需求背景

由于最近公司新项目需求，可能会用到多数据源，所以我开始研究来一下，项目是基于SpringBoot2搭建的，springboot2默认使用HikariCP作为数据库连接池,这一点需要注意，为啥使用这个，请查看这个链接http://ju.outofmemory.cn/entry/353647来了解HikariCP连接池的性能，废话不多说，上代码。

代码实现

• 数据源配置属性

hikari.master.jdbc-url=jdbc:mysql://localhost:3306/bus_data?serverTimezone=UTC&useSSL=true
hikari.master.username=root
hikari.master.password=123456
hikari.master.maximum-pool-size=20
hikari.master.pool-name=master
hikari.master.connection-timeout=30000
hikari.master.idle-timeout=600000
hikari.master.max-lifetime=1765000

hikari.slave.jdbc-url=jdbc:mysql://localhost:3306/bus_data_read?serverTimezone=UTC&useSSL=true
hikari.slave.username=root
hikari.slave.password=123456
hikari.slave.maximum-pool-size=80
hikari.slave.pool-name=slave
hikari.slave.connection-timeout=30000
hikari.slave.idle-timeout=600000
hikari.slave.max-lifetime=1765000
hikari.slave.read-only=true

• 注入配置

/**
 * TODO
 *
 * @author zhaoqing
 * @Description
 * @createTime 2018/7/13 23:57
 */
@Component
@ConfigurationProperties(prefix = "hikari")
public class DBProperties {
    private HikariDataSource master;
    private HikariDataSource slave;

    public HikariDataSource getMaster() {
        return master;
    }

    public void setMaster(HikariDataSource master) {
        this.master = master;
    }

    public HikariDataSource getSlave() {
        return slave;
    }

    public void setSlave(HikariDataSource slave) {
        this.slave = slave;
    }
}

• 动态切换数据源

@Slf4j
@Data
public class DataSourceContextHolder {

    /**
     * 默认数据源
     */
    static final String DEFAULT_DS = "dataSourceFirst";

    private static final ThreadLocal<String> contextHolder = new ThreadLocal<>();

    // 设置数据源名
    static void setDB(String dbType) {
        log.debug("切换到{}数据源", dbType);
        contextHolder.set(dbType);
    }

    // 获取数据源名
    static String getDB() {
        return contextHolder.get();
    }

    // 清除数据源名
    static void clearDB() {
        contextHolder.remove();
    }
}

• 创建动态数据源

@Configuration
public class DataSourceConfig {

    @Autowired
    private DBProperties properties;

    @Bean(name = "dynamicSource")
    public DynamicDataSource dataSource() {
        DynamicDataSource dynamicDataSource = new DynamicDataSource();

        // 添加数据源
        Map<Object, Object> dsMap = new HashMap<>(5);
        dsMap.put("dataSourceFirst", properties.getMaster());
        dsMap.put("dataSourceSecond", properties.getSlave());
        dynamicDataSource.setTargetDataSources(dsMap);
        return dynamicDataSource;
    }
}

• 定义注解

@Target({ ElementType.METHOD, ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
public @interface DBSource {
    String value() default "dataSourceFirst";
}

• 用AOP实现切换数据源逻辑

@Aspect
@Component
public class DynamicDataSourceAspect {

    @Before("@annotation(com.zqrock.productservice.config.DBSource)")
    public void beforeSwitchDS(JoinPoint point){

        //获得当前访问的class
        Class<?> className = point.getTarget().getClass();

        //获得访问的方法名
        String methodName = point.getSignature().getName();
        //得到方法的参数的类型
        Class[] argClass = ((MethodSignature)point.getSignature()).getParameterTypes();
        String dataSource = DataSourceContextHolder.DEFAULT_DS;
        try {
            // 得到访问的方法对象
            Method method = className.getMethod(methodName, argClass);

            // 判断是否存在@DS注解
            if (method.isAnnotationPresent(DBSource.class)) {
                DBSource annotation = method.getAnnotation(DBSource.class);
                // 取出注解中的数据源名
                dataSource = annotation.value();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        // 切换数据源
        DataSourceContextHolder.setDB(dataSource);
    }
    
    @After("@annotation(com.zqrock.productservice.config.DBSource)")
    public void afterSwitchDS(JoinPoint point){
        DataSourceContextHolder.clearDB();
    }
}

• DAO配置

import com.zqrock.productservice.config.DBSource;
import com.zqrock.productservice.dao.mapper.UserMapper;
import com.zqrock.productservice.model.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;

import java.util.List;

/**
 *
 *
 * @author zhaoqing
 * @Description
 * @createTime 2018/7/13 21:50
 */
@Repository
public class UserDao {
    private final UserMapper userMapper;

    @Autowired(required = false)
    public UserDao(UserMapper userMapper) {
        this.userMapper = userMapper;
    }

    @DBSource("dataSourceFirst")
    public List<User> getAllUsers(){
        return userMapper.getAllUsers();
    }

    @DBSource("dataSourceSecond")
    public User getUserById(int id){
        return userMapper.getUserById(id);
    }
}

至此,全部核心代码已都贴出,有问题请及时留言,欢迎一起交流!