Spring Data JPA是Spring基于Hibernate开发的一个JPA框架。如果用过Hibernate或者MyBatis的话，就会知道对象关系映射（ORM）框架有多么方便。
但是Spring Data JPA框架功能更进一步，为我们做了 一个数据持久层框架几乎能做的任何事情。下面来逐步介绍它的强大功能。
直接上代码：
pom.xml
<!-- hibernate start -->
<!-- spring data jpa -->
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-jpa</artifactId>
<version>2.1.3.RELEASE</version>
</dependency>
<!-- hibernate -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>5.4.0.Final</version>
</dependency>
<!-- hibernate end -->
项目结构：
the_data_jpa 包 里面的 各类 代码
User
package com.oukele.the_data_jpa.entity;
import org.springframework.stereotype.Component;
import javax.persistence.*;
@Entity
@Table(name = "user")
public class User {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "Id")
private int id;
@Column(name = "userName")
private String name;
private String password;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
UserDao
package com.oukele.the_data_jpa.dao;
import com.oukele.the_data_jpa.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;
import java.util.List;
public interface UserDao extends JpaRepository<User, Integer> {
User findByNameAndPassword(String name,String password);
}
UserService
package com.oukele.the_data_jpa.service;
import com.oukele.the_data_jpa.dao.UserDao;
import com.oukele.the_data_jpa.entity.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.jpa.repository.Query;
import org.springframework.stereotype.Service;
import java.util.List;
@Service
public class UserService {
@Autowired
private UserDao userDao;
public User findNameAndPassword(String name,String password){
return userDao.findByNameAndPassword(name, password);
}
public List<User> list(){
List<User> list = userDao.findAll();
return list;
}
}
SpringConfig
package com.oukele.the_data_jpa;
import com.mchange.v2.c3p0.ComboPooledDataSource;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.core.env.Environment;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;
import javax.sql.DataSource;
import java.beans.PropertyVetoException;
import java.util.Properties;
@Configuration//声明当前配置类
@ComponentScan(basePackages = "com.oukele.the_data_jpa")// 扫描当前包 使用 spring 注解
@PropertySource("classpath:jdbc.properties")//加载 资源文件
@EnableJpaRepositories(basePackages = "com.oukele.the_data_jpa.dao")//扫描 使用 jpa 注解的接口
public class SpringConfig {
//配置数据源
@Bean
DataSource dataSource(Environment env) throws PropertyVetoException {
ComboPooledDataSource dataSource = new ComboPooledDataSource();
dataSource.setDriverClass(env.getProperty("jdbc.driver"));
dataSource.setJdbcUrl(env.getProperty("jdbc.url"));
dataSource.setUser(env.getProperty("jdbc.user"));
dataSource.setPassword(env.getProperty("jdbc.password"));
return dataSource;
}
// @Bean
// public JdbcTemplate jdbcTemplate() {
// JdbcTemplate jdbcTemplate = new JdbcTemplate();
// jdbcTemplate.setDataSource(dataSource1);
// return jdbcTemplate;
// }
@Bean
public PlatformTransactionManager transactionManager(DataSource dataSource) {
return new DataSourceTransactionManager(dataSource);
}
//SqlSessionFactory
@Bean
LocalContainerEntityManagerFactoryBean entityManagerFactory(DataSource dataSource){
LocalContainerEntityManagerFactoryBean bean = new LocalContainerEntityManagerFactoryBean();
bean.setDataSource(dataSource);
//加载 实体类
bean.setPackagesToScan("com.oukele.the_data_jpa.entity");
//设置 适配器
bean.setJpaVendorAdapter(new HibernateJpaVendorAdapter());
Properties properties = new Properties();
//更新表结构
properties.setProperty("hibernate.hbm2ddl.auto", "update");
//设置方言
properties.setProperty("hibernate.dialect", "org.hibernate.dialect.MySQLDialect");
bean.setJpaProperties(properties);
return bean;
}
}
Main ( 测试 类)
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package com.oukele.the_data_jpa;
import com.oukele.the_data_jpa.entity.User;
import com.oukele.the_data_jpa.service.UserService;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import java.util.List;
public class Main {
public static void main(String[] args) {
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);
UserService service = context.getBean(UserService.class);
User user = service.findNameAndPassword("oukele","oukele");
System.out.println(user.getName());
List<
User
> list = service.list();
for (User user1 : list) {
System.out.println(user1.getName()+" - "+user1.getPassword());
}
}
}
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测试结果：
1 oukele 2 oukele - oukele
jdbc.properties文件：
jdbc.driver=org.mariadb.jdbc.Driver jdbc.url=jdbc:mariadb://localhost:3306/test jdbc.user=oukele jdbc.password=oukele