Page<V0>对象互转Page<V1>

深藏阁楼爱情的钟 2021-10-14 22:18 666阅读 0赞

## 原理都是取出Page包装的对象，然后实现对象之间的互传，在返回Page,这里介绍几种实现方式 ##

### 1. 这个mapper是基于mapStruct，常用来实现Model,DTO的互转， ###

<dependency>
            <groupId>org.mapstruct</groupId>
            <artifactId>mapstruct-jdk8</artifactId>
            <version>1.3.0.Final</version>
        </dependency>

引 Jar,pom文件引Jar，还有build插件，Maven 编译等，稍微麻烦些

<plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>3.6.1</version>
                    <configuration>
                        <source>${java.version}</source>
                        <target>${java.version}</target>
                        <annotationProcessorPaths>
                            <path>
                                <groupId>org.projectlombok</groupId>
                                <artifactId>lombok</artifactId>
                                <version>1.16.22</version>
                            </path>
                            <path>
                                <groupId>org.mapstruct</groupId>
                                <artifactId>mapstruct-processor</artifactId>
                                <version>1.3.0.Final</version>
                            </path>
                        </annotationProcessorPaths>
                        <compilerArgs>
                            <arg>-Amapstruct.suppressGeneratorTimestamp=true</arg>
                            <arg>-Amapstruct.defaultComponentModel=spring</arg>
                        </compilerArgs>
                    </configuration>
                </plugin>

以下是demo示例

public Page<CustomerDTO> page2(){
            PageRequest pageRequest = PageRequest.of(0, 20, Sort.Direction.DESC,"customerNumber");
            Page<CustomersEntity> all = customerRepo.findAll(pageRequest);
    
            Page<CustomerDTO> map = all.map(e -> customerMapper.toCustomerDto(e));
            return map;
        }

### 2. 基于Json实现对象的互转，这里我用的是Hutool包，（注意这里如果涉及时间类型的字段映射，可能会转换错误） ###

public Page<CustomerDTO> page3(){
            PageRequest pageRequest = PageRequest.of(0, 20, Sort.Direction.DESC,"customerNumber");
            Page<CustomersEntity> all = customerRepo.findAll(pageRequest);
    
            Page<CustomerDTO> map = all.map(e -> JSONUtil.toBean(JSONUtil.toJsonStr(e),CustomerDTO.class));
            return map;
        }

注意，Hutool包的JsonUtil在转换对象的时候，有时候会因为时间类型（LocalDateTime）的字段，转换错误，第一种Mapper方式还没试

### 3. 使用构造方法实现对象的转换，在V0中定义如下的构造方法即可,注意参数 ###

public MoveRecordVo(MoveInfo moveInfo) {
            this.assetId = moveInfo.getAssetId();
            this.assetName = moveInfo.getAssetName();
            this.startTime = moveInfo.getStartTime();
            this.endTime = moveInfo.getEndTime();
            this.moveTime = null;
            this.moveStatus = moveInfo.getMoveStatus();
            this.remarks = moveInfo.getRemarks();
            this.isOperate = null;
        }

这样在转换对象的时候，就很方便了

Page<MoveInfo> all = moveInfoRepository.findAll(pageRequest);
    Page<MoveRecordVo> map = all.map(e -> new MoveRecordVo(e));

### 4. 还有一种方法，稍微麻烦一点，就是先把Page转成List,再根据之前的分页参数（JPA，根据前端传参，计算好的分页参数Pageable）返回封装Page,代码如下,不想细整理了 ###

public Page<TranscodeRecordVo> findAll(TranscodeDto transcodeDto, int page, int rows, String sord, String sidx) {
            if (StrUtil.isBlankIfStr(sidx)) {
                sidx = "transcodeId";
            }
            PageRequest pageRequest = PageRequest.of(page - 1, rows, Sort.by(Sort.Order.asc(sidx), Sort.Order.desc("collectTime")));
            Page<Transcode> all = transcodeRepository.findAll((Specification<Transcode>) (root, query, cb) -> {
                List<Predicate> predicates = Lists.newArrayList();
                predicates.add(cb.equal(root.get("groupId"), transcodeDto.getGroupId()));
    
                if (!StrUtil.isBlankIfStr(transcodeDto.getAssetId())) {
                    predicates.add(cb.equal(root.get("assetId"), transcodeDto.getAssetId()));
                }
                if (!StrUtil.isBlankIfStr(transcodeDto.getAssetName())) {
                    predicates.add(cb.like(root.get("assetName"), "%" + transcodeDto.getAssetName() + "%"));
                }
                if (!StrUtil.isBlankIfStr(transcodeDto.getTranscodeStatus())) {
                    predicates.add(cb.equal(root.get("transcodeStatus"), transcodeDto.getTranscodeStatus()));
                }
                if (!StrUtil.isBlankIfStr(transcodeDto.getFromStartTime())) {
                    predicates.add(cb.greaterThanOrEqualTo(root.get("endTime"), transcodeDto.getFromStartTime()));
                }
                if (!StrUtil.isBlankIfStr(transcodeDto.getToEndTime())) {
                    predicates.add(cb.lessThanOrEqualTo(root.get("endTime"), transcodeDto.getToEndTime()));
                }
                return cb.and(predicates.toArray(new Predicate[0]));
            }, pageRequest);
    
            ArrayList<TranscodeRecordVo> list = Lists.newArrayList();
    
            all.getContent().forEach(e -> {
                TranscodeRecordVo vo = new TranscodeRecordVo();
                BeanUtil.copyProperties(e, vo);
                list.add(vo);
            });
    
            list.forEach(e -> {
                if (NodeResultEnum.TranscodeStatus.STARTED.getKey().equals(e.getTranscodeStatus())) {
                    e.setTransTime(DateUtil.formatBetween(ChronoUnit.MILLIS.between(e.getStartTime(), LocalDateTime.now()), BetweenFormater.Level.SECOND));
                } else {
                    e.setTransTime(DateUtil.formatBetween(ChronoUnit.MILLIS.between(e.getStartTime(), e.getEndTime()), BetweenFormater.Level.SECOND));
                }
                if (NodeResultEnum.TranscodeStatus.FAILED.getKey().equals(e.getTranscodeStatus())) {
                    e.setIsOperate(YesOrNoEnum.YES.getCode());
                } else {
                    e.setIsOperate(YesOrNoEnum.NO.getCode());
                }
            });
            return new PageImpl<>(list, all.getPageable(), all.getTotalElements());
        }

[这里是我业务中的代码，关于List,Page对象，稍微复杂点的操作][List_Page]

[List_Page]: https://blog.csdn.net/qq_42105629/article/details/101015641