标签：imp 开源 动态切换 template val 授权 property nec cti
参考RuoYi开源项目https://gitee.com/y_project/RuoYi.git 动态数据库
在一个普通Spring + Mybatis项目中，如果使用了多数据源，可以通过在dao层注入不同的SqlSessionTemplate来实现与不同数据库交互的目的。单个SqlSessionTemplate注入容器的过程如下：
<!-- 配置数据源 -->
<bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
<property name="driverClassName" value="${jdbc.driver}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</bean>
<!-- 注册sqlSessionFactory -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource"/>
<property name="configLocation" value="classpath:config/mybatis-config.xml"/>
<property name="typeAliasesPackage" value="com.wch.base.domain"/>
<property name="mapperLocations" value="classpath:mapper/*.xml"/>
</bean>
<!-- 配置dao接口扫描，配置sqlSessionTemplate -->
<context:component-scan base-package="com.wch.base.mapper"/>
<bean id="sqlSessionTemplate" class="org.mybatis.spring.SqlSessionTemplate">
<constructor-arg ref="sqlSessionFactory"/>
</bean>
如果项目需要连接多个数据源，从DataSource、SqlSessionFactory、SqlSessionTemplate都需要配置多次，难于维护和管理。
AbstractRoutingDataSource是spring-jdbc包提供的一个了AbstractDataSource的抽象类，它实现了DataSource接口的用于获取数据库连接的方法。
@Override
public Connection getConnection() throws SQLException {
return determineTargetDataSource().getConnection();
}
@Override
public Connection getConnection(String username, String password) throws SQLException {
return determineTargetDataSource().getConnection(username, password);
}
protected DataSource determineTargetDataSource() {
Assert.notNull(this.resolvedDataSources, "DataSource router not initialized");
// 获取指定数据源关键字
Object lookupKey = determineCurrentLookupKey();
DataSource dataSource = this.resolvedDataSources.get(lookupKey);
if (dataSource == null && (this.lenientFallback || lookupKey == null)) {
dataSource = this.resolvedDefaultDataSource;
}
if (dataSource == null) {
throw new IllegalStateException("Cannot determine target DataSource for lookup key [" + lookupKey + "]");
}
return dataSource;
}
public void setTargetDataSources(Map<Object, Object> targetDataSources) {
this.targetDataSources = targetDataSources;
}
AbstractRoutingDataSource的内部维护了一个名为targetDataSources的Map，并提供的setter方法用于设置数据源关键字与数据源的关系，实现类被要求实现其determineCurrentLookupKey()方法，由此方法的返回值决定具体从哪个数据源中获取连接。
AbstractRoutingDataSource提供了程序运行时动态切换数据源的方法，在dao类或方法上标注需要访问数据源的关键字，路由到指定数据源，获取连接。
维护一个static变量datasourceContext用于记录每个线程需要使用的数据源关键字。并提供切换、读取、清除数据源配置信息的方法。
@Slf4j
public class DataSourceContextHolder {
private static ThreadLocal<String> datasourceContext = new ThreadLocal<>();
public static void switchDataSource(String datasource) {
log.debug("switchDataSource: {}", datasource);
datasourceContext.set(datasource);
}
public static String getDataSource() {
return datasourceContext.get();
}
public static void clear() {
datasourceContext.remove();
}
}
public class RoutingDataSource extends AbstractRoutingDataSource {
@Override
protected Object determineCurrentLookupKey() {
return DataSourceContextHolder.getDataSource();
}
}
# master datasource
ds.financial.master.driverClassName=com.mysql.jdbc.Driver
ds.financial.master.url=jdbc:mysql://127.0.0.1:3306/financial?useUnicode=true&characterEncoding=utf8&useSSL=true
ds.financial.master.username=root
ds.financial.master.password=
ds.financial.master.type=com.alibaba.druid.pool.DruidDataSource
# slave datasource
ds.financial.slave.driverClassName=com.mysql.jdbc.Driver
ds.financial.slave.url=jdbc:mysql://127.0.0.1:3306/financial_slave?useUnicode=true&characterEncoding=utf8&useSSL=true
ds.financial.slave.username=root
ds.financial.slave.password=
ds.financial.slave.type=com.alibaba.druid.pool.DruidDataSource
@Configuration
public class DataSourceConfig {
@Bean
@Primary
@ConfigurationProperties(prefix = "ds.financial.master")
public DataSource financialMasterDataSource() {
return DataSourceBuilder.create().build();
}
@Bean
@ConfigurationProperties(prefix = "ds.financial.slave")
public DataSource financialSlaveDataSource() {
return DataSourceBuilder.create().build();
}
@Bean(name = "routingDataSource")
public RoutingDataSource routingDataSource() {
Map<Object, Object> dataSourceMap = new HashMap<>();
dataSourceMap.put("financial-master", financialMasterDataSource());
dataSourceMap.put("financial-slave", financialSlaveDataSource());
RoutingDataSource routingDataSource = new RoutingDataSource();
routingDataSource.setTargetDataSources(dataSourceMap);
routingDataSource.setDefaultTargetDataSource(financialMasterDataSource());
return routingDataSource;
}
}
@Configuration
public class MyBatisConfig {
@Resource(name = "routingDataSource")
private RoutingDataSource routingDataSource;
/**
* routingDataSource sqlSessionFactory
*
* @return
*/
@Bean
public SqlSessionFactory sqlSessionFactory() throws Exception {
SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
sqlSessionFactoryBean.setDataSource(routingDataSource);
sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mapper/**/*.xml"));
sqlSessionFactoryBean.setTypeAliasesPackage("com.wch.financial.domain");
return sqlSessionFactoryBean.getObject();
}
/**
* 注册 sqlSessionTemplate
*
* @param sqlSessionFactory
* @return
*/
@Bean
public SqlSessionTemplate financialMasterSqlSessionTemplate(SqlSessionFactory sqlSessionFactory) {
return new SqlSessionTemplate(sqlSessionFactory);
}
}
当一个线程执行某个dao方法时读取此方法配置的数据源关键字并写入datasourceContext，在此方法执行完成后清除datasourceContext中的标记。此生命周期使用aop实现。
用于dao类或方法上。
@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface DataSource {
String name() default "";
}
@Aspect
@Component
public class HandleDatasourceAspect {
@Pointcut("@annotation(com.wch.financial.config.DataSource)")
public void pointcut() {
}
@Before("pointcut()")
public void beforeExecute(JoinPoint joinPoint) {
Method method = ((MethodSignature) joinPoint.getSignature()).getMethod();
DataSource annotation = method.getAnnotation(DataSource.class);
if (null == annotation) {
annotation = joinPoint.getTarget().getClass().getAnnotation(DataSource.class);
}
if (null != annotation) {
// 切换数据源
DataSourceContextHolder.switchDataSource(annotation.name());
}
}
@After("pointcut()")
public void afterExecute() {
DataSourceContextHolder.clear();
}
}
在dao实现类的类或方法上标注@DataSource注解。
@Repository
public class ProductDaoImpl implements ProductDao {
@Resource
private SqlSessionTemplate sst;
@Override
@DataSource(name = "financial-slave")
public List<Product> selectProduct() {
return sst.selectList("financial.product.selectProduct");
}
}AbstractRoutingDataSource -- Spring提供的轻量级数据源切换方式
标签：imp 开源 动态切换 template val 授权 property nec cti
原文地址：https://www.cnblogs.com/hfultrastrong/p/12176030.html
