Springboot-数据的返回

2021-02-19 MarsHu springboot springboot

---

• Jaskson序列化库的重要配置
• 对Banner资源进行null值判断
• DozerBeanMapper拷贝属性
• 使用Pageable分页,自定义分页结果集
• 无限级分类表设计,路径表达法
• 通过分类id查找对应的Spu
• @Validated验证信息的配置
• Optional的使用

Jaskson序列化库的重要配置

通过前面的步骤,我们可以通过PostMan发送请求,拿回数据。通过访问:localhost:8080/v1/banner/name/b-1,拿回以下数据。

{
    "createTime": null,
    "updateTime": null,
    "deleteTime": null,
    "id": 1,
    "name": "b-1",
    "description": "首页顶部主banner",
    "title": null,
    "img": "http://xxx.xxx.xxx/d87e180f-0f8a-480c-966a-f2f487b801cc.png",
    "items": [
        {
            "createTime": null,
            "updateTime": null,
            "deleteTime": null,
            "id": 12,
            "img": "http://xxx.xxx.xxx/m1.png",
            "keyword": "t-2",
            "type": 3,
            "bannerId": 1,
            "name": null
        },
        {
            "createTime": null,
            "updateTime": null,
            "deleteTime": null,
            "id": 13,
            "img": "http://xxx.xxx.xxx/assets/702f2ce9-5729-4aa4-aeb3-921513327747.pn",
            "keyword": "23",
            "type": 1,
            "bannerId": 1,
            "name": null
        },
        {
            "createTime": null,
            "updateTime": null,
            "deleteTime": null,
            "id": 14,
            "img": "http://xxx.xxx.xxx/assets/b8e510a1-8340-43c2-a4b0-0e56a40256f9.png",
            "keyword": "24",
            "type": 1,
            "bannerId": 1,
            "name": null
        }
    ]
}

springboot默认使用json库是jackson,观察返回结果,我们可以发现一下问题:首先数据库中createTime等time字段是有值的,但是前端返回数据中没有值.其次,数据库中createTime字段为create_time,而前端返回的数据字段为createTime。

关于createTime字段没有值的问题,是因为我们提取了积累BaseEntity.我们需要在基类上使用注解@MappedSuperclass

package com.zhqx.missyou.model;

import lombok.Getter;
import lombok.Setter;

import javax.persistence.MappedSuperclass;
import java.util.Date;

@Getter
@Setter
@MappedSuperclass
public abstract class BaseEntity {
    private Date createTime;
    private Date updateTime;
    private Date deleteTime;
}

再次请求时,就能得到日期字段的值了。如果需要将返回字段createTime改为create_time,我们可以修改application.yml文件

spring:
  profiles:
    active: dev
  jpa:
    hibernate:
      ddl-auto: none
  jackson:
    property-naming-strategy: SNAKE_CASE

zhqx:
  api-package: com.zhqx.missyou.api

再次请求时,createTime就变成了create_time。此时的日期数据如下:

"create_time": "2019-07-27T20:47:15.000+00:00",

这个时候返回的日期格式为标准日期格式,假如我们只想返回时间戳日期格式,可在application.yml文件中配置如下:

spring:
  profiles:
    active: dev
  jpa:
    hibernate:
      ddl-auto: none
  jackson:
    property-naming-strategy: SNAKE_CASE
    serialization:
      WRITE_DATES_AS_TIMESTAMPS: true

zhqx:
  api-package: com.zhqx.missyou.api

再次请求时,就能得到时间戳格式的日期字段:

"create_time": 1564260435000,

如果,我们不希望前端返回的json数据中有相关日期字段,我们可以进行如下设置:

package com.zhqx.missyou.model;

import com.fasterxml.jackson.annotation.JsonIgnore;
import lombok.Getter;
import lombok.Setter;

import javax.persistence.MappedSuperclass;
import java.util.Date;

@Getter
@Setter
@MappedSuperclass
public abstract class BaseEntity {

    @JsonIgnore
    private Date createTime;
    @JsonIgnore
    private Date updateTime;
    @JsonIgnore
    private Date deleteTime;
}

再次请求时,我们可以得到如下请求内容:

{
    "id": 1,
    "name": "b-1",
    "description": "首页顶部主banner",
    "title": null,
    "img": "http://xxx.xxx.xxx/d87e180f-0f8a-480c-966a-f2f487b801cc.png",
    "items": [
        {
            "id": 12,
            "img": "http://xxx.xxx.xxx/m1.png",
            "keyword": "t-2",
            "type": 3,
            "banner_id": 1,
            "name": null
        },
        {
            "id": 13,
            "img": "http://xxx.xxx.xxx/assets/702f2ce9-5729-4aa4-aeb3-921513327747.pn",
            "keyword": "23",
            "type": 1,
            "banner_id": 1,
            "name": null
        },
        {
            "id": 14,
            "img": "http://xxx.xxx.xxx/assets/b8e510a1-8340-43c2-a4b0-0e56a40256f9.png",
            "keyword": "24",
            "type": 1,
            "banner_id": 1,
            "name": null
        }
    ]
}

对Banner资源进行null值判断

BannerController类的修改

package com.zhqx.missyou.api.v1;

import com.zhqx.missyou.exception.http.NotFoundException;
import com.zhqx.missyou.model.Banner;
import com.zhqx.missyou.service.BannerService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.*;

import javax.validation.constraints.NotBlank;

@RestController
@RequestMapping("/banner")
@Validated
public class BannerController {

    @Autowired
    private BannerService bannerService;

    @GetMapping("/name/{name}")
    public Banner getByName(@PathVariable @NotBlank String name) {
        Banner banner = bannerService.getByName(name);
        if (banner == null) {
            throw new NotFoundException(30005);
        }
        return banner;
    }
}

在exception-code.properties配置文件中新增错误信息配置。

zhqx.codes[10000]= 通用异常
zhqx.codes[10001]= 通用参数异常

zhqx.codes[30005]= Banner类的资源不存在

DozerBeanMapper拷贝属性

传统的BeanUtils工具类拷贝不能够进行深拷贝,即假如目标对象中有对象类型数据时,使用该工具会有问题(未验证!) 引入相关Jar包

<dependency>
    <groupId>com.github.dozermapper</groupId>
    <artifactId>dozer-core</artifactId>
    <version>6.5.0</version>
</dependency>

Spu类:

package com.zhqx.missyou.model;

import lombok.Getter;
import lombok.Setter;

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import java.util.List;

@Getter
@Setter
@Entity
public class Spu extends BaseEntity {
    @Id
    private Long id;
    private String title;
    private String subtitle;
    private Long categoryId;
    private Long rootCategoryId;
    private Boolean online;
    private String price;
    private Long sketchSpecId;
    private Long defaultSkuId;
    private String img;
    private String discountPrice;
    private String description;
    private String tags;
    private Boolean isTest;
    //private Object spuThemeImg;
    private String forThemeImg;

    @OneToMany
    @JoinColumn(name = "spuId")
    private List<Sku> skuList;

    @OneToMany
    @JoinColumn(name = "spuId")
    private List<SpuImg> spuImgList;

    @OneToMany
    @JoinColumn(name = "spuId")
    private List<SpuDetailImg> spuDetailImgList;
}

Sku类:

package com.zhqx.missyou.model;

import lombok.Getter;
import lombok.Setter;

import javax.persistence.Entity;
import javax.persistence.Id;
import java.math.BigDecimal;

@Getter
@Setter
@Entity
public class Sku extends BaseEntity {
    @Id
    private Long id;
    private BigDecimal price;
    private BigDecimal discountPrice;
    private Boolean online;
    private String img;
    private String title;
    private Long spuId;

    private String specs;
    private String code;
    private Long stock;
    private Long categoryId;
    private Long rootCategoryId;

}

SpuDetailImg类:

package com.zhqx.missyou.model;

import lombok.Getter;
import lombok.Setter;

import javax.persistence.*;

@Getter
@Setter
@Entity
public class SpuDetailImg extends BaseEntity {
    @Id
    private Long id;
    private String img;
    private Long spuId;
    private Long index;

}

SpuImg类:

package com.zhqx.missyou.model;

import lombok.Getter;
import lombok.Setter;

import javax.persistence.*;
import java.sql.Timestamp;
import java.util.Objects;

@Getter
@Setter
@Entity
public class SpuImg extends BaseEntity {
    @Id
    private Long id;
    private String img;
    private Long spuId;

}

SpuRepository类:

package com.zhqx.missyou.repository;

import com.zhqx.missyou.model.Spu;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface SpuRepository extends JpaRepository<Spu, Long> {
    Spu findOneById(Long id);
}

SpuServiceImpl类:

package com.zhqx.missyou.service.impl;

import com.zhqx.missyou.model.Spu;
import com.zhqx.missyou.repository.SpuRepository;
import com.zhqx.missyou.service.SpuService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class SpuServiceImpl implements SpuService {

    @Autowired
    private SpuRepository spuRepository;

    @Override
    public Spu getSpu(Long id) {
        return spuRepository.findOneById(id);
    }

    @Override
    public List<Spu> getLatestPagingSpu() {
        return spuRepository.findAll();
    }
}

SpuController类:

package com.zhqx.missyou.api.v1;

import com.github.dozermapper.core.DozerBeanMapperBuilder;
import com.github.dozermapper.core.Mapper;
import com.zhqx.missyou.exception.http.NotFoundException;
import com.zhqx.missyou.model.Spu;
import com.zhqx.missyou.service.SpuService;
import com.zhqx.missyou.vo.SpuSimplifyVO;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.validation.constraints.Positive;
import java.util.ArrayList;
import java.util.List;

@RestController
@RequestMapping("/spu")
@Validated
public class SpuController {

    @Autowired
    private SpuService spuService;

    @GetMapping("/id/{id}/detail")//@Positive整数
    public Spu getDetail(@PathVariable @Positive Long id) {
        Spu spu = spuService.getSpu(id);
        if(spu == null) {
            throw new NotFoundException(30003);
        }
        return spu;
    }

    @GetMapping("/id/{id}/simplify")
    public SpuSimplifyVO getSimplifyVO(@PathVariable @Positive Long id) {
        Spu spu = spuService.getSpu(id);
        SpuSimplifyVO vo = new SpuSimplifyVO();
        BeanUtils.copyProperties(spu, vo);
        return vo;
    }

    @GetMapping("/latest")
    public List<SpuSimplifyVO> getLatestSpuList() {
        Mapper mapper = DozerBeanMapperBuilder.buildDefault();
        List<Spu> spuList = spuService.getLatestPagingSpu();
        List<SpuSimplifyVO> vos = new ArrayList<>();
        spuList.forEach(spu -> {
            SpuSimplifyVO vo = mapper.map(spu, SpuSimplifyVO.class);
            vos.add(vo);
        });

        return vos;
    }
}

使用Pageable分页,自定义分页结果集

修改SpuServiceImpl方法,将分页查询结果返回封装到Page对象

package com.zhqx.missyou.service.impl;

import com.zhqx.missyou.model.Spu;
import com.zhqx.missyou.repository.SpuRepository;
import com.zhqx.missyou.service.SpuService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort;
import org.springframework.stereotype.Service;

@Service
public class SpuServiceImpl implements SpuService {

    @Autowired
    private SpuRepository spuRepository;

    @Override
    public Spu getSpu(Long id) {
        return spuRepository.findOneById(id);
    }

    @Override
    public Page<Spu> getLatestPagingSpu(Integer pageNum, Integer size) {
        //这里的排序字段对应的应该是实体中的属性,而不是数据库中的字段
        Pageable pageable = PageRequest.of(pageNum, size, Sort.by("createTime").descending());
        return spuRepository.findAll(pageable);
    }
}

定义分页实体PageCounter,包含page属性和count属性:

package com.zhqx.missyou.bo;

import lombok.Getter;
import lombok.Setter;

@Getter
@Setter
public class PageCounter {
    private Integer page;
    private Integer count;
}

定义工具类,用来将前端传递的start参数和count参数封装到对象PageCounter中

package com.zhqx.missyou.util;

import com.zhqx.missyou.bo.PageCounter;

public class CommonUtil {

    //start:第几条数据开始查询,count:查询多少条数据
    public static PageCounter convertToPageParameter(Integer start, Integer count) {
        //当前页码
        int pageNum = start/count;
        PageCounter pageCounter = new PageCounter();
        pageCounter.setPage(pageNum);
        pageCounter.setCount(count);
        return pageCounter;
    }
}

定义分页数据对象Paging,包含分页信息以及数据信息

package com.zhqx.missyou.vo;

import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;
import org.springframework.data.domain.Page;

import java.util.List;

@Getter
@Setter
@NoArgsConstructor
public class Paging<T> {
    //总数
    private Long total;
    //页面显示数
    private Integer count;
    //当前页
    private Integer page;
    //总页数
    private Integer totalPage;
    private List<T> items;

    public Paging(Page<T> pageT) {
        this.initPageParameters(pageT);
        this.items = pageT.getContent();
    }

    void initPageParameters(Page<T> pageT) {
        this.total = pageT.getTotalElements();
        this.count = pageT.getSize();
        this.page = pageT.getNumber();
        this.totalPage = pageT.getTotalPages();
    }
}

定义类PagingDozer,将原始的Page数据中返回的集合数据进行属性的舍弃,封装到新的返回数据对象中,将整个数据的拷贝放到此类中完成

package com.zhqx.missyou.vo;

import com.github.dozermapper.core.DozerBeanMapperBuilder;
import com.github.dozermapper.core.Mapper;
import org.springframework.data.domain.Page;

import java.util.ArrayList;
import java.util.List;

//T:源数据类型;K:目标数据类型
public class PagingDozer<T, K> extends Paging {

    //kClass:目标数据类型
    public PagingDozer(Page<T> pageT, Class<K> kClass) {
        this.initPageParameters(pageT);

        List<T> tList = pageT.getContent();
        Mapper mapper = DozerBeanMapperBuilder.buildDefault();

        List<K> voList = new ArrayList<>();

        tList.forEach(t -> {
            K vo = mapper.map(t, kClass);
            voList.add(vo);
        });
        this.setItems(voList);
    }
}

修改SpuController类:

package com.zhqx.missyou.api.v1;

import com.zhqx.missyou.bo.PageCounter;
import com.zhqx.missyou.exception.http.NotFoundException;
import com.zhqx.missyou.model.Spu;
import com.zhqx.missyou.service.SpuService;
import com.zhqx.missyou.util.CommonUtil;
import com.zhqx.missyou.vo.PagingDozer;
import com.zhqx.missyou.vo.SpuSimplifyVO;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.*;

import javax.validation.constraints.Positive;

@RestController
@RequestMapping("/spu")
@Validated
public class SpuController {

    @Autowired
    private SpuService spuService;

    @GetMapping("/id/{id}/detail")//@Positive整数
    public Spu getDetail(@PathVariable @Positive Long id) {
        Spu spu = spuService.getSpu(id);
        if(spu == null) {
            throw new NotFoundException(30003);
        }
        return spu;
    }

    @GetMapping("/id/{id}/simplify")
    public SpuSimplifyVO getSimplifyVO(@PathVariable @Positive Long id) {
        Spu spu = spuService.getSpu(id);
        SpuSimplifyVO vo = new SpuSimplifyVO();
        BeanUtils.copyProperties(spu, vo);
        return vo;
    }

    @GetMapping("/latest")
    public PagingDozer<Spu, SpuSimplifyVO> getLatestSpuList(@RequestParam(defaultValue = "0") Integer start,
                                                @RequestParam(defaultValue = "10") Integer count) {
        PageCounter pageCounter = CommonUtil.convertToPageParameter(start, count);
        Page<Spu> page = spuService.getLatestPagingSpu(pageCounter.getPage(), pageCounter.getCount());
        return new PagingDozer<>(page, SpuSimplifyVO.class);

    }
}

无限级分类表设计,路径表达法

传统的分类中,对于分类节点,我们通常都是采取parent_id字段来表示,但是这种方式对于多级分类来说,回溯查询效率比较低下。我们可以采取设计一个字段path,在path字段中,保存从根节点开始到当前节点的id路径。

通过分类id查找对应的Spu

SpuRepository类:

package com.zhqx.missyou.repository;

import com.zhqx.missyou.model.Spu;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface SpuRepository extends JpaRepository<Spu, Long> {
    Spu findOneById(Long id);

    Page<Spu> findByCategoryIdOOrderByCreateTimeDesc(Long cid, Pageable pageable);

    Page<Spu> findByRootCategoryIdOrderBOrderByCreateTimeDesc(Long cid, Pageable pageable);
}

SpuServiceImpl类:

package com.zhqx.missyou.service.impl;

import com.zhqx.missyou.model.Spu;
import com.zhqx.missyou.repository.SpuRepository;
import com.zhqx.missyou.service.SpuService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort;
import org.springframework.stereotype.Service;

@Service
public class SpuServiceImpl implements SpuService {

    @Autowired
    private SpuRepository spuRepository;

    @Override
    public Spu getSpu(Long id) {
        return spuRepository.findOneById(id);
    }

    @Override
    public Page<Spu> getLatestPagingSpu(Integer pageNum, Integer size) {
        //这里的排序字段对应的应该是实体中的属性,而不是数据库中的字段
        Pageable pageable = PageRequest.of(pageNum, size, Sort.by("createTime").descending());
        return spuRepository.findAll(pageable);
    }

    @Override
    public Page<Spu> getByCategory(Long cid, Boolean isRoot, Integer pageNum, Integer size) {
        Pageable pageable = PageRequest.of(pageNum, size);
        if (isRoot) {
            return spuRepository.findByRootCategoryIdOrderBOrderByCreateTimeDesc(cid, pageable);
        }
        return spuRepository.findByCategoryIdOOrderByCreateTimeDesc(cid, pageable);
    }
}

SpuController类:

package com.zhqx.missyou.api.v1;

import com.zhqx.missyou.bo.PageCounter;
import com.zhqx.missyou.exception.http.NotFoundException;
import com.zhqx.missyou.model.Spu;
import com.zhqx.missyou.service.SpuService;
import com.zhqx.missyou.util.CommonUtil;
import com.zhqx.missyou.vo.PagingDozer;
import com.zhqx.missyou.vo.SpuSimplifyVO;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.*;

import javax.validation.constraints.Positive;

@RestController
@RequestMapping("/spu")
@Validated
public class SpuController {

    @Autowired
    private SpuService spuService;

    @GetMapping("/id/{id}/detail")//@Positive整数
    public Spu getDetail(@PathVariable @Positive Long id) {
        Spu spu = spuService.getSpu(id);
        if(spu == null) {
            throw new NotFoundException(30003);
        }
        return spu;
    }

    @GetMapping("/id/{id}/simplify")
    public SpuSimplifyVO getSimplifyVO(@PathVariable @Positive Long id) {
        Spu spu = spuService.getSpu(id);
        SpuSimplifyVO vo = new SpuSimplifyVO();
        BeanUtils.copyProperties(spu, vo);
        return vo;
    }

    @GetMapping("/latest")
    public PagingDozer<Spu, SpuSimplifyVO> getLatestSpuList(@RequestParam(defaultValue = "0") Integer start,
                                                @RequestParam(defaultValue = "10") Integer count) {
        PageCounter pageCounter = CommonUtil.convertToPageParameter(start, count);
        Page<Spu> page = spuService.getLatestPagingSpu(pageCounter.getPage(), pageCounter.getCount());
        return new PagingDozer<>(page, SpuSimplifyVO.class);

    }

    @GetMapping("/by/category/{id}")
    public PagingDozer<Spu, SpuSimplifyVO> getByCategoryId(@PathVariable @Positive Long id,
                                                           @RequestParam(name = "is_root", defaultValue = "false") Boolean isRoot,
                                                           @RequestParam(defaultValue = "0") Integer start,
                                                           @RequestParam(defaultValue = "10") Integer count) {
        PageCounter pageCounter = CommonUtil.convertToPageParameter(start, count);
        Page<Spu> page = spuService.getByCategory(id, isRoot, pageCounter.getPage(), pageCounter.getCount());
        return new PagingDozer<>(page, SpuSimplifyVO.class);
    }
}

@Validated验证信息的配置

在resources目录下新建配置文件名为ValidationMessages.properties(固定名称)

id.positive = id必须是正整数

在SpuController中配置验证错误信息

package com.zhqx.missyou.api.v1;

import com.zhqx.missyou.bo.PageCounter;
import com.zhqx.missyou.exception.http.NotFoundException;
import com.zhqx.missyou.model.Spu;
import com.zhqx.missyou.service.SpuService;
import com.zhqx.missyou.util.CommonUtil;
import com.zhqx.missyou.vo.PagingDozer;
import com.zhqx.missyou.vo.SpuSimplifyVO;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.*;

import javax.validation.constraints.Positive;

@RestController
@RequestMapping("/spu")
@Validated
public class SpuController {

    @Autowired
    private SpuService spuService;

    @GetMapping("/id/{id}/detail")//@Positive整数
    public Spu getDetail(@PathVariable @Positive(message = "{id.positive}") Long id) {
        Spu spu = spuService.getSpu(id);
        if(spu == null) {
            throw new NotFoundException(30003);
        }
        return spu;
    }

    @GetMapping("/id/{id}/simplify")
    public SpuSimplifyVO getSimplifyVO(@PathVariable @Positive(message = "{id.positive}") Long id) {
        Spu spu = spuService.getSpu(id);
        SpuSimplifyVO vo = new SpuSimplifyVO();
        BeanUtils.copyProperties(spu, vo);
        return vo;
    }

    @GetMapping("/latest")
    public PagingDozer<Spu, SpuSimplifyVO> getLatestSpuList(@RequestParam(defaultValue = "0") Integer start,
                                                @RequestParam(defaultValue = "10") Integer count) {
        PageCounter pageCounter = CommonUtil.convertToPageParameter(start, count);
        Page<Spu> page = spuService.getLatestPagingSpu(pageCounter.getPage(), pageCounter.getCount());
        return new PagingDozer<>(page, SpuSimplifyVO.class);

    }

    @GetMapping("/by/category/{id}")
    public PagingDozer<Spu, SpuSimplifyVO> getByCategoryId(@PathVariable @Positive(message = "{id.positive}") Long id,
                                                           @RequestParam(name = "is_root", defaultValue = "false") Boolean isRoot,
                                                           @RequestParam(defaultValue = "0") Integer start,
                                                           @RequestParam(defaultValue = "10") Integer count) {
        PageCounter pageCounter = CommonUtil.convertToPageParameter(start, count);
        Page<Spu> page = spuService.getByCategory(id, isRoot, pageCounter.getPage(), pageCounter.getCount());
        return new PagingDozer<>(page, SpuSimplifyVO.class);
    }
}

Optional的使用

使用Optional代替原本直接返回对象的模式:

package com.zhqx.missyou.repository;

import com.zhqx.missyou.model.Theme;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;
import org.springframework.stereotype.Repository;

import java.util.List;
import java.util.Optional;

@Repository
public interface ThemeRepository extends JpaRepository<Theme, Long> {

    @Query("select t from Theme t where t.name in (:names)")
    List<Theme> findByNames(@Param("names") List<String> names);

    //代替方法:Theme findByName(String name);
    Optional<Theme> findByName(String name);
}

在控制器ThemeController中使用Optional进行数据处理

package com.zhqx.missyou.api.v1;

import com.github.dozermapper.core.DozerBeanMapperBuilder;
import com.github.dozermapper.core.Mapper;
import com.zhqx.missyou.exception.http.NotFoundException;
import com.zhqx.missyou.model.Theme;
import com.zhqx.missyou.service.ThemeService;
import com.zhqx.missyou.vo.ThemePureVO;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.*;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Optional;

@RestController
@RequestMapping("theme")
@Validated
public class ThemeController {
    @Autowired
    private ThemeService themeService;

    @GetMapping("/by/names")
    public List<ThemePureVO> getThemeGroupByNames(@RequestParam(name = "names") String names) {
        List<String> nameList = Arrays.asList(names.split(","));
        List<Theme> themes = themeService.findByNames(nameList);
        List<ThemePureVO> list = new ArrayList<>();
        themes.forEach(theme -> {
            Mapper mapper = DozerBeanMapperBuilder.buildDefault();
            ThemePureVO vo = mapper.map(theme, ThemePureVO.class);
            list.add(vo);
        });
        return list;
    }

    @GetMapping("/name/{name}/with_spu")
    public Theme getThemeByNameWithSpu(@PathVariable(name = "name") String themeName){
        Optional<Theme> optionalTheme = this.themeService.findByName(themeName);
        return optionalTheme.orElseThrow(()-> new NotFoundException(30003));
    }
}

原文链接: https://marshucheng1.github.io/2021/02/19/springboot-qiyue-5/

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