java 常见方法，mapper，初始化list集合时赋值，批量新增-saveBatch，new Date()，各种判空，String、Integer对象比较equals()，排序，抛异常，分页查询_java savebatch

80.ConvertUtil

 List<GsFinalReport> gsFinalReports = ConvertUtil.convertList(result, GsFinalReport.class);
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81.ArrayUtils.toString()

将数字转换为字符串；

List<String> lst = Arrays.asList("a","b","c");
String str = ArrayUtils.toString(lst);
System.out.println(a); 		//[a,b,c]
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82.mapper.selectList()，返回某一字段的集合

通过实体类mapper赛选出结果，在结果集中取某一字段的结果集。

        List<String> collect = securityDeviceMapper.selectList(
        	new QueryWrapper<JcDSecurityDevice>()
                .lambda().eq(JcDSecurityDevice::getDeleteState, 0))
                .stream().map(JcDSecurityDevice::getImei).collect(Collectors.toList());
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83.mapper.selectOne(new QueryWrapper().lambda() .eq(AmsDAssetData::getDeleteState, 0))

从数据库查询一个符合某些条件的实体；

		//amsDAssetDataMapper : 实体对应的mapper，用于操作数据库
        AmsDAssetData one = amsDAssetDataMapper.selectOne(
        //AmsDAssetData ：实体类名称
        	new QueryWrapper<AmsDAssetData>()
        		.lambda()
        		.eq(AmsDAssetData::getFacilityCode, request.getFacilityCode())
        		.eq(AmsDAssetData::getDeleteState, 0)
            );
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84.new Date()

        amsDAssetData.setCreateTime(new Date());
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85.批量新增-saveBatch

  /**
     * 添加信息
     *
     * @param addBmsSMaintainSchemeParam
     * @return
     */
    @Override
    public void add(AddBmsSMaintainSchemeParam addBmsSMaintainSchemeParam) {
        BmsSMaintainScheme bmsSMaintainScheme = addBmsSMaintainSchemeParam.getBmsSMaintainScheme();
        int id = idManagementService.getId("s_maintain_scheme");
        bmsSMaintainScheme.setId(id);
        bmsSMaintainScheme.setDeleteState(0);
        bmsSMaintainSchemeMapper.insert(bmsSMaintainScheme);
        //关联关系表
        List<BmsRMaintainScheme> bmsRMaintainSchemeList = addBmsSMaintainSchemeParam.getBmsSStructureList();
        int bmsRMaintainSchemeId = idManagementService.getId("r_maintain_scheme", bmsRMaintainSchemeList.size());
        for (BmsRMaintainScheme bmsRStructureStyle : bmsRMaintainSchemeList) {
            bmsRStructureStyle.setId(bmsRMaintainSchemeId++ - bmsRMaintainSchemeList.size() + 1);
            bmsRStructureStyle.setSchemeId(id);
            bmsRStructureStyle.setDeleteState(0);
        }
        bmsRMaintainSchemeService.saveBatch(bmsRMaintainSchemeList);
    }
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86.初始化list集合时赋值

List<String> lst = Arrays.asList("明奎","Dk","The 8","胜宽");
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87.要素过多—>细看

  /**
     * 添加信息
     *
     * @param request
     * @return
     */
    @Override
    public BaseResponse add(AddAssetDataRequest request) {
        // 添加资产表信息
        AmsDAssetData amsDAssetData = new AmsDAssetData();
        int assetId = idManagementService.getId("ams_d_asset_data");
        BeanUtils.copyProperties(request, amsDAssetData);
        amsDAssetData.setId(assetId);
        amsDAssetData.setDeleteState(0);
        //取当前时间
        amsDAssetData.setCreateTime(new Date());
        amsDAssetData.setModifyTime(new Date());
        amsDAssetData.setModifyUserId(request.getCreateUserId());
        amsDAssetData.setFacilityStatus(1);
        AmsDAssetData one = amsDAssetDataMapper.selectOne(new QueryWrapper<AmsDAssetData>().lambda().eq(AmsDAssetData::getFacilityCode, request.getFacilityCode())
                .eq(AmsDAssetData::getDeleteState, 0));
        if (one != null) {
            return new BaseResponse(ResponseEnum.ERROR.getCode(),"该设备已存在!");
        }
        List<String> collect = securityDeviceMapper.selectList(new QueryWrapper<JcDSecurityDevice>()
                .lambda().eq(JcDSecurityDevice::getDeleteState, 0))
                .stream().map(JcDSecurityDevice::getImei).collect(Collectors.toList());
        if (StringUtils.isNotBlank(request.getAddress())) {
            amsDAssetData.setInstallAddr(request.getAddress());
            JcDSecurityDevice selectOne = securityDeviceMapper.selectOne(new QueryWrapper<JcDSecurityDevice>()
                    .lambda().eq(JcDSecurityDevice::getImei, request.getFacilityCode()));
            if (collect.contains(request.getFacilityCode())) {
                // 更新安装地址
                selectOne.setInstallAddr(request.getAddress());
                securityDeviceMapper.updateById(selectOne);
            }
        }

        int insert = amsDAssetDataMapper.insert(amsDAssetData);
        if (insert > 0) {
            // 添加资产附件信息
            String attachFiles = request.getAttachFiles();
            if (StringUtils.isNotBlank(attachFiles)) {
                List<String> strings = Arrays.asList(attachFiles.split(","));
                addAttachFiles(strings, assetId, request.getShapeType().toString(), request.getAssetName(), request.getCreateUserId());
            }
            return new BaseResponse(ResponseEnum.SUCCESS);
        }
        return new BaseResponse(ResponseEnum.ERROR.getCode(), "采集失败!");
    }
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88.MPJLambdaWrapper，mapper.selectJoinList()，CollectionUtils.isNotEmpty(lst)，.like()，.in()

@Override
    public List<BmsDMaintainHistoryUnit> getHisList(Integer msegmentId, String type, Integer year, Integer lastYear, List<Integer> unitIds) {
        MPJLambdaWrapper<BmsDMaintainHistoryUnit> objectMPJLambdaWrapper = new MPJLambdaWrapper<>();
//        QueryWrapper<BmsDMaintainHistoryUnit> queryWrapper = new QueryWrapper<>();
        objectMPJLambdaWrapper.selectAll(BmsDMaintainHistoryUnit.class).eq(BmsDMaintainHistoryUnit::getMsegmentId, msegmentId)
                .le(BmsDMaintainHistoryUnit::getYear, year)
                .eq(BmsDMaintainHistoryUnit::getYear, lastYear).eq(BmsDMaintainHistoryUnit::getDeleteState, 0);
        if (StringUtils.isNotBlank(type)) {
            objectMPJLambdaWrapper.like(BmsDMaintainHistoryUnit::getSchemeName, type);
        }
        if (CollectionUtils.isNotEmpty(unitIds)) {
            objectMPJLambdaWrapper.in(BmsDMaintainHistoryUnit::getUnitId, unitIds);
        }

        List<BmsDMaintainHistoryUnit> list = bmsDMaintainHistoryUnitMapper.selectJoinList(BmsDMaintainHistoryUnit.class, objectMPJLambdaWrapper);
        return list;
    }
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89.mapper.selectJoinPage()

	@Override
    public IPage<RmsDMsegmentResponse> selectPageList(GetMsegmentPageRequest rmsDMsegmentParam) {
        if (CollectionUtils.isEmpty(rmsDMsegmentParam.getDeptIds())) {
            rmsDMsegmentParam.setDeptIds(UserUtils.getDeptIds());
        }
        MPJLambdaWrapper mpjLambdaWrapper = selectLambdaWrapper(rmsDMsegmentParam);
        return rmsDMsegmentMapper.selectJoinPage(new Page<>(rmsDMsegmentParam.getPageNum(), rmsDMsegmentParam.getPageSize()), RmsDMsegmentResponse.class, mpjLambdaWrapper);
    }
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90.Collectors.groupingBy(MsegmentInfoResponse::getDeptName)

@Override
    public Map<String, List<MsegmentInfoResponse>> selectRouteByDept(GetMsegmentPageRequest rmsDMsegmentParam) {
        MPJLambdaWrapper mpjLambdaWrapper = selectLambdaWrapper(rmsDMsegmentParam);
        List<MsegmentInfoResponse> msegmentInfoResponseList = rmsDMsegmentMapper.selectJoinList(MsegmentInfoResponse.class, mpjLambdaWrapper);
        
        Map<String, List<MsegmentInfoResponse>> listMap = msegmentInfoResponseList.stream().collect(Collectors.groupingBy(MsegmentInfoResponse::getDeptName));
        return listMap;
    }
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91.实体中添加字段，不映射到数据库表 @TableField(exist = false)

@Data
@TableName("ria_d_project_scheme")
@ApiModel(value = "RiaDProjectScheme对象", description = "项目库维修方案表")
public class RiaDProjectScheme implements Serializable {

    private static final long serialVersionUID = 1L;

    @ApiModelProperty(value = "主键")
    @TableId(value = "id", type = IdType.INPUT)
    private Integer id;
    
    //关联查询出deptName存放在实体 	
 	@ApiModelProperty(value = "单位名称")
    @TableField(exist = false)
    private String deptName;
    
  	@ApiModelProperty(value = "指定国检车道pqi")
    private Double nationalPqi;
}
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92.mybatis-plus按条件查询数据库（eq、in）(构造链式结构)

List<RiaSUnitAnalysis> lstUnit = unitAnalysisMapper.selectList(new QueryWrapper<RiaSUnitAnalysis>().lambda()
.eq(RiaSUnitAnalysis::getYear, year)
.in(RiaSUnitAnalysis::getUnitId, unitIds));
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93.新建含初始值的list集合

calDiffParam.lstPQI = Arrays.asList(100.0);
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94.double判空

Double prior = 0.0;
boolean flag = prior.equals(Double.NaN); //prior = NaN 时，判断结果为真

prior == null || prior.equals(null) <------起不到判断作用
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95.String、Integer对象比较得用equals()

String a = "test1";
if(!a.equals("test1"));
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96.String判空

注：StringUtils 和 StringUtil 判空

String scheme = "";
boolean flag = StringUtils.isBlank(this.scheme);
flag = StringUtils.isNotEmpty(this.scheme);
flag = StringUtils.isEmpty(this.scheme);
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97.list判空

 if (m_lstGeneralParam == null || m_lstGeneralParam.size() <= 0) {
            return;
        }
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97.实体对象判空 (==null或!=null)

 AmsDAssetData one = amsDAssetDataMapper.selectOne(new QueryWrapper<AmsDAssetData>().lambda().
                .eq(AmsDAssetData::getDeleteState, 0));
        if (one != null) {
            return new BaseResponse(ResponseEnum.ERROR.getCode(),"该设备已存在!");
        }
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98. 遍历赋值

response.getLstBeforeRepair().forEach(param -> param.setMsegmentName(lstMsegment.get(0).getMsegmentName()));
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99. 排序

//从小到大：
lstKM.sort((a, b) -> {
            Double d1 = a.getPQI();
            Double d2 = b.getPQI();
            return d1.compareTo(d2);
        });
        
//从大到小：
lstKM.sort((a, b) -> {
            Double d1 = a.getPQI();
            Double d2 = b.getPQI();
            return d2.compareTo(d1);
        });
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100.抛出异常

if (CollectionUtils.isEmpty(lstPQI)) {
    throw new BusinessException(ResponseEnum.ERROR.getCode(), "PQI不能为空");
}
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101.在实现层抛出异常

if (one != null) {
            return new BaseResponse(ResponseEnum.ERROR.getCode(),"该设备已存在!");
        }
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