bean2Json(discountTypeConfig)

从数据库中取出String字段，将String转成实体类

//通过实体类转成的string 
String disConfig = jsonUtils.bean2Json(discountTypeConfig)

//通过工具类将string转换成实体类
DiscountTypeConfig discountTypeConfig = jsonUtils.json2Bean(disConfig , DiscountTypeConfig.class)

适用于各种不同的配置等使用场景，将实体类转成string存入数据库，将string取出转成实体类！