详解Spring多数据源如何切换

public class DynamicDataSource extends AbstractRoutingDataSource {  
  
    @Override  
    protected Object determineCurrentLookupKey() {  
        // 这里可以根据需要返回不同的数据源标识符  
        // 例如，从ThreadLocal中获取当前线程的数据源标识符  
        return DataSourceContextHolder.getCurrentDataSource();  
    }  
}  
  
// 用于保存当前线程的数据源标识符的工具类  
public class DataSourceContextHolder {  
  
    private static final ThreadLocal<String> contextHolder = new ThreadLocal<>();  
  
    public static void setCurrentDataSource(String dataSource) {  
        contextHolder.set(dataSource);  
    }  
  
    public static String getCurrentDataSource() {  
        return contextHolder.get();  
    }  
  
    public static void clearCurrentDataSource() {  
        contextHolder.remove();  
    }  
}

@Configuration  
public class DataSourceConfig {  
  
    @Bean(name = "primaryDataSource")  
    @ConfigurationProperties(prefix = "spring.datasource.primary")  
    public DataSource primaryDataSource() {  
        // ... 配置并返回DataSource 
        return DataSourceBuilder.create().build(); 
    }  
  
    @Bean(name = "secondaryDataSource")  
    @ConfigurationProperties(prefix = "spring.datasource.secondary")  
    public DataSource secondaryDataSource() {  
        // ... 配置并返回DataSource  
        return DataSourceBuilder.create().build();
    }  
  
    @Bean(name = "dataSource")  
    public DataSource dynamicDataSource() {  
        DynamicDataSource dataSource = new DynamicDataSource();  
        Map<Object, Object> targetDataSources = new HashMap<>();  
        targetDataSources.put("primary", primaryDataSource());  
        targetDataSources.put("secondary", secondaryDataSource());  
        dataSource.setTargetDataSources(targetDataSources);  
        dataSource.setDefaultTargetDataSource(primaryDataSource());  
        return dataSource;  
    }  
  
    // 配置其他必要的组件，如EntityManagerFactory和TransactionManager（如果需要）  
}

@Aspect  
@Component  
public class DataSourceAspect {  
  
    @Pointcut("@annotation(customDataSource)")  
    public void dataSourcePointcut(CustomDataSource customDataSource) {}  
  
    @Before("dataSourcePointcut(customDataSource)")  
    public void switchDataSource(JoinPoint joinPoint, CustomDataSource customDataSource) {  
        DataSourceContextHolder.setCurrentDataSource(customDataSource.value());  
    }  
  
    @After("@annotation(customDataSource)")  
    public void restoreDataSource(JoinPoint joinPoint, CustomDataSource customDataSource) {  
        DataSourceContextHolder.clearCurrentDataSource();  
    }  
}  
  
// 自定义注解，用于指定数据源  
@Target({ElementType.METHOD, ElementType.TYPE})  
@Retention(RetentionPolicy.RUNTIME)  
public @interface CustomDataSource {  
  
    String value() default "primary";  
}