对于动态切换数据源，需要一个类继承AbstractRoutingDataSource,继承该抽象类的时候，必须实现一个抽象方法：protected abstract Object determineCurrentLookupKey()，该方法用于指定到底需要使用哪一个数据源。
public abstract class AbstractRoutingDataSource extends AbstractDataSource implements InitializingBean {
private Map<Object, Object> targetDataSources;
private Object defaultTargetDataSource;
private boolean lenientFallback = true;
private DataSourceLookup dataSourceLookup = new JndiDataSourceLookup();
private Map<Object, DataSource> resolvedDataSources;
private DataSource resolvedDefaultDataSource;
public AbstractRoutingDataSource() {
}
public void setTargetDataSources(Map<Object, Object> targetDataSources) {
this.targetDataSources = targetDataSources;
}
public void setDefaultTargetDataSource(Object defaultTargetDataSource) {
this.defaultTargetDataSource = defaultTargetDataSource;
}
public void setLenientFallback(boolean lenientFallback) {
this.lenientFallback = lenientFallback;
}
public void setDataSourceLookup(DataSourceLookup dataSourceLookup) {
this.dataSourceLookup = (DataSourceLookup)(dataSourceLookup != null ? dataSourceLookup : new JndiDataSourceLookup());
}
public void afterPropertiesSet() {
if (this.targetDataSources == null) {
throw new IllegalArgumentException("Property 'targetDataSources' is required");
} else {
this.resolvedDataSources = new HashMap(this.targetDataSources.size());
Iterator var1 = this.targetDataSources.entrySet().iterator();
while(var1.hasNext()) {
Entry<Object, Object> entry = (Entry)var1.next();
Object lookupKey = this.resolveSpecifiedLookupKey(entry.getKey());
DataSource dataSource = this.resolveSpecifiedDataSource(entry.getValue());
this.resolvedDataSources.put(lookupKey, dataSource);
}
if (this.defaultTargetDataSource != null) {
this.resolvedDefaultDataSource = this.resolveSpecifiedDataSource(this.defaultTargetDataSource);
}
}
}
protected Object resolveSpecifiedLookupKey(Object lookupKey) {
return lookupKey;
}
protected DataSource resolveSpecifiedDataSource(Object dataSource) throws IllegalArgumentException {
if (dataSource instanceof DataSource) {
return (DataSource)dataSource;
} else if (dataSource instanceof String) {
return this.dataSourceLookup.getDataSource((String)dataSource);
} else {
throw new IllegalArgumentException("Illegal data source value - only [javax.sql.DataSource] and String supported: " + dataSource);
}
}
public Connection getConnection() throws SQLException {
return this.determineTargetDataSource().getConnection();
}
public Connection getConnection(String username, String password) throws SQLException {
return this.determineTargetDataSource().getConnection(username, password);
}
public <T> T unwrap(Class<T> iface) throws SQLException {
return iface.isInstance(this) ? this : this.determineTargetDataSource().unwrap(iface);
}
public boolean isWrapperFor(Class<?> iface) throws SQLException {
return iface.isInstance(this) || this.determineTargetDataSource().isWrapperFor(iface);
}
protected DataSource determineTargetDataSource() {
Assert.notNull(this.resolvedDataSources, "DataSource router not initialized");
Object lookupKey = this.determineCurrentLookupKey();
DataSource 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 + "]");
} else {
return dataSource;
}
}
protected abstract Object determineCurrentLookupKey();
}
自定义动态数据源类
import com.example.savesearchservice.util.DataSourceUtil;
import com.example.savesearchservice.util.DynamicDatasourceHolder;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.boot.jdbc.DataSourceBuilder;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import javax.sql.DataSource;
public class DynamicDataSource extends AbstractRoutingDataSource {
private static final Log logger = LogFactory.getLog(DynamicDataSource.class);
private static Map<Object, Object> datasourceMap = new ConcurrentHashMap<>();
@Override
protected Object determineCurrentLookupKey() {
logger.info("current dataSourceId:" + DynamicDatasourceHolder.get());
return DynamicDatasourceHolder.get();
}
public DataSource createDatasource(String id, String url, String username, String password, String driverClassName) {
DataSource dataSource = DataSourceBuilder.create()
.url(url)
.username(username)
.password(password)
.driverClassName(driverClassName)
.build();
if (dataSource != null) {
DataSourceUtil.put(id, id);
datasourceMap.put(id, dataSource);
//调用父类方法赋值Map<Object, DataSource> resolvedDataSources
super.setTargetDataSources(datasourceMap);
super.afterPropertiesSet();
return dataSource;
}
return null;
}
}
通过ThreadLocal维护一个全局唯一的map来实现数据源的动态切换
public class DynamicDatasourceHolder {
private static final ThreadLocal<String> DATASOURCE_HOLDER = new ThreadLocal<>();
public static void add(String datasource) {
DATASOURCE_HOLDER.set(datasource);
}
public static String get() {
return DATASOURCE_HOLDER.get();
}
public static void clear() {
DATASOURCE_HOLDER.remove();
}
}
通过AOP切面实现动态切换数据源，这里假设projectId与dataSourceId有对应关系
import com.example.savesearchservice.annotation.DataSource;
import com.example.savesearchservice.datasource.DynamicDataSource;
import com.example.savesearchservice.util.DataSourceUtil;
import com.example.savesearchservice.util.DynamicDatasourceHolder;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;
@Component
@Aspect
@Order(-1)
public class DynamicDataSourceAOP implements ApplicationContextAware {
private static final Log logger = LogFactory.getLog(DynamicDataSourceAOP.class);
private ApplicationContext applicationContext;
@Pointcut("execution(* com.example.controller*(..))")
public void pointCut() {
}
/**
* 执行方法前更换数据源
*
* @param joinPoint 切点
*/
@Before("@annotation(dataSource)")
public void doBefore(JoinPoint joinPoint, DataSource dataSource) {
logger.info("Enter DataSourceAOP");
String projectId = DataSourceUtil.DEFAULT;
Object[] args = joinPoint.getArgs();
if (args.length >= 1) {
projectId = String.valueOf(args[0]);
}
projectId = StringUtils.defaultIfBlank(projectId, DataSourceUtil.DEFAULT);
if (!DataSourceUtil.contains(projectId)) {
DynamicDataSource dynamicDataSource = applicationContext.getBean(DynamicDataSource.class);
//这里可以根据需要从数据库或者其他地方获取数据源连接信息
dynamicDataSource.createDatasource(projectId,
"jdbc:mysql://localhost:3306/dynamic_datasource?useSSL=true&useUnicode=true&characterEncoding=utf8",
"XXX", "XXX", "com.mysql.cj.jdbc.Driver");
DynamicDatasourceHolder.add(DataSourceUtil.getDataSourceId(projectId));
logger.info(String.format("change dataSource for %s,dataSourceId: %s", projectId, DataSourceUtil.getDataSourceId(projectId)));
return;
}
DynamicDatasourceHolder.add(DataSourceUtil.getDataSourceId(projectId));
}
/**
* 执行方法后清除数据源设置
*
* @param joinPoint 切点
*/
@After("@annotation(dataSource)")
public void doAfter(JoinPoint joinPoint, DataSource dataSource) {
DynamicDatasourceHolder.clear();
}
@Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
this.applicationContext = applicationContext;
}
}
新建DataSourceUtil类保存projectId与dataSourceId的对应关系
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
public class DataSourceUtil {
public static final String DEFAULT = "default";
private static final Map<String, String> dataSourceMap = new ConcurrentHashMap<>();
private DataSourceUtil() {
}
public static void put(String projectId, String dataSource) {
dataSourceMap.put(projectId, dataSource);
}
public static boolean contains(String projectId) {
return dataSourceMap.get(projectId) != null;
}
public static String getDataSourceId(String projectId) {
return dataSourceMap.get(projectId);
}
}
springboot启动时的配置类配置默认datasource
import com.example.savesearchservice.datasource.DynamicDataSource;
import com.example.savesearchservice.util.DataSourceUtil;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.annotation.MapperScan;
import org.mybatis.spring.mapper.MapperScannerConfigurer;
import org.springframework.context.EnvironmentAware;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;
import org.springframework.core.io.ClassPathResource;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import javax.sql.DataSource;
import lombok.NonNull;
@Configuration
@MapperScan("com.example.savesearchservice.dao")
public class DataSourceConfiguration implements EnvironmentAware {
private static Log logger = LogFactory.getLog(DataSourceConfiguration.class);
private Environment environment;
@Bean
DataSource dataSource() {
logger.info("environment:" + environment);
DynamicDataSource dynamicDataSource = new DynamicDataSource();
DataSource dataSource = dynamicDataSource.createDatasource(DataSourceUtil.DEFAULT,
environment.getProperty("datasource.url"),
environment.getProperty("datasource.username"),
environment.getProperty("datasource.password"),
environment.getProperty("datasource.driver-class-name"));
dynamicDataSource.setDefaultTargetDataSource(dataSource);
return dynamicDataSource;
}
@Bean
SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {
SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
sqlSessionFactoryBean.setDataSource(dataSource);
sqlSessionFactoryBean.setConfigLocation(new ClassPathResource("mybatis/mybatis-conf.xml"));
return sqlSessionFactoryBean.getObject();
}
@Bean
MapperScannerConfigurer mapperScannerConfigurer() {
MapperScannerConfigurer mapperScannerConfigurer = new MapperScannerConfigurer();
mapperScannerConfigurer.setAnnotationClass(com.example.savesearchservice.annotation.DataSource.class);
mapperScannerConfigurer.setBasePackage("com.example.savesearchservice.dao");
mapperScannerConfigurer.setSqlSessionFactoryBeanName("sqlSessionFactory");
return mapperScannerConfigurer;
}
@Bean
DataSourceTransactionManager dataSourceTransactionManager(DataSource dataSource) {
DataSourceTransactionManager dataSourceTransactionManager = new DataSourceTransactionManager();
dataSourceTransactionManager.setDataSource(dataSource);
return dataSourceTransactionManager;
}
@Override
public void setEnvironment(@NonNull Environment environment) {
this.environment = environment;
}
}
可以看到，已经实现了数据源的动态切换
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