JPA带过滤条件和分页的写法

假设有个Entity为Employee

package com.mycompany.myapp.domain;

import io.swagger.v3.oas.annotations.media.Schema;
import org.hibernate.annotations.Cache;
import org.hibernate.annotations.CacheConcurrencyStrategy;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
import java.io.Serializable;

/**
 * The Employee entity.
 */
@Schema(description = "The Employee entity.")
@Entity
@Table(name = "employee")
@Cache(usage = CacheConcurrencyStrategy.READ_WRITE)
@SuppressWarnings("common-java:DuplicatedBlocks")
public class Employee implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;

    /**
     * The firstname attribute.
     */
    @Schema(description = "The firstname attribute.")
    @Column(name = "first_name")
    private String firstName;

    @Column(name = "last_name")
    private String lastName;

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

    @Column(name = "phone_number")
    private String phoneNumber;

    // jhipster-needle-entity-add-field - JHipster will add fields here

    public Long getId() {
        return this.id;
    }

    public Employee id(Long id) {
        this.setId(id);
        return this;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getFirstName() {
        return this.firstName;
    }

    public Employee firstName(String firstName) {
        this.setFirstName(firstName);
        return this;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return this.lastName;
    }

    public Employee lastName(String lastName) {
        this.setLastName(lastName);
        return this;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getEmail() {
        return this.email;
    }

    public Employee email(String email) {
        this.setEmail(email);
        return this;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getPhoneNumber() {
        return this.phoneNumber;
    }

    public Employee phoneNumber(String phoneNumber) {
        this.setPhoneNumber(phoneNumber);
        return this;
    }

    public void setPhoneNumber(String phoneNumber) {
        this.phoneNumber = phoneNumber;
    }

    // jhipster-needle-entity-add-getters-setters - JHipster will add getters and setters here

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (!(o instanceof Employee)) {
            return false;
        }
        return id != null && id.equals(((Employee) o).id);
    }

    @Override
    public int hashCode() {
        // see https://vladmihalcea.com/how-to-implement-equals-and-hashcode-using-the-jpa-entity-identifier/
        return getClass().hashCode();
    }

    // prettier-ignore
    @Override
    public String toString() {
        return "Employee{" +
            "id=" + getId() +
            ", firstName='" + getFirstName() + "'" +
            ", lastName='" + getLastName() + "'" +
            ", email='" + getEmail() + "'" +
            ", phoneNumber='" + getPhoneNumber() + "'" +
            "}";
    }
}

Repository

添加findAll接口，详细代码如下：

package com.mycompany.myapp.repository;

import com.mycompany.myapp.domain.Employee;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.data.jpa.repository.*;
import org.springframework.stereotype.Repository;

import java.util.List;

/**
 * Spring Data JPA repository for the Employee entity.
 */
@SuppressWarnings("unused")
@Repository
public interface EmployeeRepository extends JpaRepository<Employee, Long> {
    List<Employee> findByEmail(String email);

    Page<Employee> findAll(Specification<Employee> spec, Pageable pageable);
}

调用方Client

    public void run() {
        Pageable pageable = PageRequest.of(0, 20);
        String email = "abc@abc.com";
        Specification<Employee> spec = (root, query, criteriaBuilder) -> {
            if (email == null) {
                return criteriaBuilder.isTrue(criteriaBuilder.literal(true));
            }
            return criteriaBuilder.equal(root.get("email"), email);
        };
        Page<Employee> employeePage = employeeRepository.findAll(spec, pageable);
        System.out.println("employeePage:" + employeePage.getContent());
    }