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六、spring boot 配置多数据源

spring boot 已经支持多数据源配置了,无需网上好多那些编写什么类的,特别麻烦,看看如下解决方案,官方的,放心!

 

1.首先定义数据源配置

#=====================multiple database config============================
#ds1
first.datasource.url=jdbc:mysql://localhost/test?characterEncoding=utf8&useSSL=true
first.datasource.username=root
first.datasource.password=123456
first.datasource.driver-class-name=com.mysql.jdbc.Driver
first.datasource.type=org.apache.tomcat.jdbc.pool.DataSource
first.datasource.max-wait=10000
first.datasource.max-active=200
first.datasource.test-on-borrow=true
first.datasource.initial-size=10

#ds2
second.datasource.url=jdbc:mysql://localhost/test2?characterEncoding=utf8&useSSL=true
second.datasource.username=root
second.datasource.password=123456
second.datasource.driver-class-name=com.mysql.jdbc.Driver
second.datasource.type=org.apache.tomcat.jdbc.pool.DataSource
second.datasource.max-wait=10000
second.datasource.max-active=200
second.datasource.test-on-borrow=true
second.datasource.initial-size=10

#=====================jpa config================================
#实体类维护数据库表结构的具体行为:update/create/create-drop/validate/none
spring.jpa.hibernate.ddl-auto=none
#打印sql语句
spring.jpa.show-sql=true
#格式化输出的json字符串
spring.jackson.serialization.indent_output=true


2.配置ds1的相关注入对象和启用jpa支持
/**
 * Created by hdwang on 2017-06-16.
 * 第一个数据源配置
 * If you are using Spring Data, you need to configure @EnableJpaRepositories
 */
@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(basePackages = "com.hdwang.dao.datajpa.firstDs",entityManagerFactoryRef = "firstEntityManagerFactory",transactionManagerRef="firstTransactionManager")
public class FirstDsConfig {

    /**
     * 数据源配置对象
     * Primary 表示默认的对象,Autowire可注入,不是默认的得明确名称注入
     * @return
     */
    @Bean
    @Primary
    @ConfigurationProperties("first.datasource")
    public DataSourceProperties firstDataSourceProperties() {
        return new DataSourceProperties();
    }

    /**
     * 数据源对象
     * @return
     */
    @Bean
    @Primary
    @ConfigurationProperties("first.datasource")
    public DataSource firstDataSource() {
        return firstDataSourceProperties().initializeDataSourceBuilder().build();
    }

    /**
     * 实体管理对象
     * @param builder 由spring注入这个对象,首先根据type注入(多个就取声明@Primary的对象),否则根据name注入
     * @return
     */
    @Bean
    @Primary
    public LocalContainerEntityManagerFactoryBean firstEntityManagerFactory(
            EntityManagerFactoryBuilder builder) {
        return builder
                .dataSource(firstDataSource())
                .packages("com.hdwang.entity.dbFirst")
                .persistenceUnit("firstDs")
                .build();
    }

    /**
     * 事务管理对象
     * @return
     */
    @Bean(name = "firstTransactionManager")
    @Primary
    public PlatformTransactionManager transactionManager(EntityManagerFactory emf){
        JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(emf);
        return transactionManager;
    }

    @Bean
    @Primary
    public JdbcTemplate jdbcTemplate(){
        return new JdbcTemplate(firstDataSource());
    }

    @Bean
    @Primary
    public TransactionTemplate transactionTemplate(PlatformTransactionManager platformTransactionManager){
        return new TransactionTemplate(platformTransactionManager);
    }
}

 

相关知识点:
1.使用@Bean可以创建一个bean对象交给spring容器管理
2.@Bean创建的bean对象的名称默认为方法名,也可以指定
3.@Bean方法参数表示,接收一个bean对象,默认按照type类型接收注入的对象,若要修改为byName方式,可以使用@Qualifier注解注入准确的对象
4.@Primary表示该bean为此类型的默认bean,在其他地方引用的时候用@Autowired即可按照类型注入,不受同类型多个对象影响
5.EnableJpaRepositories表示启用spring data jpa的支持,也就是jpa的新使用方式,注意basePackages指的事 @Repository接口的所在包位置,可配置多个
其他注解就不清楚了!

2.配置ds2的相关注入对象和启用jpa支持
@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(basePackages = "com.hdwang.dao.datajpa.secondDs", entityManagerFactoryRef = "secondEntityManagerFactory",transactionManagerRef = "secondTransactionManager")
public class SecondDsConfig {

    @Bean
    @ConfigurationProperties("second.datasource")
    public DataSourceProperties secondDataSourceProperties() {
        return new DataSourceProperties();
    }

    @Bean
    @ConfigurationProperties("second.datasource")
    public DataSource secondDataSource() {
        return secondDataSourceProperties().initializeDataSourceBuilder().build();
    }

    /**
     * 实体管理对象
     * @param builder  由spring注入这个对象,首先根据type注入(多个就取声明@Primary的对象),否则根据name注入
     * @return
     */
    @Bean
    public LocalContainerEntityManagerFactoryBean secondEntityManagerFactory(
            EntityManagerFactoryBuilder builder) {
        return builder
                .dataSource(secondDataSource())
                .packages("com.hdwang.entity.dbSecond")
                .persistenceUnit("secondDs")
                .build();
    }

    /**
     * 事物管理对象
     * @param secondEntityManagerFactory 实体管理工厂对象(按照名称注入)
     * @return 平台事物管理器
     */
    @Bean(name = "secondTransactionManager")
    public PlatformTransactionManager transactionManager(@Qualifier("secondEntityManagerFactory")LocalContainerEntityManagerFactoryBean secondEntityManagerFactory){
        JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(secondEntityManagerFactory.getObject());
        return transactionManager;
    }

    @Bean(name="jdbcTemplate2")
    public JdbcTemplate jdbcTemplate(){
        return new JdbcTemplate(secondDataSource());
    }

    @Bean(name = "transactionTemplate2")
    public TransactionTemplate transactionTemplate(@Qualifier("secondTransactionManager")PlatformTransactionManager transactionManager){
        return new TransactionTemplate(transactionManager);
    }
}

 

 

3.Repository数据持久层

package com.hdwang.dao.datajpa.firstDs;

@Repository
public interface UserRepository extends JpaRepository<User, Integer> {
    /**
     * spring data jpa 会自动注入实现(根据方法命名规范)
     * @return
     */
    User findByNumber(String number);


    @Modifying
    @Query("delete from User u where u.id = :id")
    void deleteUser(@Param("id")int id);
}
package com.hdwang.dao.datajpa.secondDs;

@Repository
public interface OrderRepository extends JpaRepository<Order, Integer> {
    /**
     * spring data jpa 会自动注入实现(根据方法命名规范)
     * @return
     */
    User findByNumber(String number);


    @Modifying
    @Query("delete from Order o where o.id = :id")
    void deleteUser(@Param("id") int id);
}

 

上面两个接口分属两个数据源,在@EnableJpaRepositories配置好后,这里就可以正确操作相应的数据源了


4.Service服务层,注意事物(接口我就不贴了)
@Service
@Transactional("firstTransactionManager")
public class UserServiceImpl implements UserService {

    @Autowired
    private UserRepository userRepository;

    @Override
    public User findById(int id) {
        return this.userRepository.findOne(id);
    }

    @Override
    public User findByNumber(String number) {
        return this.userRepository.findByNumber(number);
    }

    @Override
    public List<User> findAllUserByPage(int page,int size) {
        Pageable pageable = new PageRequest(page, size);
        Page<User> users =  this.userRepository.findAll(pageable);
        return users.getContent();
    }

    @Override
    public User updateUser(User user,boolean throwEx) {
        User userNew = this.userRepository.save(user);
        if(throwEx){
            throw new RuntimeException("throw a ex");
        }
        return userNew;
    }

    @Override
    public void deleteUser(int id) {
        this.userRepository.deleteUser(id);
    }
}
@Service
@Transactional("secondTransactionManager")
public class OrderServiceImpl implements OrderService {

    @Autowired
    private OrderRepository orderRepository;


    @Override
    public Order findById(int id) {
        return this.orderRepository.findOne(id);
    }

    @Override
    public Order updateOrder(Order order, boolean throwEx) {
        Order orderNew = this.orderRepository.save(order);
        if(throwEx){
            throw new RuntimeException("throw a ex");
        }
        return orderNew;
    }
}

 



知识扩展

1.如果采用传统jpa方式,@EnableJpaRepositories无需配置,配置了也无影响。实现方式如下:

ds1相关DaoImpl
@PersistenceContext
private EntityManager entityManager;

ds2相关DaoImpl
@PersistenceContext(unitName = "secondDs")
private EntityManager entityManager;

因为ds1的entityManger声明了@Primary,所以无需指明unitName,ds2必须指明。注入了准确的entityManager,就可以直接拿来操作数据库了。service层和上面一样的,@Transactional("xxxManager")指明事物管理器即可!


2.采用jdbcTemplate方式,直接注入到Service层对象即可,so easy!
@Autowired
private JdbcTemplate jdbcTemplate;

@Autowired
private TransactionTemplate transactionTemplate;

@Resource(name="jdbcTemplate2")
private JdbcTemplate jdbcTemplate2;

@Resource(name="transactionTemplate2")
private TransactionTemplate transactionTemplate2;


好了,spring boot 多数据源,完美解决! 而且三种数据库操作方法均支持,包括事物。已经经过实践证明了! 这是官方给出的最佳实践,知识官方文档没写细。导致整整坑了我几天。至此,spring boot框架的使用就告一段落了!





六、spring boot 配置多数据源