spring3.0 多数据源的实现（跨数据库）

先上xml配置 ps:实际上你可以选择java注解的方式

    <bean name="dataSource" class="com.alibaba.druid.pool.DruidDataSource"
          init-method="init" destroy-method="close">
        <property name="driverClassName" value="${jdbc.driverClassName}" />
        <property name="url" value="${jdbc.url}" />
        <property name="username" value="${jdbc.username}" />
        <property name="password" value="${jdbc.password}" />
     
    </bean>

    <bean name="dataSource2" class="com.alibaba.druid.pool.DruidDataSource"
          init-method="init" destroy-method="close">
        <property name="driverClassName" value="com.mysql.jdbc.Driver" />
        <property name="url" value="jdbc:mysql://127.0.0.1:39000/apptest?useUnicode=true" />
        <property name="username" value="root" />
        <property name="password" value="root" />
    </bean>

<!-- 动态数据源配置，这个class要实现 -->
    <bean id="dynamicDataSource" 
                  class="com.data.util.jdbcutil.DynamicDataSource">
        <property name="targetDataSources">
            <map key-type="java.lang.String">
                <!-- 指定lookupKey和与之对应的数据源,切换时使用的为key -->
                <entry key="dataSource1" value-ref="dataSource"></entry>
                <entry key="dataSource2" value-ref="dataSource2"></entry>
            </map>
        </property>
        <!-- 这里可以指定默认的数据源 -->
        <property name="defaultTargetDataSource" ref="dataSource" />
    </bean>

<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dynamicDataSource" />
        <!-- 自动扫描mapping.xml文件 -->
        <property name="mapperLocations" value="classpath:com/*/mapping/**/*.xml">
        </property>
        <property name="configLocation" value="classpath:mybatis-config.xml">
        </property>
</bean>
    <bean id="dataSourceAspect" class="com.data.util.jdbcutil.DataSourceAspect" />
    <aop:config>
        <aop:aspect ref="dataSourceAspect">
<!--            拦截所有service方法,切面插入拦截的方法，获取注解-->
            <aop:pointcut id="dataSourcePointcut" expression="@annotation(com.data.util.jdbcutil.DataSource)" />
            <aop:around pointcut-ref="dataSourcePointcut" method="intercept" />
        </aop:aspect>
    </aop:config>

image.png

如图所示四个类实现了切换数据源

DataSource ---注解，实现标记功能
DataSourceAspect ---实现切换数据源功能
DynamicDataSource --- 实现AbstractRoutingDataSource的模板方法
DynamicDataSourceHolder --- 使用线程储存数据源的key

@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface DataSource {
    String value();
}

public class DataSourceAspect {
    /**
     * 拦截目标方法，获取由@DataSource指定的数据源标识，设置到线程存储中以便切换数据源
     *
     * @param point
     * @throws Exception
     */
    public Object intercept(ProceedingJoinPoint point)  {
        try{
            Class<?> target = point.getTarget().getClass();
            MethodSignature signature = (MethodSignature) point.getSignature();
            // 默认使用目标类型的注解，如果没有则使用其实现接口的注解
            for (Class<?> clazz : target.getInterfaces()) {
                resolveDataSource(clazz, signature.getMethod());
            }
            resolveDataSource(target, signature.getMethod());
            return point.proceed();
        } catch (Throwable throwable) {
            throwable.printStackTrace();
        } finally {
            DynamicDataSourceHolder.clearDataSource();
        }
        return null;
    }

    /**
     * 提取目标对象方法注解和类型注解中的数据源标识
     *
     * @param clazz
     * @param method
     */
    private void resolveDataSource(Class<?> clazz, Method method) {
        try {
            Class<?>[] types = method.getParameterTypes();
            // 默认使用类型注解
            if (clazz.isAnnotationPresent(DataSource.class)) {
                DataSource source = clazz.getAnnotation(DataSource.class);
                DynamicDataSourceHolder.setDataSource(source.value());
            }
            // 方法注解可以覆盖类型注解
            Method m = clazz.getMethod(method.getName(), types);
            if (m != null && m.isAnnotationPresent(DataSource.class)) {
                DataSource source = m.getAnnotation(DataSource.class);
                DynamicDataSourceHolder.setDataSource(source.value());
            }
        } catch (Exception e) {
        }
    }
}

public class DynamicDataSource extends AbstractRoutingDataSource {
    @Override
    protected Object determineCurrentLookupKey() {
        return DynamicDataSourceHolder.getDataSource();
    }
}

public class DynamicDataSourceHolder {
    /**
     * 注意：数据源标识保存在线程变量中，避免多线程操作数据源时互相干扰
     */
    private static final ThreadLocal<String> THREAD_DATA_SOURCE = new ThreadLocal<String>();

    public static String getDataSource() {
        return THREAD_DATA_SOURCE.get();
    }

    public static void setDataSource(String dataSource) {
        THREAD_DATA_SOURCE.set(dataSource);
    }

    public static void clearDataSource() {
        THREAD_DATA_SOURCE.remove();
    }
}

使用案例

    @Autowired
    private MXGLMapper mapper;
    @DataSource("dataSource2")
    public List<Map<String,Object>>  getmodel_table_prvd(){
     return mapper.getList();
    }
    @DataSource("dataSource")
    public List<Map<String, Object>> getmodel_table_prvd1() {
        return mapper.getList();
    }