Spring Boot 集成 Mybatis 实现双数据源

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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。

1. <dependency>

2.    <groupId>org.mybatis.spring.boot</groupId>

3.    <artifactId>mybatis-spring-boot-starter</artifactId>

4. </dependency>

5. <dependency>

6.    <groupId>com.alibaba</groupId>

7.    <artifactId>druid</artifactId>

8. </dependency>

9. <dependency>

10.    <groupId>com.oracle</groupId>

11.    <artifactId>ojdbc6</artifactId>

12. </dependency>

添加启动类

1. @EnableMybatis

2. @EnableTransactionManagement

3. @SpringBootApplication(exclude = { DataSourceAutoConfiguration.class })

4. public class Application {

5.    public static void main(String[] args) {

6.        SpringApplication.run(ServiceApplication.class, args);

7.    }

8. }

@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

1. @Target(ElementType.TYPE)

2. @Retention(RetentionPolicy.RUNTIME)

3. @Documented

4. @Import(MybatisConfig.class)

5. public @interface EnableMybatis {

6. }

Mybatis配置类

1. @Configuration

2. @MapperScan(basePackages = DSConfig.BASE_PACKAGES)

3. public class MybatisConfig implements DSConfig {

4.    @Primary

5.    @Bean

6.    public DynamicDataSource dynamicDataSource(@Qualifier(DB_MASTER) DataSource master,

7.            @Qualifier(DB_SLAVE) DataSource slave) {

8.        Map<Object, Object> dsMap = new HashMap<>();

9.        dsMap.put(DB_MASTER, master);

10.        dsMap.put(DB_MASTER, slave);

11.        DynamicDataSource dynamicDataSource = new DynamicDataSource();

12.        dynamicDataSource.setDefaultTargetDataSource(master);

13.        dynamicDataSource.setTargetDataSources(dsMap);

14.        return dynamicDataSource;

15.    }

16.    @Bean

17.    public PlatformTransactionManager transactionManager(DynamicDataSource dynamicDataSource) {

18.        return new DataSourceTransactionManager(dynamicDataSource);

19.    }

20.    @Bean

21.    public SqlSessionFactory sqlSessionFactory(DynamicDataSource dynamicDataSource)

22.            throws Exception {

23.        SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean();

24.        sessionFactory.setDataSource(dynamicDataSource);

25.        sessionFactory.setMapperLocations(

26.                ((ResourcePatternResolver) new PathMatchingResourcePatternResolver())

27.                        .getResources(DSConfig.MAPPER_LOCATIONS));

28.        return sessionFactory.getObject();

29.    }

30. }

DSConfig常量类：

1. public interface DSConfig {

2.    String DS_PREFIX = "spring.datasource";

3.    String DS_ACTIVE = "active";

4.    String DB_MASTER = "db-master";

5.    String DB_SLAVE = "db-slave";

6.    String DRUID = "druid";

7.    String DRUID_MONITOR_USERNAME = "spring.druid.username";

8.    String DRUID_MONITOR_PASSWORD = "spring.druid.password";

9.    String DRUID_MONITOR_URL = "/druid/*";

10.    String DRUID_FILTER_EXCLUSIONS = "*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*";

11.    String DRUID_FILTER_URL = "/*";

12.    String BASE_PACKAGES = "com.example.**.mapper";

13.    String MAPPER_LOCATIONS = "mapper/**/*.xml";

14. }

连接池配置类

Druid连接池的自动配置类：

1. @Configuration

2. @Import({ PropertiesConfig.class })

3. @ConditionalOnClass(DruidDataSource.class)

4. @ConditionalOnProperty(prefix = DSConfig.DS_PREFIX, value = DSConfig.DS_ACTIVE, havingValue = DSConfig.DRUID)

5. public class DruidAutoConfig implements DSConfig {

6.    private Logger logger = LoggerUtils.getLogger(this);

7.    @Bean(name = DB_MASTER, initMethod = "init", destroyMethod = "close")

8.    public DataSource dataSourceMaster(DruidMasterProperties masterProperties) throws SQLException {

9.        logger.debug("master properties: {}", masterProperties.toString());

10.        DruidDataSource dds = new DruidDataSource();

11.        dds.setDriverClassName(masterProperties.getDriverClassName());

12.        dds.setUrl(masterProperties.getUrl());

13.        dds.setUsername(masterProperties.getUsername());

14.        dds.setPassword(masterProperties.getPassword());

15.        dds.setInitialSize(masterProperties.getInitialSize());

16.        dds.setMinIdle(masterProperties.getMinIdle());

17.        dds.setMaxActive(masterProperties.getMaxActive());

18.        dds.setMaxWait(masterProperties.getMaxWait());

19.        dds.setTimeBetweenEvictionRunsMillis(masterProperties.getTimeBetweenEvictionRunsMillis());

20.        dds.setMinEvictableIdleTimeMillis(masterProperties.getMinEvictableIdleTimeMillis());

21.        dds.setValidationQuery(masterProperties.getValidationQuery());

22.        dds.setTestOnBorrow(masterProperties.isTestOnBorrow());

23.        dds.setTestWhileIdle(masterProperties.isTestWhileIdle());

24.        dds.setTestOnReturn(masterProperties.isTestOnReturn());

25.        dds.setPoolPreparedStatements(masterProperties.isPoolPreparedStatements());

26.        dds.setMaxPoolPreparedStatementPerConnectionSize(

27.                masterProperties.getMaxPoolPreparedStatementPerConnectionSize());

28.        dds.setFilters(masterProperties.getFilters());

29.        return dds;

30.    }

31.    @Bean(name = DB_SLAVE, initMethod = "init", destroyMethod = "close")

32.    public DataSource dataSourceSlave(DruidSlaveProperties slaveProperties) throws SQLException {

33.        logger.debug("slave properties: {}", slaveProperties.toString());

34.        DruidDataSource dds = new DruidDataSource();

35.        dds.setDriverClassName(slaveProperties.getDriverClassName());

36.        dds.setUrl(slaveProperties.getUrl());

37.        dds.setUsername(slaveProperties.getUsername());

38.        dds.setPassword(slaveProperties.getPassword());

39.        dds.setInitialSize(slaveProperties.getInitialSize());

40.        dds.setMinIdle(slaveProperties.getMinIdle());

41.        dds.setMaxActive(slaveProperties.getMaxActive());

42.        dds.setMaxWait(slaveProperties.getMaxWait());

43.        dds.setTimeBetweenEvictionRunsMillis(slaveProperties.getTimeBetweenEvictionRunsMillis());

44.        dds.setMinEvictableIdleTimeMillis(slaveProperties.getMinEvictableIdleTimeMillis());

45.        dds.setValidationQuery(slaveProperties.getValidationQuery());

46.        dds.setTestOnBorrow(slaveProperties.isTestOnBorrow());

47.        dds.setTestWhileIdle(slaveProperties.isTestWhileIdle());

48.        dds.setTestOnReturn(slaveProperties.isTestOnReturn());

49.        dds.setPoolPreparedStatements(slaveProperties.isPoolPreparedStatements());

50.        dds.setMaxPoolPreparedStatementPerConnectionSize(

51.                slaveProperties.getMaxPoolPreparedStatementPerConnectionSize());

52.        dds.setFilters(slaveProperties.getFilters());

53.        return dds;

54.    }

55.    @Bean

56.    public ServletRegistrationBean druidServletRegistrationBean(EnvConfig env) {

57.        String username = env.getStringValue(DSConfig.DRUID_MONITOR_USERNAME);

58.        String password = env.getStringValue(DSConfig.DRUID_MONITOR_PASSWORD);

59.        return new ServletRegistrationBean(new DruidStatViewServlet(username, password),

60.                DSConfig.DRUID_MONITOR_URL);

61.    }

62.    @Bean

63.    public FilterRegistrationBean druidFilterRegistrationBean() {

64.        WebStatFilter wsf = new WebStatFilter();

65.        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();

66.        filterRegistrationBean.setFilter(wsf);

67.        filterRegistrationBean.setUrlPatterns(Arrays.asList(DSConfig.DRUID_FILTER_URL));

68.        filterRegistrationBean.setInitParameters(

69.                Collections.singletonMap("exclusions", DSConfig.DRUID_FILTER_EXCLUSIONS));

70.        return filterRegistrationBean;

71.    }

72. }

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：

1. @Configuration

2. @ComponentScan(basePackages = "com.example.common.config.properties")

3. public class PropertiesConfig {

4. }

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

连接池监控配置类：

1. public class DruidStatViewServlet extends StatViewServlet {

2.    private static final long serialVersionUID = 1L;

3.    private String username;

4.    private String password;

5.    @Override

6.    public String getInitParameter(String name) {

7.        if ("loginUsername".equals(name)) {

8.            return username;

9.        }

10.        if ("loginPassword".equals(name)) {

11.            return password;

12.        }

13.        return super.getInitParameter(name);

14.    }

15.    public DruidStatViewServlet(String username, String password) {

16.        super();

17.        this.username = username;

18.        this.password = password;

19.    }

20.    public String getUsername() {

21.        return username;

22.    }

23.    public String getPassword() {

24.        return password;

25.    }

26. }

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

1. org.springframework.boot.autoconfigure.EnableAutoConfiguration=\

2. com.example.common.config.ds.DruidAutoConfig

切换数据源

切换数据源注解：

1. @Target(ElementType.METHOD)

2. @Retention(RetentionPolicy.RUNTIME)

3. @Documented

4. public @interface DS {

5.    String value() default DSConfig.DB_MASTER;

6. }

动态数据源类：

1. public class DynamicDataSource extends AbstractRoutingDataSource {

2.    private final Logger logger = LoggerUtils.getLogger(this);

3.    @Override

4.    protected Object determineCurrentLookupKey() {

5.        logger.debug("当前数据源为{}", DataSourceContextHolder.getDS());

6.        return DataSourceContextHolder.getDS();

7.    }

8. }

动态数据源AOP实现类：

1. @Aspect

2. @Component

3. public class DynamicDataSourceAspect {

4.    @Before("@annotation(DS)")

5.    public void beforeSwitchDS(JoinPoint point) {

6.        Class<?> className = point.getTarget().getClass();

7.        String methodName = point.getSignature().getName();

8.        Class<?>[] argClass = ((MethodSignature) point.getSignature()).getParameterTypes();

9.        String dataSource = DataSourceContextHolder.DEFAULT_DS;

10.        try {

11.            Method method = className.getMethod(methodName, argClass);

12.            if (method.isAnnotationPresent(DS.class)) {

13.                DS annotation = method.getAnnotation(DS.class);

14.                dataSource = annotation.value();

15.            }

16.        } catch (Exception e) {

17.            e.printStackTrace();

18.        }

19.        DataSourceContextHolder.setDS(dataSource);

20.    }

21.    @After("@annotation(DS)")

22.    public void afterSwitchDS(JoinPoint point) {

23.        DataSourceContextHolder.clearDS();

24.    }

25. }

绑定当前线程数据源类：

1. public class DataSourceContextHolder {

2.    public static final String DEFAULT_DS = DSConfig.DB_MASTER;

3.    private static final ThreadLocal<String> DS_HOLDER = new ThreadLocal<>();

4.    public static void setDS(String dbType) {

5.        DS_HOLDER.set(dbType);

6.    }

7.    public static String getDS() {

8.        return (DS_HOLDER.get());

9.    }

10.    public static void clearDS() {

11.        DS_HOLDER.remove();

12.    }

13. }

-END-

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