JPA进行CriteriaQuery进行查询注意事项

1.pojo类

@Entity@Table(name = "report_workload")@JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})@JsonIdentityInfo(generator = JSOGGenerator.class)public class ReportWorkload {    private int id;    private Integer flowWorkItemApprId;    private Integer busId;    private Integer deptId;    private Integer staffId;    private Integer busiValueIndustryId;    private Integer busiValueScaleId;    private String taskName;    private Integer count;    private BigDecimal amount;    private Date approvalTime;    private String reportTime;    private String deptName;    private String staffName;    @Id    @Column(name = "id")    @GeneratedValue(strategy = GenerationType.AUTO)    public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    @Basic    @Column(name = "flow_work_item_appr_id")    public Integer getFlowWorkItemApprId() {        return flowWorkItemApprId;    }    public void setFlowWorkItemApprId(Integer flowWorkItemApprId) {        this.flowWorkItemApprId = flowWorkItemApprId;    }    @Basic    @Column(name = "bus_id")    public Integer getBusId() {        return busId;    }    public void setBusId(Integer busId) {        this.busId = busId;    }    @Basic    @Column(name = "dept_id")    public Integer getDeptId() {        return deptId;    }    public void setDeptId(Integer deptId) {        this.deptId = deptId;    }    @Basic    @Column(name = "staff_id")    public Integer getStaffId() {        return staffId;    }    public void setStaffId(Integer staffId) {        this.staffId = staffId;    }    @Basic    @Column(name = "busi_value_industry_id")    public Integer getBusiValueIndustryId() {        return busiValueIndustryId;    }    public void setBusiValueIndustryId(Integer busiValueIndustryId) {        this.busiValueIndustryId = busiValueIndustryId;    }    @Basic    @Column(name = "busi_value_scale_id")    public Integer getBusiValueScaleId() {        return busiValueScaleId;    }    public void setBusiValueScaleId(Integer busiValueScaleId) {        this.busiValueScaleId = busiValueScaleId;    }    @Basic    @Column(name = "task_name")    public String getTaskName() {        return taskName;    }    public void setTaskName(String taskName) {        this.taskName = taskName;    }    @Basic    @Column(name = "count")    public Integer getCount() {        return count;    }    public void setCount(Integer count) {        this.count = count;    }    @Basic    @Column(name = "amount")    public BigDecimal getAmount() {        return amount;    }    public void setAmount(BigDecimal amount) {        this.amount = amount;    }    @Basic    @Column(name = "approval_time")    public Date getApprovalTime() {        return approvalTime;    }    public void setApprovalTime(Date approvalTime) {        this.approvalTime = approvalTime;    }    @Basic    @Column(name = "report_time")    public String getReportTime() {        return reportTime;    }    public void setReportTime(String reportTime) {        this.reportTime = reportTime;    }    @Transient    public String getDeptName() {        return deptName;    }    public void setDeptName(String deptName) {        this.deptName = deptName;    }    @Transient    public String getStaffName() {        return staffName;    }    public void setStaffName(String staffName) {        this.staffName = staffName;    }    @Override    public boolean equals(Object o) {        if (this == o) return true;        if (!(o instanceof ReportWorkload)) return false;        ReportWorkload that = (ReportWorkload) o;        return id == that.id;    }    @Override    public int hashCode() {        return id;    }    public ReportWorkload(int id, Integer flowWorkItemApprId,                          Integer busId, Integer deptId, Integer staffId,                          Integer busiValueIndustryId, Integer busiValueScaleId,                          String taskName, Long count, BigDecimal amount,                          Date approvalTime, String reportTime) {        this.id = id;        this.flowWorkItemApprId = flowWorkItemApprId;        this.busId = busId;        this.deptId = deptId;        this.staffId = staffId;        this.busiValueIndustryId = busiValueIndustryId;        this.busiValueScaleId = busiValueScaleId;        this.taskName = taskName;        this.count = Integer.parseInt(count+"");//        this.count = count;        this.amount = amount;        this.approvalTime = approvalTime;        this.reportTime = reportTime;    }    public ReportWorkload() {    }}

在进行聚合函数sum求和时，原来是int会自动提升为long,不做特殊处理就会报以下错误了：

org.hibernate.hql.internal.ast.DetailedSemanticException: Unable to locate appropriate constructor on class [com.changfa.frame.data.entity.report.ReportWorkload]. Expected arguments are: int, int, int, int, int, int, int, java.lang.String, long, java.math.BigDecimal, java.util.Date, java.lang.Stringat org.hibernate.hql.internal.ast.tree.ConstructorNode.resolveConstructor(ConstructorNode.java:182)at org.hibernate.hql.internal.ast.tree.ConstructorNode.prepare(ConstructorNode.java:144)at org.hibernate.hql.internal.ast.HqlSqlWalker.processConstructor(HqlSqlWalker.java:1092)at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectExpr(HqlSqlBaseWalker.java:2359)

会提示你查询数据库返回的类型和你的构造函数类型对应不上。

service层：

通过注解将EntityManager加载进来：

    @PersistenceContext    private EntityManager em;

查询方法：

 public List<ReportWorkload> reportworkloadsearch(String reportTime, String deptId, String staffId, String typeId, String industryId) {        List<ReportWorkload> reportWorkloadList = new ArrayList<>();        CriteriaBuilder criteriaBuilder = em.getCriteriaBuilder();        CriteriaQuery<ReportWorkload> cq = criteriaBuilder.createQuery(ReportWorkload.class);        Root<ReportWorkload> rt = cq.from(ReportWorkload.class);        cq.multiselect(rt.get("id"),rt.get("flowWorkItemApprId"),                rt.get("busId"),rt.get("deptId"),rt.get("staffId"),                rt.get("busiValueIndustryId"),rt.get("busiValueScaleId"),                rt.get("taskName"),criteriaBuilder.sum(rt.get("count")),                criteriaBuilder.sum(rt.get("amount")),rt.get("approvalTime"),                rt.get("reportTime"));        if(reportTime!=null&&reportTime!=""){            cq.where(criteriaBuilder.equal(rt.get("reportTime"), reportTime));        }        if(deptId!=null&&deptId!=""){            cq.where(criteriaBuilder.equal(rt.get("deptId"), Integer.parseInt(deptId)));        }        if(staffId!=null&&staffId!=""){            cq.where(criteriaBuilder.equal(rt.get("staffId"), Integer.parseInt(staffId)));        }        if(typeId!=null&&typeId!=""){            cq.where(criteriaBuilder.equal(rt.get("typeId"), Integer.parseInt(typeId)));        }        if(industryId!=null&&industryId!=""){            cq.where(criteriaBuilder.equal(rt.get("industryId"), Integer.parseInt(industryId)));        }        cq.groupBy(rt.get("busId"),rt.get("deptId"),rt.get("taskName"));        reportWorkloadList = em.createQuery(cq).getResultList();        return reportWorkloadList;    }

在进行cq.multiselect自定义返回字段时，必须在对应的pojo中给一个对应的返回字段构造函数