1.使用
1)写一个DynamicDataSource类继承AbstractRoutingDataSource
public class DynamicDataSource extends AbstractRoutingDataSource { @Override protected Object determineCurrentLookupKey() { return DSNameHolder.getDSName(); } /** * used for test * @return */ public DataSource getCurrentDataSource() { return super.determineTargetDataSource(); } }
2) DSNameHolder
public class DSNameHolder { public static ThreadLocal<String> DS_NAME_HOLDER = new ThreadLocal<String>(); public static void setDSName(String dsName) { DS_NAME_HOLDER.set(dsName); } public static String getDSName() { return DS_NAME_HOLDER.get(); } }
3)测试
spring-ds.xml
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"> <bean name="datasource" class="com.siyuan.study.spring.jdbc.DynamicDataSource"> <property name="targetDataSources"> <map> <entry key="ds_a" value-ref="datasource_a"/> <entry key="ds_b" value-ref="datasource_b"/> </map> </property> <property name="defaultTargetDataSource" ref="datasource_a"/> </bean> <bean id="datasource_a" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="url" value="jdbc:mysql://localhost:3306;databaseName=test_a" /> <property name="driverClassName" value="com.mysql.jdbc.Driver" /> <property name="username" value="root" /> <property name="password" value="123456" /> </bean> <bean id="datasource_b" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="url" value="jdbc:mysql://localhost:3306;databaseName=test_b" /> <property name="driverClassName" value="com.mysql.jdbc.Driver" /> <property name="username" value="root" /> <property name="password" value="123456" /> </bean> </beans>
DynamicDataSourceTest
public class DynamicDataSourceTest { private ApplicationContext ctxt; @Before public void setup() { ctxt = new ClassPathXmlApplicationContext("spring-ds.xml"); } @Test public void getConnection() { DynamicDataSource datasource = (DynamicDataSource) ctxt.getBean("datasource"); DataSource datasource_a = (DataSource) ctxt.getBean("datasource_a"); DataSource datasource_b = (DataSource) ctxt.getBean("datasource_b"); assertSame(datasource_a, datasource.getCurrentDataSource()); //switch to ds_b DSNameHolder.setDSName("ds_b"); assertSame(datasource_b, datasource.getCurrentDataSource()); //switch to ds_a DSNameHolder.setDSName("ds_a"); assertSame(datasource_a, datasource.getCurrentDataSource()); } }
2.源码分析
1)afterPropertiesSet
public void afterPropertiesSet() { if (this.targetDataSources == null) { throw new IllegalArgumentException("Property 'targetDataSources' is required"); } this.resolvedDataSources = new HashMap<Object, DataSource>(this.targetDataSources.size()); for (Map.Entry entry : this.targetDataSources.entrySet()) { Object lookupKey = resolveSpecifiedLookupKey(entry.getKey()); DataSource dataSource = resolveSpecifiedDataSource(entry.getValue()); this.resolvedDataSources.put(lookupKey, dataSource); } if (this.defaultTargetDataSource != null) { this.resolvedDefaultDataSource = resolveSpecifiedDataSource(this.defaultTargetDataSource); } }
2)getConnection
public Connection getConnection() throws SQLException { return determineTargetDataSource().getConnection(); } public Connection getConnection(String username, String password) throws SQLException { return determineTargetDataSource().getConnection(username, password); }
3)determineTargetDataSource
protected DataSource determineTargetDataSource() { Assert.notNull(this.resolvedDataSources, "DataSource router not initialized"); 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; }
3.参考资料
http://blog.163.com/wang_hj138@126/blog/static/140800106201263151242338/
http://www.360doc.com/content/13/1016/15/14212114_321868950.shtml