关于
有时候，随着业务的发展，项目关联的数据来源会变得越来越复杂，使用的数据库会比较分散，这个时候就会采用多数据源的方式来获取数据。另外，多数据源也有其他好处，例如分布式数据库的读写分离，集成多种数据库等等。下面分享我在实际项目中配置多数据源的案例。
步骤
1.application.yml文件中，配置数据库源。这里primary是主库，secondary是从库。
server:
port: 8089
# 多数据源配置
#primary
spring:
primary:
datasource:
url: jdbc:mysql://127.0.0.1:3306/database1?autoReconnect=true&useUnicode=true&characterEncoding=UTF-8&useSSL=false&useLegacyDatetimeCode=false&serverTimezone=Asia/Shanghai
username: root
password: ******
driver-class-name: com.mysql.jdbc.Driver
#secondary
secondary:
datasource:
url: jdbc:mysql://127.0.0.1:3306/database1?autoReconnect=true&useUnicode=true&characterEncoding=UTF-8&useSSL=false&useLegacyDatetimeCode=false&serverTimezone=Asia/Shanghai
username: root
password: ******
driver-class-name: com.mysql.jdbc.Driver
jpa:
hibernate:
primary-dialect: org.hibernate.dialect.MySQL5Dialect
secondary-dialect: org.hibernate.dialect.MySQL5Dialect
open-in-view: true
show-sql: true
2.创建一个Spring配置类，其中spring.primary.datasource的路径参考yml文件的配置。
@Configuration
public class DataSourceConfig {
@Bean(name = "primaryDataSource")
@Qualifier("primaryDataSource")
@ConfigurationProperties(prefix="spring.primary.datasource")
public DataSource primaryDataSource() {
return DataSourceBuilder.create().build();
}
@Bean(name = "secondaryDataSource")
@Qualifier("secondaryDataSource")
@Primary
@ConfigurationProperties(prefix="spring.secondary.datasource")
public DataSource secondaryDataSource() {
return DataSourceBuilder.create().build();
}
}
3.分别创建主库、从库的配置类。
注意：entity包和dao包的配置，以及@Primary注解指定主库。
主库配置类：
@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
entityManagerFactoryRef = "entityManagerFactoryPrimary",
transactionManagerRef = "transactionManagerPrimary",
basePackages = {"com.infinitus.yunxiao_data.dao.primary"}) //设置Repository所在位置
public class PrimaryConfig {
@Autowired
private JpaProperties jpaProperties;
@Autowired
@Qualifier("primaryDataSource")
private DataSource primaryDataSource;
@Primary
@Bean(name = "entityManagerPrimary")
public EntityManager entityManager(EntityManagerFactoryBuilder builder) {
return entityManagerFactoryPrimary(builder).getObject().createEntityManager();
}
@Primary
@Bean(name = "entityManagerFactoryPrimary")
public LocalContainerEntityManagerFactoryBean entityManagerFactoryPrimary(EntityManagerFactoryBuilder builder) {
return builder
.dataSource(primaryDataSource)
.properties(getVendorProperties(primaryDataSource))
.packages("com.infinitus.yunxiao_data.entity.primary") //设置实体类所在位置
.persistenceUnit("primaryPersistenceUnit")
.build();
}
private Map getVendorProperties(DataSource dataSource) {
return jpaProperties.getHibernateProperties(dataSource);
}
@Primary
@Bean(name = "transactionManagerPrimary")
public PlatformTransactionManager transactionManagerPrimary(EntityManagerFactoryBuilder builder) {
return new JpaTransactionManager(entityManagerFactoryPrimary(builder).getObject());
}
}
从库的配置类：
@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
entityManagerFactoryRef = "entityManagerFactorySecondary",
transactionManagerRef = "transactionManagerSecondary",
basePackages = {"com.infinitus.yunxiao_data.dao.secondary"}) //设置Repository所在位置
public class SecondaryConfig {
@Autowired
private JpaProperties jpaProperties;
@Autowired
@Qualifier("secondaryDataSource")
private DataSource secondaryDataSource;
@Bean(name = "entityManagerSecondary")
public EntityManager entityManager(EntityManagerFactoryBuilder builder) {
return entityManagerFactorySecondary(builder).getObject().createEntityManager();
}
@Bean(name = "entityManagerFactorySecondary")
public LocalContainerEntityManagerFactoryBean entityManagerFactorySecondary(EntityManagerFactoryBuilder builder) {
return builder
.dataSource(secondaryDataSource)
.properties(getVendorProperties(secondaryDataSource))
.packages("com.infinitus.yunxiao_data.entity.secondary") //设置实体类所在位置
.persistenceUnit("primaryPersistenceUnit")
.build();
}
private Map getVendorProperties(DataSource dataSource) {
return jpaProperties.getHibernateProperties(dataSource);
}
@Bean(name = "transactionManagerSecondary")
PlatformTransactionManager transactionManagerSecondary(EntityManagerFactoryBuilder builder) {
return new JpaTransactionManager(entityManagerFactorySecondary(builder).getObject());
}
}
4.分别创建主、从库dao类。
主dao：
@Repository
public interface PrimaryRepository extends JpaRepository<PrimaryEntity, Long> {
@Query(value = "SELECT p FROM PrimaryEntity p")
List<PrimaryEntity> queryList();
}
从dao：
@Repository
public interface SecondaryRepository extends JpaRepository<SecondaryEntity, Long> {
@Query(value = "SELECT p FROM SecondaryEntity p")
List<SecondaryEntity> queryList();
}
5.分别创建主、从库entity类。
主entity：
@Entity
@Table(name = "holiday_scheme")
@EntityListeners(AuditingEntityListener.class)
public class PrimaryEntity extends AbstractPersistable<Long> {
@Column(name = "date")
public String date;
@Column(name = "hour")
public String hour;
@Column(name = "holiday")
public String holiday;
@Column(name = "holiday_explain")
public String holiday_explain;
public String getDate() {
return date;
}
public void setDate(String date) {
this.date = date;
}
public String getHour() {
return hour;
}
public void setHour(String hour) {
this.hour = hour;
}
public String getHoliday() {
return holiday;
}
public void setHoliday(String holiday) {
this.holiday = holiday;
}
public String getHoliday_explain() {
return holiday_explain;
}
public void setHoliday_explain(String holiday_explain) {
this.holiday_explain = holiday_explain;
}
@Override
public String toString() {
return "PrimaryEntity{" +
"date='" + date + '\'' +
", hour='" + hour + '\'' +
", holiday='" + holiday + '\'' +
", holiday_explain='" + holiday_explain + '\'' +
'}';
}
}
从entity：
@Entity
@Table(name = "active_dashboards")
@EntityListeners(AuditingEntityListener.class)
public class SecondaryEntity extends AbstractPersistable<Long> {
@Column(name = "dashboard_id")
public String dashboard_id;
@Column(name = "user_id")
public String user_id;
@Column(name = "order_index")
public String order_index;
public String getDashboard_id() {
return dashboard_id;
}
public void setDashboard_id(String dashboard_id) {
this.dashboard_id = dashboard_id;
}
public String getUser_id() {
return user_id;
}
public void setUser_id(String user_id) {
this.user_id = user_id;
}
public String getOrder_index() {
return order_index;
}
public void setOrder_index(String order_index) {
this.order_index = order_index;
}
@Override
public String toString() {
return "SecondaryEntity{" +
"dashboard_id='" + dashboard_id + '\'' +
", user_id='" + user_id + '\'' +
", order_index='" + order_index + '\'' +
'}';
}
}
6.controller请求获取不同数据库的数据。
@RestController
@RequestMapping("/database")
public class MailController {
private final Logger logger = LoggerFactory.getLogger(this.getClass());
@Autowired
PrimaryRepository primaryRepository;
@Autowired
SecondaryRepository secondaryRepository;
@RequestMapping("/primary")
@ResponseBody
public String primary() {
return primaryRepository.queryList().toString();
}
@RequestMapping("/secondary")
@ResponseBody
public String secondary() {
return secondaryRepository.queryList().toString();
}
}
注意
下面提两个在配置多数据源时遇到的坑点，一不注意就掉坑了。
1.Application类不需要配置@EnableJpaRepositories注解，会报如下错误。
A component required a bean named 'entityManagerFactory' that could not be f
2.注意检查dao类，获取数据的方法上格式是否正确，有没有某个字段是表中不存在的，避免启动异常。如下，SecondaryEntity表中是不存在job_name字段的，所以注释掉才能启动成功等。
//@Query(value = "SELECT p FROM SecondaryEntity p where p.job_name = ?1")
//List<SecondaryEntity> queryOdcRecord(String job_name);
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