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Java后端接口编写流程

Java后端接口编写流程，更具业务逻辑编写Java后端接口，提供给前端访问

实现逻辑流程

• POJO：实体类编写

@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
@TableName("merchant_mcc")
public class MerchantMcc {/*** null | merchant_mcc.id | @mbg.generated*/@ApiModelProperty("null")@TableIdprivate Long id;/*** MCC字段Code | merchant_mcc.code | @mbg.generated*/@ApiModelProperty("MCC字段Code")private String code;/*** MCC字段Description | merchant_mcc.description | @mbg.generated*/@ApiModelProperty("MCC字段Description")private String description;
}

实体类字段的工具类编写：字段常量编写

package com.wei.gen.po;public class MerchantMccCol {public static final String ID = "id";public static final String CODE = "code";public static final String DESCRIPTION = "description";}

• DAO：数据库访问层编写

public interface MerchantMccRepo extends IService<MerchantMcc> {/*** MCC 根据Code查询Description** @param queryWrapper* @return*/MerchantMcc selectOne(QueryWrapper<MerchantMcc> queryWrapper);}

• 实现类Impl编写

@Slf4j
@Repository
public class MerchantMccRepoImpl extends ServiceImpl<MerchantMccMapper, MerchantMcc> implements MerchantMccRepo {private final MerchantMccMapper merchantMccMapper;public MerchantMccRepoImpl(MerchantMccMapper merchantMccMapper) {this.merchantMccMapper = merchantMccMapper;}@Overridepublic MerchantMcc selectOne(QueryWrapper<MerchantMcc> queryWrapper) {return merchantMccMapper.selectOne(queryWrapper);}
}

Mapper编写：实现对数据库的操作

@Mapper
public interface MerchantMccMapper extends BaseMapper<MerchantMcc> {/*** This method was generated by MyBatis Generator.* This method corresponds to the database table merchant_mcc** @mbg.generated*/MerchantMcc selectByPrimaryKey(Long id);
}

Mapper.xml编写：自定义编写SQL语句，业务逻辑

id属性：指定Mapper.xml文件中的SQL语句对应的Java接口方法名称，这个方法将会执行相应的SQL语句，并返回执行结果

type属性：指定Mapper.xml文件中的Java类对应的实体类名称，这个实体类包含了与SQL语句相对应的属性和方法，用于将执行结果转换为Java对象

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.wei.gen.dao.MerchantMccMapper"></mapper>

Service层：业务逻辑编写

 /*** MCC 根据Code查询Description*/public String getDescriptionByCode(String code) {if (code == null || code.isEmpty()){throw new ManageException("Code不能为空");}MerchantMcc merchantMcc = merchantMccRepo.selectOne(new QueryWrapper<MerchantMcc>().eq("code", code));if (merchantMcc == null) {throw new ManageException("Code不存在");}return merchantMcc.getDescription();}

Controller层：接口编写

@RestController
@Slf4j
@RequestMapping("common")
public class SystemCommonEndpoint {@Resourceprivate CommonService commonService;/*** MCC 根据Code查询Description*/@GetMapping("/search")@ApiOperation("MCC根据Code查询Description")public Result<String> searchDescription(@RequestParam("code") String code) {String description = commonService.getDescriptionByCode(code);return Result.succ(description);}
}

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