Spring Data JPA使用复合主键

演示环境

MySQL 5.7

JDK1.8

spring-data-jpa 1.10.4.RELEASE

hibernate 5.1.2.Final

这里演示一个余额宝的例子，一个用户一天一条记录，表示一个用户一天的收益情况。其中，用户ID，日期是复合主键

项目总体结构如下：

下面依次贴出源代码

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>com.pp.jpa</groupId>
	<artifactId>springdata-jpa</artifactId>
	<version>1.0.0</version>
	<packaging>jar</packaging>

	<name>springdata-jpa</name>
	<url>http://maven.apache.org</url>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<maven.compiler.source>1.8</maven.compiler.source>
		<maven.compiler.target>1.8</maven.compiler.target>
	</properties>

	<dependencies>
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>5.1.40</version>
		</dependency>
		<dependency>
			<groupId>org.springframework.data</groupId>
			<artifactId>spring-data-jpa</artifactId>
			<version>1.10.4.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-core</artifactId>
			<version>5.1.2.Final</version>
		</dependency>
		<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-entitymanager</artifactId>
			<version>5.1.2.Final</version>
		</dependency>
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>4.12</version>
			<scope>test</scope>
		</dependency>
	</dependencies>

</project>

下面依次是Java源码

package com.pp.jpa.config;

import javax.persistence.EntityManagerFactory;
import javax.sql.DataSource;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;

import com.mysql.jdbc.jdbc2.optional.MysqlDataSource;

@Configuration
public class JPAConfiguration {

	@Bean
	public DataSource createDataSource(){
		MysqlDataSource ds = new MysqlDataSource();
		ds.setURL("jdbc:mysql://127.0.0.1:3306/jpa");
		ds.setUser("root");
		ds.setPassword("admin123");
		return ds;
	}
	
	@Bean(name="entityManagerFactory")
	public EntityManagerFactory createEntityManagerFactory(DataSource dataSource){
		LocalContainerEntityManagerFactoryBean entityManagerFactory = new LocalContainerEntityManagerFactoryBean();
		entityManagerFactory.setDataSource(dataSource);
		
		HibernateJpaVendorAdapter jpaVendorAdapter = new HibernateJpaVendorAdapter();
		jpaVendorAdapter.setGenerateDdl(true);
		jpaVendorAdapter.setShowSql(true);
		entityManagerFactory.setPackagesToScan("com.pp.jpa.entity");
		entityManagerFactory.setJpaVendorAdapter(jpaVendorAdapter);
		entityManagerFactory.afterPropertiesSet();
		return entityManagerFactory.getObject();
	}
	
	@Bean(name="transactionManager")
	public PlatformTransactionManager createPlatformTransactionManager(EntityManagerFactory entityManagerFactory){
		JpaTransactionManager transactionManager = new JpaTransactionManager();
		transactionManager.setEntityManagerFactory(entityManagerFactory);
		return transactionManager;
	}
}

package com.pp.jpa.entity;

import java.io.Serializable;

import javax.persistence.Embeddable;

/**
 * 主键 
 * 代表复合主键的实体bean需要实现Serializable接口
 */
@Embeddable
public class UserFundPrimarykey implements Serializable {
	
	private static final long serialVersionUID = 1L;

	//用户ID
	private Integer userId;
	
	/**
	 * 日期，格式yyyy-MM-dd
	 */
	private String date;
	
	public UserFundPrimarykey() {}
	
	public UserFundPrimarykey(Integer userId, String date) {
		this.userId = userId;
		this.date = date;
	}

	public Integer getUserId() {
		return userId;
	}

	public void setUserId(Integer userId) {
		this.userId = userId;
	}

	public String getDate() {
		return date;
	}

	public void setDate(String date) {
		this.date = date;
	}

	@Override
	public String toString() {
		return "UserFundPrimarykey [userId=" + userId + ", date=" + date + "]";
	}
}

package com.pp.jpa.entity;

import java.math.BigDecimal;

import javax.persistence.Column;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.Table;

/**
 *  模拟一个余额宝的功能
 *  一条记录代表一个用户一天的收益信息（本金，利率，利息）
 */
@Entity
@Table(name = "user_funds")
public class UserFund {
	
	/**
	 * 主键
	 * 复合主键不能用@Id，需要用@EmbeddedId。插入数据的时候必须手工赋值
	 */
	@EmbeddedId
	private UserFundPrimarykey userFundPK;
	
	//本金
	@Column(precision=18, scale=5)
	private BigDecimal principal;
	
	//利率（5%传0.05）
	@Column(precision=18, scale=5)
	private BigDecimal rate;
	
	/**
	 * 当天收益（日利息=本金*利率/365）
	 * 保留2位小数
	 */
	@Column(precision=18, scale=2)
	private BigDecimal interest;

	public UserFundPrimarykey getUserFundPK() {
		return userFundPK;
	}

	public void setUserFundPK(UserFundPrimarykey userFundPK) {
		this.userFundPK = userFundPK;
	}

	public BigDecimal getPrincipal() {
		return principal;
	}

	public void setPrincipal(BigDecimal principal) {
		this.principal = principal;
	}

	public BigDecimal getRate() {
		return rate;
	}

	public void setRate(BigDecimal rate) {
		this.rate = rate;
	}

	public BigDecimal getInterest() {
		return interest;
	}

	public void setInterest(BigDecimal interest) {
		this.interest = interest;
	}

	@Override
	public String toString() {
		return "UserFund [userFundPK=" + userFundPK + ", principal=" + principal + ", rate=" + rate + ", interest="
				+ interest + "]";
	}
}

package com.pp.repository;

import org.springframework.data.repository.CrudRepository;

import com.pp.jpa.entity.UserFund;
import com.pp.jpa.entity.UserFundPrimarykey;

public interface UserFundRepository extends CrudRepository<UserFund, UserFundPrimarykey> {
	
} 

启动类

package com.pp.jpa;

import java.math.BigDecimal;
import java.math.RoundingMode;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import com.pp.jpa.entity.UserFund;
import com.pp.jpa.entity.UserFundPrimarykey;
import com.pp.repository.UserFundRepository;

@ComponentScan
@EnableJpaRepositories(value="com.pp")
@EnableTransactionManagement
public class App {
	public static void main(String[] args) throws Exception {
		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(App.class);
		
		UserFund uf1 = new UserFund();
		//必须手动设置主键
		uf1.setUserFundPK(new UserFundPrimarykey(1, "2017-07-01"));
		uf1.setRate(new BigDecimal("0.041"));
		uf1.setPrincipal(new BigDecimal("10000"));
		//截断，只保留两位小数
		uf1.setInterest(uf1.getRate().multiply(uf1.getPrincipal()).divide(new BigDecimal("365"), 2, RoundingMode.DOWN));
		
		UserFund uf2 = new UserFund();
		//必须手动设置主键
		uf2.setUserFundPK(new UserFundPrimarykey(2, "2017-07-01"));
		uf2.setRate(new BigDecimal("0.041"));
		uf2.setPrincipal(new BigDecimal("20000"));
		//截断，只保留两位小数
		uf2.setInterest(uf2.getRate().multiply(uf2.getPrincipal()).divide(new BigDecimal("365"), 2, RoundingMode.DOWN));
		
		UserFundRepository ur = context.getBean(UserFundRepository.class);
		ur.save(uf1);
		ur.save(uf2);
		
		ur.findAll().forEach(System.out::println);
		
		//查询用户ID=2，在2017-07-01这一天的收益
		System.out.println(ur.findOne(new UserFundPrimarykey(2, "2017-07-01")));
		context.close();
	}
}

一些注意事项和做法已经在备注中有写，大家模仿着写就OK了

直接运行main方法，控制台输出如下信息

Hibernate: select userfund0_.date as date1_0_0_, userfund0_.userId as userId2_0_0_, userfund0_.interest as interest3_0_0_, userfund0_.principal as principa4_0_0_, userfund0_.rate as rate5_0_0_ from user_funds userfund0_ where userfund0_.date=? and userfund0_.userId=?
Hibernate: insert into user_funds (interest, principal, rate, date, userId) values (?, ?, ?, ?, ?)
Hibernate: select userfund0_.date as date1_0_0_, userfund0_.userId as userId2_0_0_, userfund0_.interest as interest3_0_0_, userfund0_.principal as principa4_0_0_, userfund0_.rate as rate5_0_0_ from user_funds userfund0_ where userfund0_.date=? and userfund0_.userId=?
Hibernate: insert into user_funds (interest, principal, rate, date, userId) values (?, ?, ?, ?, ?)
Hibernate: select userfund0_.date as date1_0_, userfund0_.userId as userId2_0_, userfund0_.interest as interest3_0_, userfund0_.principal as principa4_0_, userfund0_.rate as rate5_0_ from user_funds userfund0_
UserFund [userFundPK=UserFundPrimarykey [userId=1, date=2017-07-01], principal=10000.00000, rate=0.04100, interest=1.12]
UserFund [userFundPK=UserFundPrimarykey [userId=2, date=2017-07-01], principal=20000.00000, rate=0.04100, interest=2.24]
Hibernate: select userfund0_.date as date1_0_0_, userfund0_.userId as userId2_0_0_, userfund0_.interest as interest3_0_0_, userfund0_.principal as principa4_0_0_, userfund0_.rate as rate5_0_0_ from user_funds userfund0_ where userfund0_.date=? and userfund0_.userId=?
UserFund [userFundPK=UserFundPrimarykey [userId=2, date=2017-07-01], principal=20000.00000, rate=0.04100, interest=2.24]

查询数据库

select ** from user_funds;

最后说一句，余额宝的利息好低啊，一万块钱存一天，只有1块钱左右