【DB系列】Mybatis基于AbstractRoutingDataSource与AOP实现多数据源切换

// 返回选中的数据源
protected DataSource determineTargetDataSource() {
    Assert.notNull(this.resolvedDataSources, "DataSource router not initialized");
    Object lookupKey = this.determineCurrentLookupKey();
    DataSource dataSource = (DataSource)this.resolvedDataSources.get(lookupKey);
    if (dataSource == null && (this.lenientFallback || lookupKey == null)) {
        dataSource = this.resolvedDefaultDataSource;
    }

    if (dataSource == null) {
        throw new IllegalStateException("Cannot determine target DataSource for lookup key [" + lookupKey + "]");
    } else {
        return dataSource;
    }
}

@Nullable
protected abstract Object determineCurrentLookupKey();

public class DynamicDataSource extends AbstractRoutingDataSource {
    @Override
    protected Object determineCurrentLookupKey() {
        String dataBaseType = DSTypeContainer.getDataBaseType();
        return dataBaseType;
    }
}

public class DSTypeContainer {
    private static final ThreadLocal<String> TYPE = new ThreadLocal<String>();

    public static String defaultType;

    /**
     * 往当前线程里设置数据源类型
     *
     * @param dataBase
     */
    public static void setDataBaseType(String dataBase) {
        if (StringUtils.isEmpty(dataBase)) {
            dataBase = defaultType;
        }
        TYPE.set(dataBase);
        System.err.println("[将当前数据源改为]：" + dataBase);
    }

    /**
     * 获取数据源类型
     *
     * @return
     */
    public static String getDataBaseType() {
        String database = TYPE.get();
        System.err.println("[获取当前数据源的类型为]：" + database);
        return database;
    }

    /**
     * 清空数据类型
     */
    public static void clearDataBaseType() {
        TYPE.remove();
    }
}

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Inherited
public @interface DS {
    String value() default "";
}

@Aspect
@Component
public class DsAspect {

    // 拦截类上有DS注解的方法调用
    @Around("@within(DS)")
    public Object dsAround(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {
        DS ds = (DS) proceedingJoinPoint.getSignature().getDeclaringType().getAnnotation(DS.class);
        try {
            // 写入线程上下文，应该用哪个DB
            DSTypeContainer.setDataBaseType(ds == null ? null : ds.value());
            return proceedingJoinPoint.proceed();
        } finally {
            // 清空上下文信息
            DSTypeContainer.clearDataBaseType();
        }
    }
}

@Data
@ConfigurationProperties(prefix = "spring.dynamic")
public class DSProperties {
    private Map<String, DataSourceProperties> datasource;
}

@Configuration
@EnableConfigurationProperties(DSProperties.class)
@MapperScan(basePackages = {"com.git.hui.boot.multi.datasource.mapper"},
        sqlSessionFactoryRef = "SqlSessionFactory")
public class DynamicDataSourceConfig {

    @SuppressWarnings("unchecked")
    @Bean(name = "dynamicDataSource")
    public DynamicDataSource DataSource(DSProperties dsProperties) {
        Map targetDataSource = new HashMap<>(8);
        dsProperties.getDatasource().forEach((k, v) -> {
            targetDataSource.put(k, v.initializeDataSourceBuilder().build());
        });
        DynamicDataSource dataSource = new DynamicDataSource();
        dataSource.setTargetDataSources(targetDataSource);

        // 设置默认的数据库，下面这个赋值方式写法不太推荐，这里只是为了方便而已
        DSTypeContainer.defaultType = (String) targetDataSource.keySet().stream().findFirst().get();
        dataSource.setDefaultTargetDataSource(targetDataSource.get(DSTypeContainer.defaultType));
        return dataSource;
    }

    @Bean(name = "SqlSessionFactory")
    public SqlSessionFactory test1SqlSessionFactory(@Qualifier("dynamicDataSource") DataSource dynamicDataSource)
            throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dynamicDataSource);
        bean.setMapperLocations(
                new PathMatchingResourcePatternResolver().getResources("classpath*:mapping/*/*.xml"));
        return bean.getObject();
    }
}

@Data
public class StoryMoneyEntity {
    private Integer id;

    private String name;

    private Long money;

    private Integer isDeleted;

    private Timestamp createAt;

    private Timestamp updateAt;
}

@DS(value = "story")
@Mapper
public interface StoryMoneyMapper {
    List<StoryMoneyEntity> findByIds(List<Integer> ids);
}

@DS(value = "test")
@Mapper
public interface TestMoneyMapper {
    List<TestMoneyEntity> findByIds(List<Integer> ids);
}

@Repository
public class StoryMoneyRepository {
    @Autowired
    private StoryMoneyMapper storyMoneyMapper;

    public void query() {
        List<StoryMoneyEntity> list = storyMoneyMapper.findByIds(Arrays.asList(1, 1000));
        System.out.println(list);
    }
}

@Repository
public class TestMoneyRepository {
    @Autowired
    private TestMoneyMapper testMoneyMapper;

    public void query() {
        List<TestMoneyEntity> list = testMoneyMapper.findByIds(Arrays.asList(1, 1000));
        System.out.println(list);
    }
}

@SpringBootApplication
public class Application {

    public Application(StoryMoneyRepository storyMoneyRepository, TestMoneyRepository testMoneyRepository) {
        storyMoneyRepository.query();
        testMoneyRepository.query();
    }

    public static void main(String[] args) {
        SpringApplication.run(Application.class);
    }
}