Spring Boot集成Mybatis双数据源

这里用到了Spring Boot + Mybatis + DynamicDataSource配置动态双数据源，可以动态切换数据源实现数据库的读写分离。

添加依赖

加入Mybatis启动器，这里添加了Druid连接池、Oracle数据库驱动为例。

<dependency>    <groupId>org.mybatis.spring.boot</groupId>    <artifactId>mybatis-spring-boot-starter</artifactId></dependency><dependency>    <groupId>com.alibaba</groupId>    <artifactId>druid</artifactId></dependency><dependency>    <groupId>com.oracle</groupId>    <artifactId>ojdbc6</artifactId></dependency>

添加启动类

@EnableMybatis@EnableTransactionManagement@SpringBootApplication(exclude = { DataSourceAutoConfiguration.class })public class Application {    public static void main(String[] args) {        SpringApplication.run(ServiceApplication.class, args);    }}

@SpringBootApplication(exclude = { DataSourceAutoConfiguration.class })：
这里用到了双数据源，需要排除数据源的自动配置，如果只有一个数据源用Spring Boot的自动配置就行。

@EnableTransactionManagement：开启事务支持。

@EnableMybatis：开启Mybatis功能

@Target(ElementType.TYPE)@Retention(RetentionPolicy.RUNTIME)@Documented@Import(MybatisConfig.class)public @interface EnableMybatis {}

Mybatis配置类

@Configuration@MapperScan(basePackages = DSConfig.BASE_PACKAGES)public class MybatisConfig implements DSConfig {    @Primary    @Bean    public DynamicDataSource dynamicDataSource(@Qualifier(DB_MASTER) DataSource master,            @Qualifier(DB_SLAVE) DataSource slave) {        Map<Object, Object> dsMap = new HashMap<>();        dsMap.put(DB_MASTER, master);        dsMap.put(DB_MASTER, slave);        DynamicDataSource dynamicDataSource = new DynamicDataSource();        dynamicDataSource.setDefaultTargetDataSource(master);        dynamicDataSource.setTargetDataSources(dsMap);        return dynamicDataSource;    }    @Bean    public PlatformTransactionManager transactionManager(DynamicDataSource dynamicDataSource) {        return new DataSourceTransactionManager(dynamicDataSource);    }    @Bean    public SqlSessionFactory sqlSessionFactory(DynamicDataSource dynamicDataSource)            throws Exception {        SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean();        sessionFactory.setDataSource(dynamicDataSource);        sessionFactory.setMapperLocations(                ((ResourcePatternResolver) new PathMatchingResourcePatternResolver())                        .getResources(DSConfig.MAPPER_LOCATIONS));        return sessionFactory.getObject();    }}

DSConfig常量类：

public interface DSConfig {    String DS_PREFIX = "spring.datasource";    String DS_ACTIVE = "active";    String DB_MASTER = "db-master";    String DB_SLAVE = "db-slave";    String DRUID = "druid";    String DRUID_MONITOR_USERNAME = "spring.druid.username";    String DRUID_MONITOR_PASSWORD = "spring.druid.password";    String DRUID_MONITOR_URL = "/druid/*";    String DRUID_FILTER_EXCLUSIONS = "*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*";    String DRUID_FILTER_URL = "/*";    String BASE_PACKAGES = "com.example.**.mapper";    String MAPPER_LOCATIONS = "mapper/**/*.xml";}

连接池配置类

Druid连接池的自动配置类：

@Configuration@Import({ PropertiesConfig.class })@ConditionalOnClass(DruidDataSource.class)@ConditionalOnProperty(prefix = DSConfig.DS_PREFIX, value = DSConfig.DS_ACTIVE, havingValue = DSConfig.DRUID)public class DruidAutoConfig implements DSConfig {    private Logger logger = LoggerUtils.getLogger(this);    @Bean(name = DB_MASTER, initMethod = "init", destroyMethod = "close")    public DataSource dataSourceMaster(DruidMasterProperties masterProperties) throws SQLException {        logger.debug("master properties: {}", masterProperties.toString());        DruidDataSource dds = new DruidDataSource();        dds.setDriverClassName(masterProperties.getDriverClassName());        dds.setUrl(masterProperties.getUrl());        dds.setUsername(masterProperties.getUsername());        dds.setPassword(masterProperties.getPassword());        dds.setInitialSize(masterProperties.getInitialSize());        dds.setMinIdle(masterProperties.getMinIdle());        dds.setMaxActive(masterProperties.getMaxActive());        dds.setMaxWait(masterProperties.getMaxWait());        dds.setTimeBetweenEvictionRunsMillis(masterProperties.getTimeBetweenEvictionRunsMillis());        dds.setMinEvictableIdleTimeMillis(masterProperties.getMinEvictableIdleTimeMillis());        dds.setValidationQuery(masterProperties.getValidationQuery());        dds.setTestOnBorrow(masterProperties.isTestOnBorrow());        dds.setTestWhileIdle(masterProperties.isTestWhileIdle());        dds.setTestOnReturn(masterProperties.isTestOnReturn());        dds.setPoolPreparedStatements(masterProperties.isPoolPreparedStatements());        dds.setMaxPoolPreparedStatementPerConnectionSize(                masterProperties.getMaxPoolPreparedStatementPerConnectionSize());        dds.setFilters(masterProperties.getFilters());        return dds;    }    @Bean(name = DB_SLAVE, initMethod = "init", destroyMethod = "close")    public DataSource dataSourceSlave(DruidSlaveProperties slaveProperties) throws SQLException {        logger.debug("slave properties: {}", slaveProperties.toString());        DruidDataSource dds = new DruidDataSource();        dds.setDriverClassName(slaveProperties.getDriverClassName());        dds.setUrl(slaveProperties.getUrl());        dds.setUsername(slaveProperties.getUsername());        dds.setPassword(slaveProperties.getPassword());        dds.setInitialSize(slaveProperties.getInitialSize());        dds.setMinIdle(slaveProperties.getMinIdle());        dds.setMaxActive(slaveProperties.getMaxActive());        dds.setMaxWait(slaveProperties.getMaxWait());        dds.setTimeBetweenEvictionRunsMillis(slaveProperties.getTimeBetweenEvictionRunsMillis());        dds.setMinEvictableIdleTimeMillis(slaveProperties.getMinEvictableIdleTimeMillis());        dds.setValidationQuery(slaveProperties.getValidationQuery());        dds.setTestOnBorrow(slaveProperties.isTestOnBorrow());        dds.setTestWhileIdle(slaveProperties.isTestWhileIdle());        dds.setTestOnReturn(slaveProperties.isTestOnReturn());        dds.setPoolPreparedStatements(slaveProperties.isPoolPreparedStatements());        dds.setMaxPoolPreparedStatementPerConnectionSize(                slaveProperties.getMaxPoolPreparedStatementPerConnectionSize());        dds.setFilters(slaveProperties.getFilters());        return dds;    }    @Bean    public ServletRegistrationBean druidServletRegistrationBean(EnvConfig env) {        String username = env.getStringValue(DSConfig.DRUID_MONITOR_USERNAME);        String password = env.getStringValue(DSConfig.DRUID_MONITOR_PASSWORD);        return new ServletRegistrationBean(new DruidStatViewServlet(username, password),                DSConfig.DRUID_MONITOR_URL);    }    @Bean    public FilterRegistrationBean druidFilterRegistrationBean() {        WebStatFilter wsf = new WebStatFilter();        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();        filterRegistrationBean.setFilter(wsf);        filterRegistrationBean.setUrlPatterns(Arrays.asList(DSConfig.DRUID_FILTER_URL));        filterRegistrationBean.setInitParameters(                Collections.singletonMap("exclusions", DSConfig.DRUID_FILTER_EXCLUSIONS));        return filterRegistrationBean;    }}

根据类路径下有DruidDataSource这个类即有Druid这个jar包和配置文件中spring.datasource.active=druid才开启对Druid连接池的自动配置。

导入的配置文件：

@Configuration@ComponentScan(basePackages = "com.example.common.config.properties")public class PropertiesConfig {}

DruidMasterProperties、DruidSlaveProperties属性文件读取的配置省略。

连接池监控配置类：

public class DruidStatViewServlet extends StatViewServlet {    private static final long serialVersionUID = 1L;    private String username;    private String password;    @Override    public String getInitParameter(String name) {        if ("loginUsername".equals(name)) {            return username;        }        if ("loginPassword".equals(name)) {            return password;        }        return super.getInitParameter(name);    }    public DruidStatViewServlet(String username, String password) {        super();        this.username = username;        this.password = password;    }    public String getUsername() {        return username;    }    public String getPassword() {        return password;    }}

在META-INF/spring.factories中加入Druid自动配置映射：

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\com.example.common.config.ds.DruidAutoConfig

切换数据源

切换数据源注解：

@Target(ElementType.METHOD)@Retention(RetentionPolicy.RUNTIME)@Documentedpublic @interface DS {    String value() default DSConfig.DB_MASTER;}

动态数据源类：

public class DynamicDataSource extends AbstractRoutingDataSource {    private final Logger logger = LoggerUtils.getLogger(this);    @Override    protected Object determineCurrentLookupKey() {        logger.debug("当前数据源为{}", DataSourceContextHolder.getDS());        return DataSourceContextHolder.getDS();    }}

动态数据源AOP实现类：

@Aspect@Componentpublic class DynamicDataSourceAspect {    @Before("@annotation(DS)")    public void beforeSwitchDS(JoinPoint point) {        Class<?> className = point.getTarget().getClass();        String methodName = point.getSignature().getName();        Class<?>[] argClass = ((MethodSignature) point.getSignature()).getParameterTypes();        String dataSource = DataSourceContextHolder.DEFAULT_DS;        try {            Method method = className.getMethod(methodName, argClass);            if (method.isAnnotationPresent(DS.class)) {                DS annotation = method.getAnnotation(DS.class);                dataSource = annotation.value();            }        } catch (Exception e) {            e.printStackTrace();        }        DataSourceContextHolder.setDS(dataSource);    }    @After("@annotation(DS)")    public void afterSwitchDS(JoinPoint point) {        DataSourceContextHolder.clearDS();    }}

绑定当前线程数据源类：

public class DataSourceContextHolder {    public static final String DEFAULT_DS = DSConfig.DB_MASTER;    private static final ThreadLocal<String> DS_HOLDER = new ThreadLocal<>();    public static void setDS(String dbType) {        DS_HOLDER.set(dbType);    }    public static String getDS() {        return (DS_HOLDER.get());    }    public static void clearDS() {        DS_HOLDER.remove();    }}

推荐阅读

---

分享一套高级视频教程：Dubbo+Zookeeper+ActiveMQ+Redis系列

分享一套分布式架构设计高级视频教程

分享一套Hadoop全套视频教程系列

去BAT面试完的Mysql面试题总结（55道，带完整答案）

阿里高级Java面试题（首发，70道，带详细答案）

2017派卧底去阿里、京东、美团、滴滴带回来的面试题及答案

Spring面试题（70道，史上最全）

通往大神之路，百度Java面试题前200页。

分享Java干货，高并发编程，热门技术教程，微服务及分布式技术，架构设计，区块链技术，人工智能，大数据，Java面试题，以及前沿热门资讯等。