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