Spring Data非常方便，并且避免了样板代码，从而加快了开发速度。 但是，在某些情况下，注释查询不足以实现您可能想要实现的自定义功能。

因此，spring数据允许我们向Spring数据存储库添加自定义方法。 我将使用前一篇博客文章中的相同项目结构。

我们有一个名为Employee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;}
}

还有Spring Data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.*/
@Repository
public interface EmployeeRepository extends JpaRepository<Employee,Long>{}

假设我们要添加一些自定义的sql功能，例如使用LIKE语句查询并与未映射为实体的表联接。

这仅用于演示目的。 对于您的项目，您可能会有更好的架构。 再加上spring数据具有类似语句的开箱即用功能，请查看EndingWith，Containing，StartingWith 。

我们将创建奖金表并添加对雇员表的引用。

set schema 'spring_data_jpa_example';create table bonus(id serial primary key,employee_id integer,amount real,foreign key (employee_id) references employee (id),unique (employee_id));insert into bonus
( employee_id, amount)
VALUES(1, 100);

我们要实现的sql查询将查询名称以指定文本开头且奖金大于一定数量的员工。 在jdbc中，我们必须传递与字符'％'串联在一起的变量。

所以我们需要一个像这样的本地jpa查询

Query query = entityManager.createNativeQuery("select e.* from spring_data_jpa_example.bonus b, spring_data_jpa_example.employee e\n" +"where e.id = b.employee_id " +"and e.firstname LIKE ? " +"and b.amount> ? ", Employee.class);query.setParameter(1, firstName + "%");query.setParameter(2, bonusAmount);

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。 我们的界面必须遵循$ {Original Repository name} Custom的命名约定。 因此，描述我们自定义功能的界面应为

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> getFirstNamesLikeAndBonusBigger(String firstName, Double bonusAmount);}

实施应该是

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 {@PersistenceContextEntityManager entityManager;@Overridepublic List<Employee> getFirstNamesLikeAndBonusBigger(String firstName, Double bonusAmount) {Query query = entityManager.createNativeQuery("select e.* from spring_data_jpa_example.bonus b, spring_data_jpa_example.employee e\n" +"where e.id = b.employee_id " +"and e.firstname LIKE ? " +"and b.amount> ? ", Employee.class);query.setParameter(1, firstName + "%");query.setParameter(2, bonusAmount);return query.getResultList();}
}

并且我们应该更改原始的spring数据存储库以继承自定义功能。

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 {
}

似乎是一种不错的构图方式。 现在让我们向控制器添加一个方法，该方法将调用此自定义方法

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.RequestParam;import org.springframework.web.bind.annotation.RestController;import java.util.List;/*** Created by gkatzioura on 6/2/16.*/
@RestController
public class TestController {@Autowiredprivate EmployeeRepository employeeRepository;@RequestMapping("/employee")public List<Employee> getTest() {return employeeRepository.findAll();}@RequestMapping("/employee/filter")public List<Employee> getFiltered(String firstName,@RequestParam(defaultValue = "0") Double bonusAmount) {return employeeRepository.getFirstNamesLikeAndBonusBigger(firstName,bonusAmount);}}

源代码可以在github上找到。

翻译自: https://www.javacodegeeks.com/2016/06/add-custom-functionality-spring-data-repository.html