spring+mybatis多数据源，动态切换

有时我们项目中需要配置多个数据源，不同的业务使用的数据库不同

实现思路：
配置多个dataSource ，再配置多个sqlSessionFactory，和dataSource一一对应。
重写SqlSessionTemplate，支持多个sqlSessionFactory。最后配置mybatis自动扫描MapperScannerConfigurer。增加切面，在访问数据库前动态获取数据源

相关配置

    <!-- 配置sqlSessionFactory -->
    <bean id="sqlSessionFactory_product" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource_product" />
        <property name="configLocation" value="classpath:mybatis-config.xml" />
        <property name="mapperLocations" value="classpath*:com/zyx/demo/**/*Mapper.xml"/>
    </bean>
    <!-- 配置sqlSessionFactory -->
    <bean id="sqlSessionFactory_promotion" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource_promotion" />
        <property name="configLocation" value="classpath:mybatis-config.xml" />
        <property name="mapperLocations" value="classpath*:com/zyx/demo/**/*Mapper.xml"/>
    </bean>


    <!-- 重写sqlSessionTemplate实现，支持多个SQLSessionFactory -->
    <bean id="dynamicSqlSessionTemplate" class="com.zyx.demo.common.mybatis.DynamicSqlSessionTemplate">
        <constructor-arg name="sqlSessionFactory" ref="sqlSessionFactory_product" />
        <property name="targetSqlSessionFactorys">
            <map key-type="java.lang.String">
                <entry value-ref="sqlSessionFactory_product" key="PRODUCT" />
                <entry value-ref="sqlSessionFactory_promotion" key="PROMOTION" />
            </map>
        </property>
        <property name="defaultTargetSqlSessionFactory" ref="sqlSessionFactory_product" />
    </bean>

    <!-- 配置MapperScannerConfigurer -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="sqlSessionTemplateBeanName" value="dynamicSqlSessionTemplate" />
        <property name="basePackage" value="com.zyx.demo.**.dao" />
    </bean>

    <!-- 定义切面 -->
    <bean id="dynamicDataSourceAspectJ" class="com.zyx.demo.common.aop.DynamicDataSourceAspectJ" />
    <aop:config proxy-target-class="false" expose-proxy="true">
        <aop:pointcut expression="execution(* com.zyx.demo.*.dao..*.*(..))" id="datasource-pointcut" />
        <aop:aspect ref="dynamicDataSourceAspectJ">
            <aop:before method="switchDataSource" pointcut-ref="datasource-pointcut" />
        </aop:aspect>
    </aop:config>

重写sqlSessionTemplate

public class DynamicSqlSessionTemplate extends SqlSessionTemplate {

    private static Logger logger = LoggerFactory.getLogger(DynamicSqlSessionTemplate.class);

    private SqlSessionFactory sqlSessionFactory;
    private ExecutorType executorType;
    private SqlSession sqlSessionProxy;
    private PersistenceExceptionTranslator exceptionTranslator;
    private Map<Object, SqlSessionFactory> targetSqlSessionFactorys;
    private SqlSessionFactory defaultTargetSqlSessionFactory;

    public void setTargetSqlSessionFactorys(Map<Object, SqlSessionFactory> targetSqlSessionFactorys) {
        this.targetSqlSessionFactorys = targetSqlSessionFactorys;
    }

    public void setDefaultTargetSqlSessionFactory(SqlSessionFactory defaultTargetSqlSessionFactory) {
        this.defaultTargetSqlSessionFactory = defaultTargetSqlSessionFactory;
    }

    public DynamicSqlSessionTemplate(SqlSessionFactory sqlSessionFactory) {
        this(sqlSessionFactory, sqlSessionFactory.getConfiguration().getDefaultExecutorType());
    }

    public DynamicSqlSessionTemplate(SqlSessionFactory sqlSessionFactory, ExecutorType executorType) {
        this(sqlSessionFactory, executorType, new MyBatisExceptionTranslator(sqlSessionFactory.getConfiguration().getEnvironment().getDataSource(), true));
    }

    public DynamicSqlSessionTemplate(SqlSessionFactory sqlSessionFactory, ExecutorType executorType, PersistenceExceptionTranslator exceptionTranslator) {
        super(sqlSessionFactory, executorType, exceptionTranslator);
        this.sqlSessionFactory = sqlSessionFactory;
        this.executorType = executorType;
        this.exceptionTranslator = exceptionTranslator;
        this.sqlSessionProxy = (SqlSession) newProxyInstance(SqlSessionFactory.class.getClassLoader(), new Class[] { SqlSession.class }, new SqlSessionInterceptor());
        this.defaultTargetSqlSessionFactory = sqlSessionFactory;
    }

    @Override
    public SqlSessionFactory getSqlSessionFactory() {
        String dataSourceType = DynamicDataSourceContextHolder.getDataSourceType();
        SqlSessionFactory targetSqlSessionFactory = targetSqlSessionFactorys.get(dataSourceType);
        if (targetSqlSessionFactory != null) {
            return targetSqlSessionFactory;
        } else if (defaultTargetSqlSessionFactory != null) {
            if (dataSourceType != null) {
                logger.warn("此[" + dataSourceType + "]dataSourceType未配置文件中配置targetSqlSessionFactorys,将会返回defaultTargetSqlSessionFactory来执行后面的操作");
            }
            return defaultTargetSqlSessionFactory;
        } else {
            Assert.notNull(targetSqlSessionFactorys, "Property 'targetSqlSessionFactorys' or 'defaultTargetSqlSessionFactory' are required");
            Assert.notNull(defaultTargetSqlSessionFactory, "Property 'defaultTargetSqlSessionFactory' or 'targetSqlSessionFactorys' are required");
        }
        return this.sqlSessionFactory;
    }

    @Override
    public Configuration getConfiguration() {
        return this.getSqlSessionFactory().getConfiguration();
    }

    public ExecutorType getExecutorType() {
        return this.executorType;
    }

    public PersistenceExceptionTranslator getPersistenceExceptionTranslator() {
        return this.exceptionTranslator;
    }

    public <T> T selectOne(String statement) {
        return this.sqlSessionProxy.<T> selectOne(statement);
    }

    public <T> T selectOne(String statement, Object parameter) {
        return this.sqlSessionProxy.<T> selectOne(statement, parameter);
    }

    public <K, V> Map<K, V> selectMap(String statement, String mapKey) {
        return this.sqlSessionProxy.<K, V> selectMap(statement, mapKey);
    }

    public <K, V> Map<K, V> selectMap(String statement, Object parameter, String mapKey) {
        return this.sqlSessionProxy.<K, V> selectMap(statement, parameter, mapKey);
    }

    public <K, V> Map<K, V> selectMap(String statement, Object parameter, String mapKey, RowBounds rowBounds) {
        return this.sqlSessionProxy.<K, V> selectMap(statement, parameter, mapKey, rowBounds);
    }

    public <E> List<E> selectList(String statement) {
        return this.sqlSessionProxy.<E> selectList(statement);
    }

    public <E> List<E> selectList(String statement, Object parameter) {
        return this.sqlSessionProxy.<E> selectList(statement, parameter);
    }

    public <E> List<E> selectList(String statement, Object parameter, RowBounds rowBounds) {
        return this.sqlSessionProxy.<E> selectList(statement, parameter, rowBounds);
    }

    public void select(String statement, ResultHandler handler) {
        this.sqlSessionProxy.select(statement, handler);
    }

    public void select(String statement, Object parameter, ResultHandler handler) {
        this.sqlSessionProxy.select(statement, parameter, handler);
    }

    public void select(String statement, Object parameter, RowBounds rowBounds, ResultHandler handler) {
        this.sqlSessionProxy.select(statement, parameter, rowBounds, handler);
    }

    public int insert(String statement) {
        return this.sqlSessionProxy.insert(statement);
    }

    public int insert(String statement, Object parameter) {
        return this.sqlSessionProxy.insert(statement, parameter);
    }

    public int update(String statement) {
        return this.sqlSessionProxy.update(statement);
    }

    public int update(String statement, Object parameter) {
        return this.sqlSessionProxy.update(statement, parameter);
    }

    public int delete(String statement) {
        return this.sqlSessionProxy.delete(statement);
    }

    public int delete(String statement, Object parameter) {
        return this.sqlSessionProxy.delete(statement, parameter);
    }

    public <T> T getMapper(Class<T> type) {
        return getConfiguration().getMapper(type, this);
    }

    public void commit() {
        throw new UnsupportedOperationException("Manual commit is not allowed over a Spring managed SqlSession");
    }

    public void commit(boolean force) {
        throw new UnsupportedOperationException("Manual commit is not allowed over a Spring managed SqlSession");
    }

    public void rollback() {
        throw new UnsupportedOperationException("Manual rollback is not allowed over a Spring managed SqlSession");
    }

    public void rollback(boolean force) {
        throw new UnsupportedOperationException("Manual rollback is not allowed over a Spring managed SqlSession");
    }

    public void close() {
        throw new UnsupportedOperationException("Manual close is not allowed over a Spring managed SqlSession");
    }

    public void clearCache() {
        this.sqlSessionProxy.clearCache();
    }

    public Connection getConnection() {
        return this.sqlSessionProxy.getConnection();
    }

    public List<BatchResult> flushStatements() {
        return this.sqlSessionProxy.flushStatements();
    }

    private class SqlSessionInterceptor implements InvocationHandler {
        @Override
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
            SqlSession sqlSession = getSqlSession(DynamicSqlSessionTemplate.this.getSqlSessionFactory(), DynamicSqlSessionTemplate.this.executorType, DynamicSqlSessionTemplate.this.exceptionTranslator);
            try {
                Object result = method.invoke(sqlSession, args);
                if (!isSqlSessionTransactional(sqlSession, DynamicSqlSessionTemplate.this.getSqlSessionFactory())) {
                    sqlSession.commit(true);
                }
                return result;
            } catch (Throwable t) {
                Throwable unwrapped = unwrapThrowable(t);
                if (DynamicSqlSessionTemplate.this.exceptionTranslator != null && unwrapped instanceof PersistenceException) {
                    closeSqlSession(sqlSession, DynamicSqlSessionTemplate.this.getSqlSessionFactory());
                    sqlSession = null;
                    Throwable translated = DynamicSqlSessionTemplate.this.exceptionTranslator.translateExceptionIfPossible((PersistenceException) unwrapped);
                    if (translated != null) {
                        unwrapped = translated;
                    }
                }
                throw unwrapped;
            } finally {
                if (sqlSession != null) {
                    closeSqlSession(sqlSession, DynamicSqlSessionTemplate.this.getSqlSessionFactory());
                }
            }
        }
    }
}

增加切面

public class DynamicDataSourceAspectJ {

    private Logger logger = LoggerFactory.getLogger(DynamicDataSourceAspectJ.class);

    /**
     * 切换数据源*/
    public void switchDataSource(JoinPoint joinPoint) {
        try {
            Signature signature = joinPoint.getSignature();
            MethodSignature methodSignature = (MethodSignature) signature;
            Method method = methodSignature.getMethod();
            boolean methodAnnotation = method.isAnnotationPresent(DynamicDataSource.class);
            DynamicDataSource dynamicDataSource = method.getAnnotation(DynamicDataSource.class);
            if (!methodAnnotation) {
                Class<?> clazzs[] = joinPoint.getTarget().getClass().getInterfaces();
                if (clazzs != null && clazzs.length>0) {
                    Class<?> clazz = clazzs[0];
                    dynamicDataSource = (DynamicDataSource) clazz.getAnnotation(DynamicDataSource.class);
                    if (dynamicDataSource != null) {
                        DynamicDataSourceContextHolder.setDataSourceType(dynamicDataSource.dataSourceType());
                    }
                }
            }
        } catch (Exception e) {
            logger.error("切换数据源异常：" + e.getMessage(), e);
        }
    }
}

public class DynamicDataSourceContextHolder {

    /**
     * DataSource上下文，每个线程对应相应的数据源key
     */
    public static final ThreadLocal<String> contextHolder = new ThreadLocal<String>();
    private static Logger logger = LoggerFactory.getLogger(DynamicDataSourceContextHolder.class);
    public static void setDataSourceType(String dataSourceType) {
        contextHolder.set(dataSourceType);
    }

    public static String getDataSourceType() {String dataSourceType = contextHolder.get();
        logger.debug("当前线程Thread:" + Thread.currentThread().getName() + " 当前的数据源 key is " + dataSourceType);
        return dataSourceType;
    }

    public static void clearDataSourceType() {
        contextHolder.remove();
    }
}

自定义标签，需要在dao层的接口上声明数据源

@Target({ ElementType.METHOD, ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface DynamicDataSource {

    public final static String PRODUCT = "PRODUCT";
    public final static String PROMOTION = "PROMOTION";

    String dataSourceType() default DynamicDataSource.PRODUCT;
}