SpringData_Repository接口概述

• Repository 接口是 Spring Data 的一个核心接口，它不提供任何方法，开发者需要在自己定义的接口中声明需要的方法  public interface Repository<T, ID extends Serializable> { }

• Spring Data可以让我们只定义接口，只要遵循 Spring Data的规范，就无需写实现类。

• 与继承 Repository 等价的一种方式，就是在持久层接口上使用 @RepositoryDefinition 注解，并为其指定 domainClass 和 idClass 属性。如下两种方式是完全等价的

Repository 的子接口

• 基础的 Repository 提供了最基本的数据访问功能，其几个子接口则扩展了一些功能。它们的继承关系如下：

1.Repository： 仅仅是一个标识，表明任何继承它的均为仓库接口类

2.CrudRepository： 继承 Repository，实现了一组 CRUD 相关的方法

3.PagingAndSortingRepository： 继承 CrudRepository，实现了一组分页排序相关的方法

4.JpaRepository： 继承 PagingAndSortingRepository，实现一组 JPA 规范相关的方法

5.自定义的 XxxxRepository 需要继承 JpaRepository，这样的 XxxxRepository 接口就具备了通用的数据访问控制层的能力。

6.JpaSpecificationExecutor： 不属于Repository体系，实现一组 JPA Criteria 查询相关的方法

SpringData 方法定义规范

• 简单条件查询：查询某一个实体类或者集合
• 按照 Spring Data 的规范，查询方法以 find | read | get 开头， 涉及条件查询时，条件的属性用条件关键字连接，要注意的是：条件属性以首字母大写。

• 例如：定义一个 Entity 实体类 class User｛ 	private String firstName; 	private String lastName; ｝ 使用And条件连接时，应这样写： findByLastNameAndFirstName(String lastName,String firstName); 条件的属性名称与个数要与参数的位置与个数一一对应
  

  　　支持的关键字

Table 4. Supported keywords inside method names

	Sample	JPQL snippet
And	findByLastnameAndFirstname	… where x.lastname = ?1 and x.firstname = ?2
Or	findByLastnameOrFirstname	… where x.lastname = ?1 or x.firstname = ?2
Is,Equals	findByFirstname,findByFirstnameIs,findByFirstnameEquals	… where x.firstname = ?1
Between	findByStartDateBetween	… where x.startDate between ?1 and ?2
LessThan	findByAgeLessThan	… where x.age < ?1
LessThanEqual	findByAgeLessThanEqual	… where x.age <= ?1
GreaterThan	findByAgeGreaterThan	… where x.age > ?1
GreaterThanEqual	findByAgeGreaterThanEqual	… where x.age >= ?1
After	findByStartDateAfter	… where x.startDate > ?1
Before	findByStartDateBefore	… where x.startDate < ?1
IsNull	findByAgeIsNull	… where x.age is null
IsNotNull,NotNull	findByAge(Is)NotNull	… where x.age not null
Like	findByFirstnameLike	… where x.firstname like ?1
NotLike	findByFirstnameNotLike	… where x.firstname not like ?1
StartingWith	findByFirstnameStartingWith	… where x.firstname like ?1(parameter bound with appended %)
EndingWith	findByFirstnameEndingWith	… where x.firstname like ?1(parameter bound with prepended %)
Containing	findByFirstnameContaining	… where x.firstname like ?1(parameter bound wrapped in %)
OrderBy	findByAgeOrderByLastnameDesc	… where x.age = ?1 order by x.lastname desc
Not	findByLastnameNot	… where x.lastname <> ?1
In	findByAgeIn(Collection<Age> ages)	… where x.age in ?1
NotIn	findByAgeNotIn(Collection<Age> age)	… where x.age not in ?1
True	findByActiveTrue()	… where x.active = true
False	findByActiveFalse()	… where x.active = false
IgnoreCase	findByFirstnameIgnoreCase	… where UPPER(x.firstame) = UPPER(?1)

Keyword	Sample	JPQL snippet
And	findByLastnameAndFirstname	… where x.lastname = ?1 and x.firstname = ?2
Or	findByLastnameOrFirstname	… where x.lastname = ?1 or x.firstname = ?2
Is,Equals	findByFirstname,findByFirstnameIs,findByFirstnameEquals	… where x.firstname = ?1
Between	findByStartDateBetween	… where x.startDate between ?1 and ?2
LessThan	findByAgeLessThan	… where x.age < ?1
LessThanEqual	findByAgeLessThanEqual	… where x.age <= ?1
GreaterThan	findByAgeGreaterThan	… where x.age > ?1
GreaterThanEqual	findByAgeGreaterThanEqual	… where x.age >= ?1
After	findByStartDateAfter	… where x.startDate > ?1
Before	findByStartDateBefore	… where x.startDate < ?1
IsNull	findByAgeIsNull	… where x.age is null
IsNotNull,NotNull	findByAge(Is)NotNull	… where x.age not null
Like	findByFirstnameLike	… where x.firstname like ?1
NotLike	findByFirstnameNotLike	… where x.firstname not like ?1
StartingWith	findByFirstnameStartingWith	… where x.firstname like ?1(parameter bound with appended %)
EndingWith	findByFirstnameEndingWith	… where x.firstname like ?1(parameter bound with prepended %)
Containing	findByFirstnameContaining	… where x.firstname like ?1(parameter bound wrapped in %)
OrderBy	findByAgeOrderByLastnameDesc	… where x.age = ?1 order by x.lastname desc
Not	findByLastnameNot	… where x.lastname <> ?1
In	findByAgeIn(Collection<Age> ages)	… where x.age in ?1
NotIn	findByAgeNotIn(Collection<Age> age)	… where x.age not in ?1
True	findByActiveTrue()	… where x.active = true
False	findByActiveFalse()	… where x.active = false
IgnoreCase	findByFirstnameIgnoreCase	… where UPPER(x.firstame) = UPPER(?1)

好了废话了这么多直接上代码：

1.首先我们需要定义一个实体Person:

package com.fxr.springdata;

import java.util.Date;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

@Table(name="JPA_PERSONS")
@Entity
public class Person {

	private Integer id;
	private String lastName;
	private String email;
	private Date birth;
	@GeneratedValue
	@Id
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	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 Date getBirth() {
		return birth;
	}
	public void setBirth(Date birth) {
		this.birth = birth;
	}
	@Override
	public String toString() {
		return "Person [id=" + id + ", lastName=" + lastName + ", email="
				+ email + ", birth=" + birth + "]";
	}

}

　　2.我们需要写一个PersonRepsotory接口来实现JpaRepository<Person,Integer>，传的两个泛型第一个是实体类，第二个是主键的类型

package com.fxr.springdata;

import org.springframework.data.jpa.repository.JpaRepository;

public interface PersonRepsotory extends JpaRepository<Person,Integer>{

	//根据lastName来获取对应的Person
	Person getByLastName(String lastName);

}

　　3.编写测试类

package com.fxr.test;

import java.sql.SQLException;

import javax.sql.DataSource;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.fxr.springdata.Person;
import com.fxr.springdata.PersonRepsotory;

public class SpringDataTest {

	private ApplicationContext ctx = null;
	private PersonRepsotory personRepsotory;

	{
		ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
		personRepsotory = ctx.getBean(PersonRepsotory.class);
	}

	//测试配置的数据源成功没有成功
	@Test
	public void testDataSource() throws SQLException{
		DataSource dataSource = ctx.getBean(DataSource.class);
		System.out.println(dataSource.getConnection());
	}

	@Test
	public void testHelloWorldSpringData(){
		System.out.println(personRepsotory.getClass().getName());

		Person person = personRepsotory.getByLastName("sunwukong");
		System.out.println(person);
	}

}

　　打印出结果，就说明我们的程序运行成功