在spring boot项目中使用Spring Boot Jpa 通过Druid配置多数据源、文章末尾对比Hakari连接池。
Spring Boot Jpa 介绍
首先了解 Jpa 是什么？
Jpa (Java Persistence API) 是 Sun 官方提出的 Java 持久化规范。它为 Java 开发人员提供了一种对象/关联映射工具来管理 Java 应用中的关系数据。它的出现主要是为了简化现有的持久化开发工作和整合 ORM 技术，结束现在 Hibernate，TopLink，JDO 等 ORM 框架各自为营的局面。
值得注意的是，Jpa是在充分吸收了现有 Hibernate，TopLink，JDO 等 ORM 框架的基础上发展而来的，具有易于使用，伸缩性强等优点。从目前的开发社区的反应上看，Jpa 受到了极大的支持和赞扬，其中就包括了 Spring 与 EJB3. 0的开发团队。
注意:Jpa 是一套规范，不是一套产品，那么像 Hibernate,TopLink,JDO 他们是一套产品，如果说这些产品实现了这个 Jpa 规范，那么我们就可以叫他们为 Jpa 的实现产品。
Spring Boot Jpa
Spring Boot Jpa 是 Spring 基于 ORM 框架、Jpa 规范的基础上封装的一套 Jpa 应用框架，可使开发者用极简的代码即可实现对数据的访问和操作。它提供了包括增删改查等在内的常用功能，且易于扩展！学习并使用 Spring Data Jpa 可以极大提高开发效率！
Spring Boot Jpa 让我们解脱了 DAO 层的操作，基本上所有 CRUD 都可以依赖于它来实现
基本查询
基本查询也分为两种，一种是 Spring Data 默认已经实现，一种是根据查询的方法来自动解析成 SQL。
预先生成方法
Spring Boot Jpa 默认预先生成了一些基本的CURD的方法，例如：增、删、改等等
继承 JpaRepository
public interface UserRepository extends JpaRepository {
} 一 我们使用首先要引入spring data jpa 的jar包
org.springframework.boot
spring-boot-starter-data-jpa
org.slf4j
jcl-over-slf4j
也要引入druid的jar包
com.alibaba
druid
1.1.10
二、要在 application.properties 配置文件中配置两个数据源的一些信息
#first datasource
spring.datasource.first.url=jdbc:oracle:thin:@//ip1:1521/ORCL
spring.datasource.first.username=name1
spring.datasource.first.password=password1
spring.datasource.first.driverClassName=oracle.jdbc.driver.OracleDriver
spring.datasource.first.test-while-idle=true
spring.datasource.first.test-on-borrow=false
spring.datasource.first.test-on-return=false
spring.datasource.first.validation-query=SELECT 1 FROM DUAL
spring.datasource.first.time-between-eviction-runs-millis=300000
spring.datasource.first.min-evictable-idle-time-millis=1800000
spring.datasource.first.initial-size=5
spring.datasource.first.max-active=50
spring.datasource.first.max-wait=60000
spring.datasource.first.min-idle=5
#second datasource
spring.datasource.second.url=jdbc:oracle:thin:@//ip2:1521/ORCL
spring.datasource.second.username=name2
spring.datasource.second.password=password2
spring.datasource.second.driverClassName=oracle.jdbc.driver.OracleDriver
spring.datasource.second.test-while-idle=true
spring.datasource.second.test-on-borrow=false
spring.datasource.second.test-on-return=false
spring.datasource.second.validation-query=SELECT 1 FROM DUAL
spring.datasource.second.time-between-eviction-runs-millis=300000
spring.datasource.second.min-evictable-idle-time-millis=1800000
spring.datasource.second.initial-size=5
spring.datasource.second.max-active=50
spring.datasource.second.max-wait=60000
spring.datasource.second.min-idle=5三、开始配置第一数据源也就是第一数据源也就是主数据源
1、配置dataSource的FirstDataSourceConfig类
import javax.sql.DataSource;
import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.jdbc.core.JdbcTemplate;
@Configuration
public class FirstDataSourceConfig {
@Bean(name = {"firstDataSource"})
@Qualifier("firstDataSource")
@ConfigurationProperties(prefix = "spring.datasource.first")
@Primary
public DataSource firstDataSource() {
return DataSourceBuilder.create().type(com.alibaba.druid.pool.DruidDataSource.class).build();
}
/* public DruidDataSource firstDataSource(){
return new DruidDataSource();
}*/
@Bean(name = {"jdbcTemplateDmdb"})
@Primary
public JdbcTemplate jdbcTemplate(@Qualifier("firstDataSource") DataSource dataSource) {
return new JdbcTemplate(dataSource);
}
}
2、配置jpa的 repository文件
import java.util.Map;
import javax.persistence.EntityManager;
import javax.sql.DataSource;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.orm.jpa.JpaProperties;
import org.springframework.boot.orm.jpa.EntityManagerFactoryBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;
@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
entityManagerFactoryRef = "entityManagerFactoryFirst",
transactionManagerRef = "transactionManagerFirst",
basePackages = {"cn.com.repository"}) //repository所在包的位置
public class RepositoryFirstConfig {
@Autowired
private JpaProperties jpaProperties;
@Autowired
@Qualifier("firstDataSource")
private DataSource firstDS;
@Bean(name = "entityManagerFirst")
@Primary
public EntityManager entityManagerFirst(EntityManagerFactoryBuilder builder) {
return entityManagerFactorySecondary(builder).getObject().createEntityManager();
}
@Bean(name = "entityManagerFactoryFirst")
@Primary
public LocalContainerEntityManagerFactoryBean entityManagerFactoryFirst(EntityManagerFactoryBuilder builder) {
return builder
.dataSource(firstDS)
.properties(getVendorProperties(firstDS))
.packages("cn.com.domain") //domain所在包的位置
.persistenceUnit("firstPersistenceUnit")
.build();
}
private Map getVendorProperties(DataSource dataSource) {
return jpaProperties.getHibernateProperties(dataSource);
}
@Bean(name = "transactionManagerFirst")
@Primary
PlatformTransactionManager transactionManagerFirst(EntityManagerFactoryBuilder builder) {
return new JpaTransactionManager(entityManagerFactoryFirst(builder).getObject());
}
} 四、配置第二数据源信息
1、配置dataSource的SecondDataSourceConfig类
import javax.sql.DataSource;
import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.jdbc.core.JdbcTemplate;
@Configuration
public class SecondDataSourceConfig {
@Bean(name = {"secondaryDataSource"})
@Qualifier("secondaryDataSource")
@ConfigurationProperties(prefix = "spring.datasource.second")
public DataSource secondaryDataSource() {
return DataSourceBuilder.create().type(com.alibaba.druid.pool.DruidDataSource.class).build();
}
/* public DruidDataSource secondaryDataSource(){
return new DruidDataSource();
}*/
@Bean(name = {"jdbcTemplateDmdb"})
public JdbcTemplate jdbcTemplate(@Qualifier("secondaryDataSource") DataSource dataSource) {
return new JdbcTemplate(dataSource);
}
}2、配置jpa的 repository文件
import java.util.Map;
import javax.persistence.EntityManager;
import javax.sql.DataSource;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.orm.jpa.JpaProperties;
import org.springframework.boot.orm.jpa.EntityManagerFactoryBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;
@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
entityManagerFactoryRef = "entityManagerFactorySecondary",
transactionManagerRef = "transactionManagerSecondary",
basePackages = {"cn.com.repository2"}) //repository所在包的位置
public class RepositorySecondaryConfig {
@Autowired
private JpaProperties jpaProperties;
@Autowired
@Qualifier("secondaryDataSource")
private DataSource secondaryDS;
@Bean(name = "entityManagerSecondary")
public EntityManager entityManager(EntityManagerFactoryBuilder builder) {
return entityManagerFactorySecondary(builder).getObject().createEntityManager();
}
@Bean(name = "entityManagerFactorySecondary")
public LocalContainerEntityManagerFactoryBean entityManagerFactorySecondary(EntityManagerFactoryBuilder builder) {
return builder
.dataSource(secondaryDS)
.properties(getVendorProperties(secondaryDS))
.packages("cn.com.domain2") //domain所在包的位置
.persistenceUnit("secondaryPersistenceUnit")
.build();
}
private Map getVendorProperties(DataSource dataSource) {
return jpaProperties.getHibernateProperties(dataSource);
}
@Bean(name = "transactionManagerSecondary")
PlatformTransactionManager transactionManagerSecondary(EntityManagerFactoryBuilder builder) {
return new JpaTransactionManager(entityManagerFactorySecondary(builder).getObject());
}
} 五、到此多数据源已经都配置好了，如果需要配置更多数据源以此类推。需要注意的是spring boot jpa 的repository文件配置扫描的包要配置好（repository所在包的位置、domain所在包的位置），不然的话这个数据源在你想要的的作用域是不起作用的。
六、如果我想直接用hibernate的sessionFactory原生的语句查询
1、首先配置hibernate的session新建一个类在需要的类继续此类就行
package cn.com.xxx.common;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
public abstract class MyHibernateDaoSupport {
private static final Logger log = LoggerFactory.getLogger(MyHibernateDaoSupport.class);
private Session session;
@Autowired
private SessionFactory sessionFactory;
private void startOperation() {
try {
session = sessionFactory.openSession();
} catch (Exception e) {
log.error("获取 Hibernate Session 异常", e);
}
}
protected void closeSession() {
if (session != null) {
try {
session.close();
} catch (Exception e) {
log.error("关闭 Hibernate Session 异常", e);
}
}
}
protected Session getSession() throws HibernateException {
if (this.session == null || !this.session.isOpen()) {
startOperation();
}
return session;
}
}
2、springboot配置加载sessionFactory的数据源、咱们已第二数据源为列新建一个配置类
import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import javax.persistence.EntityManagerFactory;
@Configuration
public class HibernateConfig {
/**
* entityManagerFactorySecondary 要选择第二数据源的entityManagerFactory
* @param emf
* @return
*/
@Bean
public SessionFactory sessionFactory(@Qualifier("entityManagerFactorySecondary") EntityManagerFactory emf) {
return emf.unwrap(SessionFactory.class);
}
}3、直接就可以在类中使用session来sql语句操作了
public class DataServiceImpl extends MyHibernateDaoSupport{
@Override
public void getClassDropDown() {
try {
Map map = new HashMap();
List arrayList = new ArrayList();
String sql = "SELECT FLDNAME FROM TABLENAME WHERE FLDNAME IS NOT
NULL GROUP BY FLDNAME ";
SQLQuery sqlQuery = getSession().createSQLQuery(sql);
List listObj = sqlQuery.list();
} catch (Exception e) {
log.error("异常" + e);
} finally {
closeSession();
}
}
} 现在很多druid数据库连接池但是我在网上看到的性能问题是Hakari要比druid好很多，我也没验证过不知道真假在此看到一个网友关于Hakari配置多数据的拿来和Druid多数据源配置对比一下。springBoot1.x版本的数据库连接池不是Hakari，在springBoot2.0版本以后才默认是Hakari。文章链接