将自定义方法添加到Spring Data Repository存储库中

╰半橙微兮° 2023-09-26 10:52 15阅读 0赞

Spring Data非常方便，可以加快开发速度，避免样板代码。

但是，在某些情况下，注释查询对于您可能希望实现的自定义功能是不够的。

因此，弹簧数据允许我们将自定义方法添加到弹簧数据存储库。

我们有一个名为“员工”的实体：

package com.gkatzioura.springdata.jpa.persistence.entity;
    
    import javax.persistence.*;
    
    /**
     * Created by gkatzioura on 6/2/16.
     */
    @Entity
    @Table(name = "employee", schema="spring_data_jpa_example")
    public class Employee {
    
        @Id
        @Column(name = "id")
        @GeneratedValue(strategy = GenerationType.SEQUENCE)
        private Long id;
    
        @Column(name = "firstname")
        private String firstName;
    
        @Column(name = "lastname")
        private String lastname;
    
        @Column(name = "email")
        private String email;
    
        @Column(name = "age")
        private Integer age;
    
        @Column(name = "salary")
        private Integer salary;
    
        public Long getId() {
            return id;
        }
    
        public void setId(Long id) {
            this.id = id;
        }
    
        public String getFirstName() {
            return firstName;
        }
    
        public void setFirstName(String firstName) {
            this.firstName = firstName;
        }
    
        public String getLastname() {
            return lastname;
        }
    
        public void setLastname(String lastname) {
            this.lastname = lastname;
        }
    
        public String getEmail() {
            return email;
        }
    
        public void setEmail(String email) {
            this.email = email;
        }
    
        public Integer getAge() {
            return age;
        }
    
        public void setAge(Integer age) {
            this.age = age;
        }
    
        public Integer getSalary() {
            return salary;
        }
    
        public void setSalary(Integer salary) {
            this.salary = salary;
        }
    }

以及弹簧数据存储库：

package com.gkatzioura.springdata.jpa.persistence.repository;
    
    import com.gkatzioura.springdata.jpa.persistence.entity.Employee;
    import org.springframework.data.jpa.repository.JpaRepository;
    import org.springframework.stereotype.Repository;
    
    /**
     * Created by gkatzioura on 6/2/16.
     */
    public interface EmployeeRepository extends JpaRepository<Employee,Long>{
    
    }

假设我们要添加一些自定义 SQL 功能，例如使用 LIKE 语句进行查询。即使在 JDBC 中也不完全支持此功能，因为我们必须传递与字符 '%' 串联的变量。

因此，我们需要的是一个像这样的本机JPA查询：

Query query = entityManager.createNativeQuery("SELECT em.* FROM spring_data_jpa_example.employee as em " +
        "WHERE em.firstname LIKE ?", Employee.class);
    query.setParameter(1, firstName + "%");

为了将此功能添加到我们的Spring数据存储库中，我们必须添加一个接口。我们的接口必须遵循 的命名约定`${Original Repository name}Custom`。因此，描述我们的自定义功能的界面应该是

package com.gkatzioura.springdata.jpa.persistence.repository;
    
    import com.gkatzioura.springdata.jpa.persistence.entity.Employee;
    
    import java.util.List;
    
    /**
     * Created by gkatzioura on 6/3/16.
     */
    public interface EmployeeRepositoryCustom {
    
        List<Employee> getFirstNamesLike(String firstName);
    
    }

实现应该是：

package com.gkatzioura.springdata.jpa.persistence.repository;
    
    import com.gkatzioura.springdata.jpa.persistence.entity.Employee;
    import org.springframework.stereotype.Repository;
    import org.springframework.transaction.annotation.Transactional;
    
    import javax.persistence.EntityManager;
    import javax.persistence.PersistenceContext;
    import javax.persistence.Query;
    import java.util.List;
    
    /**
     * Created by gkatzioura on 6/3/16.
     */
    @Repository
    @Transactional(readOnly = true)
    public class EmployeeRepositoryImpl implements EmployeeRepositoryCustom {
    
        @PersistenceContext
        EntityManager entityManager;
    
        @Override
        public List<Employee> getFirstNamesLike(String firstName) {
            Query query = entityManager.createNativeQuery("SELECT em.* FROM spring_data_jpa_example.employee as em " +
                    "WHERE em.firstname LIKE ?", Employee.class);
            query.setParameter(1, firstName + "%");
    
            return query.getResultList();
        }
    }

我们应该更改原始的Spring数据存储库，以便继承自定义功能。

package com.gkatzioura.springdata.jpa.persistence.repository;
    
    import com.gkatzioura.springdata.jpa.persistence.entity.Employee;
    import org.springframework.data.jpa.repository.JpaRepository;
    import org.springframework.stereotype.Repository;
    
    /**
     * Created by gkatzioura on 6/2/16.
     */
    @Repository
    public interface EmployeeRepository extends JpaRepository<Employee,Long>, EmployeeRepositoryCustom {
    
    }

似乎是一种很好的构图方式。

现在，让我们向将调用此自定义方法的控制器添加一个方法：

package com.gkatzioura.springdata.jpa.controller;
    
    import com.gkatzioura.springdata.jpa.persistence.entity.Employee;
    import com.gkatzioura.springdata.jpa.persistence.repository.EmployeeRepository;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    import java.util.List;
    
    /**
     * Created by gkatzioura on 6/2/16.
     */
    @RestController
    public class TestController {
    
        @Autowired
        private EmployeeRepository employeeRepository;
    
        @RequestMapping("/employee")
        public List<Employee> getTest() {
    
            return employeeRepository.findAll();
        }
    
        @RequestMapping("/employee/filter")
        public List<Employee> getFiltered(String firstName) {
    
            return employeeRepository.getFirstNamesLike(firstName);
        }
    
    }

源代码可以在 [GitHub][] 上找到。

[GitHub]: https://github.com/gkatzioura/egkatzioura.wordpress.com/tree/master/SpringDataJPAIntegration