java - 创建动态 JPA 查询

Question

我有一个包含许多字段作为查询过滤器的 View ，并且我正在使用 JPA 派生查询，但是为每个字段/过滤器组合创建所有查询将是乏味且漫长的。

我发现我可以为其创建动态查询，但不确定如何创建。

到目前为止，我已经在我的存储库中创建了这些查询，但仍然需要更多:

 public interface EmployeeReportInfoViewRepository extends PagingAndSortingRepository<EmployeeReportInfo, Long> {

 List<EmployeeReportInfo> findByControlNumber(String controlNmber);

 List<EmployeeReportInfo> findByManager(String manager);

 List<EmployeeReportInfo> findByofficeLocation(String officeLocation);

 List<EmployeeReportInfo> findByBenchFlag(char benchFlag);

 List<EmployeeReportInfo> findByBillableFlag(char billableFlag);

 List<EmployeeReportInfo> findByEnableFlag(boolean enableFlag);

 List<EmployeeReportInfo> findByLastNameAndFirstNameAndControlNumber(String lastName, String firstName,String controlNumber);

 List<EmployeeReportInfo> findByLastNameAndFirstNameAndControlNumberAndManager(String lastName, String firstName,String controlNmber,String manager);

 List<EmployeeReportInfo> findByLastNameAndFirstNameAndControlNumberAndManagerAndOfficeLocation(String lastName, String firstName,String controlNmber,String manager,String officeLocation);

 List<EmployeeReportInfo> findByLastNameAndFirstNameAndControlNumberAndManagerAndOfficeLocationAndBenchFlag(String lastName, String firstName,String controlNmber,String manager,String officeLocation, char benchFlag);

 List<EmployeeReportInfo> findByLastNameAndFirstNameAndControlNumberAndManagerAndOfficeLocationAndBenchFlagAndBillableFlag(String lastName, String firstName,String controlNmber,String manager,String officeLocation, char benchFlag,char bllableFlag);

 List<EmployeeReportInfo> findByLastNameAndFirstNameAndControlNumberAndManagerAndOfficeLocationAndBenchFlagAndBillableFlagAndEnableFlagAndStartGreaterThanEqualAndEndLessThanEqual
 (String lastName, String firstName,String controlNmber,String manager,String officeLocation, char benchFlag,char bllableFlag, 
         boolean emableFlag, Date start,Date end); 


}

@Entity
@Table(name = "employee_report_view")
public class EmployeeReportInfo {

    @Id
    @Column(name = "employee_id")
    private Long id;

    private String name;

    private Date start;

    private Date end;

    @Column(name = "control_number")
    private String controlNumber;

    @Column(name = "enable_flag")
    private boolean enableFlag;

    @Column(name = "billable_flag")
    private char billableFlag;

    @Column(name = "bench_flag")
    private char benchFlag;

    @Column(name = "office_location")
    private String officeLocation;

    @Column(name = "manager")
    private String manager;

    /**
     * @return the id
     */
    public Long getId() {
        return id;
    }

    /**
     * @return the name
     */
    public String getName() {
        return name;
    }

    /**
     * @param name the name to set
     */
    public void setName(String name) {
        this.name = name;
    }

    /**
     * @param id the id to set
     */
    public void setId(Long id) {
        this.id = id;
    }


    /**
     * @return the start
     */
    public Date getStart() {
        return start;
    }

    /**
     * @param start the start to set
     */
    public void setStart(Date start) {
        this.start = start;
    }

    /**
     * @return the end
     */
    public Date getEnd() {
        return end;
    }

    /**
     * @param end the end to set
     */
    public void setEnd(Date end) {
        this.end = end;
    }

    /**
     * @return the controlNumber
     */
    public String getControlNumber() {
        return controlNumber;
    }

    /**
     * @param controlNumber the controlNumber to set
     */
    public void setControlNumber(String controlNumber) {
        this.controlNumber = controlNumber;
    }

    /**
     * @return the enableFlag
     */
    public boolean isEnableFlag() {
        return enableFlag;
    }

    /**
     * @param enableFlag the enableFlag to set
     */
    public void setEnableFlag(boolean enableFlag) {
        this.enableFlag = enableFlag;
    }

    /**
     * @return the billableFlag
     */
    public char getBillableFlag() {
        return billableFlag;
    }

    /**
     * @param billableFlag the billableFlag to set
     */
    public void setBillableFlag(char billableFlag) {
        this.billableFlag = billableFlag;
    }

    /**
     * @return the benchFlag
     */
    public char getBenchFlag() {
        return benchFlag;
    }

    /**
     * @param benchFlag the benchFlag to set
     */
    public void setBenchFlag(char benchFlag) {
        this.benchFlag = benchFlag;
    }

    /**
     * @return the officeLocation
     */
    public String getOfficeLocation() {
        return officeLocation;
    }

    /**
     * @param officeLocation the officeLocation to set
     */
    public void setOfficeLocation(String officeLocation) {
        this.officeLocation = officeLocation;
    }

    /**
     * @return the manager
     */
    public String getManager() {
        return manager;
    }

    /**
     * @param manager the manager to set
     */
    public void setManager(String manager) {
        this.manager = manager;
    }

}

Answer 1

我能理解你的需求:你想根据表单下发的url动态生成查询条件。我们假设url后端映射到一个HashMap<String,String> .

例如，网址:

127.0.0.1/employees?nameContains=jack&ageEquals=10

map :

HashMap<String, String>:key:nameContains,value:jack,key:ageEuqals,value:10

Spring 框架可以自动完成此映射( RequestParamMapMethodArgumentResolver )。您需要做的就是通过这张 map 动态生成规范( Specification )。

1. 使用reflect获取字段对应的属性类型:name=>String,age=>Integer
2. 使用CriteriaBuilder构建查询条件，具有完善的API，例如:

Predicate like(Expression x, String pattern); => contains

Predicate equal(Expression x, Expression y); => equal

组合您的查询条件(或、和)

您会收到一份规范。

这是一个比较复杂的解决思路，需要前台组件和后端配合，但是会很方便。

我说的比较简单和笼统，还有很多细节(比如嵌套属性，一对一，一对多等)

另外，你可以看看http://www.querydsl.com/