隨著Springboot升級到2.0，原來1.5.x的Jpa多資料來源配置不能用了。現在總結一下Springboot2.0的jpa多資料來源配置

連線池還是用druid，但是不能用druid的starter了，譬如在1.5.x時用的是

<dependency>
			<groupId>com.alibaba</groupId>
			<artifactId>druid-spring-boot-starter</artifactId>
			<version>1.1.6</version>
		</dependency>
 

<dependency>
			<groupId>com.alibaba</groupId>
			<artifactId>druid</artifactId>
			<version>1.1.6</version>
		</dependency>
		<dependency>
			<groupId>log4j</groupId>
			<artifactId>log4j</artifactId>
			<version>1.2.17</version>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
 

application.yml也有變化

原來是這樣的

spring:
  jpa:
    database: mysql
    show-sql: true
    hibernate:
      ddl-auto: update
      naming:
        strategy: org.hibernate.cfg.ImprovedNamingStrategy #命名策略，加分隔線"_"

spring:
  datasource:
    primary:
      url: jdbc:mysql://localhost:3306/company?autoReconnect=true&useUnicode=true
      username: root
      password: root
    secondary:
      url: jdbc:mysql://localhost:3306/com1?autoReconnect=true&useUnicode=true
      username: root
      password: root
  jpa:
    database: mysql
    generate-ddl: true
    show-sql: true
    hibernate:
      ddl-auto: update
      naming:
        physical-strategy: org.springframework.boot.orm.jpa.hibernate.SpringPhysicalNamingStrategy
 

先來配置druid的DataSource，這個類在新老版本里都能用，不需要變化。

package com.example.demo.druid;

import com.alibaba.druid.pool.DruidDataSource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.web.servlet.ServletComponentScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;

import javax.sql.DataSource;
import java.sql.SQLException;

/**
 * @author wuweifeng wrote on 2017/10/23.
 * 資料庫連線屬性配置
 */
@ServletComponentScan
@Configuration
public class DruidDBConfig {
    private Logger logger = LoggerFactory.getLogger(DruidDBConfig.class);

    @Value("${spring.datasource.primary.url}")
    private String dbUrl1;

    @Value("${spring.datasource.primary.username}")
    private String username1;

    @Value("${spring.datasource.primary.password}")
    private String password1;

    @Value("${spring.datasource.secondary.username}")
    private String username2;

    @Value("${spring.datasource.secondary.password}")
    private String password2;

    @Value("${spring.datasource.secondary.url}")
    private String dbUrl2;

    @Value("com.mysql.jdbc.Driver")
    private String driverClassName;

    @Value("5")
    private int initialSize;

    @Value("5")
    private int minIdle;

    @Value("20")
    private int maxActive;

    @Value("60000")
    private int maxWait;

    /**
     * 配置間隔多久才進行一次檢測，檢測需要關閉的空閒連線，單位是毫秒
     */
    @Value("60000")
    private int timeBetweenEvictionRunsMillis;
    /**
     * 配置一個連線在池中最小生存的時間，單位是毫秒
     */
    @Value("300000")
    private int minEvictableIdleTimeMillis;

    @Value("SELECT 1 FROM DUAL")
    private String validationQuery;

    @Value("true")
    private boolean testWhileIdle;

    @Value("false")
    private boolean testOnBorrow;

    @Value("false")
    private boolean testOnReturn;

    /**
     * 開啟PSCache，並且指定每個連線上PSCache的大小
     */
    @Value("true")
    private boolean poolPreparedStatements;

    @Value("20")
    private int maxPoolPreparedStatementPerConnectionSize;
    /**
     * 配置監控統計攔截的filters，去掉後監控介面sql無法統計，'wall'用於防火牆
     */
    @Value("stat,wall,log4j")
    private String filters;
    /**
     * 通過connectProperties屬性來開啟mergeSql功能；慢SQL記錄
     */
    @Value("druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500")
    private String connectionProperties;

    @Bean(name = "primaryDataSource")
    @Qualifier("primaryDataSource")
    public DataSource dataSource() {
        return getDruidDataSource(username1, password1, dbUrl1);
    }

    @Bean(name = "secondaryDataSource")
    @Qualifier("secondaryDataSource")
    @Primary
    public DataSource secondaryDataSource() {
        return getDruidDataSource(username2, password2, dbUrl2);
    }

    private DruidDataSource getDruidDataSource(String username, String password, String url) {
        DruidDataSource datasource = new DruidDataSource();

        datasource.setUrl(url);
        datasource.setUsername(username);
        datasource.setPassword(password);
        datasource.setDriverClassName(driverClassName);

        //configuration
        datasource.setInitialSize(initialSize);
        datasource.setMinIdle(minIdle);
        datasource.setMaxActive(maxActive);
        datasource.setMaxWait(maxWait);
        datasource.setTimeBetweenEvictionRunsMillis(timeBetweenEvictionRunsMillis);
        datasource.setMinEvictableIdleTimeMillis(minEvictableIdleTimeMillis);
        datasource.setValidationQuery(validationQuery);
        datasource.setTestWhileIdle(testWhileIdle);
        datasource.setTestOnBorrow(testOnBorrow);
        datasource.setTestOnReturn(testOnReturn);
        datasource.setPoolPreparedStatements(poolPreparedStatements);
        datasource.setMaxPoolPreparedStatementPerConnectionSize(maxPoolPreparedStatementPerConnectionSize);
        try {
            datasource.setFilters(filters);
        } catch (SQLException e) {
            logger.error("druid configuration initialization filter : {0}", e);
        }
        datasource.setConnectionProperties(connectionProperties);

        return datasource;
    }
}

第一資料來源：

package com.example.demo.druid;

import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.orm.jpa.HibernateSettings;
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.context.annotation.Primary;
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;

import javax.annotation.Resource;
import javax.persistence.EntityManager;
import javax.sql.DataSource;
import java.util.Map;

/**
 * @author wuweifeng wrote on 2017/10/31.
 */
@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
        entityManagerFactoryRef = "entityManagerFactoryPrimary",
        transactionManagerRef = "transactionManagerPrimary",
        basePackages = {"com.example.demo.repository.primary"})
public class PrimaryConfig {

    @Resource
    @Qualifier("primaryDataSource")
    private DataSource primaryDataSource;

    @Primary
    @Bean(name = "entityManagerPrimary")
    public EntityManager entityManager(EntityManagerFactoryBuilder builder) {
        return entityManagerFactoryPrimary(builder).getObject().createEntityManager();
    }

    @Resource
    private JpaProperties jpaProperties;

    private Map<String, Object> getVendorProperties() {
        return jpaProperties.getHibernateProperties(new HibernateSettings());
    }

    /**
     * 設定實體類所在位置
     */
    @Primary
    @Bean(name = "entityManagerFactoryPrimary")
    public LocalContainerEntityManagerFactoryBean entityManagerFactoryPrimary(EntityManagerFactoryBuilder builder) {
        return builder
                .dataSource(primaryDataSource)
                .packages("com.example.demo.model.primary")
                .persistenceUnit("primaryPersistenceUnit")
                .properties(getVendorProperties())
                .build();
    }

    @Primary
    @Bean(name = "transactionManagerPrimary")
    public PlatformTransactionManager transactionManagerPrimary(EntityManagerFactoryBuilder builder) {
        return new JpaTransactionManager(entityManagerFactoryPrimary(builder).getObject());
    }

}

package com.example.demo.druid;

import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.orm.jpa.HibernateSettings;
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;

import javax.annotation.Resource;
import javax.persistence.EntityManager;
import javax.sql.DataSource;
import java.util.Map;

/**
 * @author by wuweifeng on 2017/10/10.
 */
@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
        entityManagerFactoryRef = "entityManagerFactorySecondary",
        transactionManagerRef = "transactionManagerSecondary",
        basePackages = {"com.example.demo.repository.secondary"})
public class SecondaryConfig {

    @Resource
    @Qualifier("secondaryDataSource")
    private DataSource secondaryDataSource;

    @Bean(name = "entityManagerSecondary")
    public EntityManager entityManager(EntityManagerFactoryBuilder builder) {
        return entityManagerFactorySecondary(builder).getObject().createEntityManager();
    }

    @Resource
    private JpaProperties jpaProperties;

    private Map<String, Object> getVendorProperties() {
        return jpaProperties.getHibernateProperties(new HibernateSettings());
    }

    @Bean(name = "entityManagerFactorySecondary")
    public LocalContainerEntityManagerFactoryBean entityManagerFactorySecondary(EntityManagerFactoryBuilder builder) {
        return builder
                .dataSource(secondaryDataSource)
                .packages("com.example.demo.model.secondary")
                .persistenceUnit("secondaryPersistenceUnit")
                .properties(getVendorProperties())
                .build();
    }

    @Bean(name = "transactionManagerSecondary")
    PlatformTransactionManager transactionManagerSecondary(EntityManagerFactoryBuilder builder) {
        return new JpaTransactionManager(entityManagerFactorySecondary(builder).getObject());
    }

}

它與1.5.x版本的主要區別在於getVerdorProperties這個方法，原來的getHibernateProperties是傳引數DataSource，現在是傳引數HibernateSettings，

HibernateSettings類其實就是配置列名生成策略的，我們已經在yml裡配置過了，這裡直接new 一個空類過去就行了。

這樣我們就完成了Springboot 2.0.0.M7的多資料來源Jpa配置了。

還有一個地方需要提一下，Springboot2.0依賴了Hibernate5.2版本，1.5.x依賴的是Hibernate5.0.12版本，這兩個版本在處理Id自增方面是不一樣的。

在老版本里，我們定義了

 @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id")
    public Long getId() {
        return id;
    }

在新版本里，Auto是不行的，不會自增，而且Hibernate會額外創建出來一個表來專門維護Id。可以自行嘗試一下，會多出來一個表。

我們如果需要自增的Id，需要顯式指定

@Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    public Long getId() {
        return id;
    }