英协网作者：不羁码农
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)
@Documented
public @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
@Component
public 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();
}
}
