谈谈Spring Boot 数据源加载及其多数据源简单实现(小结)

// 默认的事务管理器
ppublic class DataSourceTransactionManager extends AbstractPlatformTransactionManager
  implements ResourceTransactionManager, InitializingBean {
 
 // 启动时候注入一个数据源
 public void setDataSource(@Nullable DataSource dataSource) {
  if (dataSource instanceof TransactionAwareDataSourceProxy) {
   this.dataSource = ((TransactionAwareDataSourceProxy) dataSource).getTargetDataSource();
  }
  else {
   this.dataSource = dataSource;
  }
 }
」

public abstract class AbstractRoutingDataSource extends AbstractDataSource implements InitializingBean {
 
 // 用户设置的全部的数据源配置
 @Nullable
 private Map<Object, Object> targetDataSources;
 // 为空默认的数据源配置
 @Nullable
 private Object defaultTargetDataSource;
 
 // 路由键查找实现
 private DataSourceLookup dataSourceLookup = new JndiDataSourceLookup();
 
 // 最终有效的数据源配置（一般清空对应上边用户的设置）
 @Nullable
 private Map<Object, DataSource> resolvedDataSources;
}

@Slf4j
public class DynamicDataSource extends AbstractRoutingDataSource {

 /**
  * 指定路由Key,这里很简单 获取 threadLocal 中目标key 即可
  *
  * @return
  */
 @Override
 protected Object determineCurrentLookupKey() {
  return DynamicDataSourceContextHolder.getDataSourceType();
 }
}

@Slf4j
@Configuration
@AllArgsConstructor
public class DynamicDataSourceConfig implements TransactionManagementConfigurer {
 private final Map<Object, Object> dataSourceMap = new HashMap<>(8);
 private final DataSourceProperties dataSourceProperties;

 @Bean("dynamicDataSource")
 public DynamicDataSource dataSource() {
  JdbcTemplate(dds).queryForList(DataSourceConstant.QUERY_DS_SQL);
  log.info("开始 -> 初始化动态数据源");
  Optional.of(dbList).ifPresent(list -> list.forEach(db -> {
   log.info("数据源:{}", db.get(DataSourceConstant.DS_NAME));
   HikariDataSource ds = new HikariDataSource();
   dataSourceMap.put(db.get(DataSourceConstant.DS_ROUTE_KEY), ds);
  }));
  
  DynamicDataSource ds = new DynamicDataSource();
  ds.setTargetDataSources(dataSourceMap);
  return ds;
 }

 @Bean
 public PlatformTransactionManager txManager() {
  return new DataSourceTransactionManager(dataSource());
 }

 @Override
 public PlatformTransactionManager annotationDrivenTransactionManager() {
  return txManager();
 }

}

DynamicDataSourceContextHolder.setDataSourceType（key）

public class DynamicDataSourceConfig implements TransactionManagementConfigurer {
 private final Map<Object, Object> dataSourceMap = new HashMap<>(8);
 private final DataSourceProperties dataSourceProperties;
 private final StringEncryptor stringEncryptor;

 @Bean("dynamicDataSource")
 public DynamicDataSource dataSource() {
  DynamicDataSource ds = new DynamicDataSource();
  HikariDataSource cads = new HikariDataSource();
  cads.setJdbcUrl(dataSourceProperties.getUrl());
  cads.setDriverClassName(dataSourceProperties.getDriverClassName());
  cads.setUsername(dataSourceProperties.getUsername());
  cads.setPassword(dataSourceProperties.getPassword());
  ds.setDefaultTargetDataSource(cads);
  dataSourceMap.put(0, cads);
  ds.setTargetDataSources(dataSourceMap);
  return ds;
 }

 /**
  * 组装默认配置的数据源，查询数据库配置
  */
 @PostConstruct
 public void init() {
  DriverManagerDataSource dds = new DriverManagerDataSource();
  dds.setUrl(dataSourceProperties.getUrl());
  dds.setDriverClassName(dataSourceProperties.getDriverClassName());
  dds.setUsername(dataSourceProperties.getUsername());
  dds.setPassword(dataSourceProperties.getPassword());

  List<Map<String, Object>> dbList = new JdbcTemplate(dds).queryForList(DataSourceConstant.QUERY_DS_SQL);
  log.info("开始 -> 初始化动态数据源");
  Optional.of(dbList).ifPresent(list -> list.forEach(db -> {
   log.info("数据源:{}", db.get(DataSourceConstant.DS_NAME));
   HikariDataSource ds = new HikariDataSource();
   ds.setJdbcUrl(String.valueOf(db.get(DataSourceConstant.DS_JDBC_URL)));
   ds.setDriverClassName(Driver.class.getName());
   ds.setUsername((String) db.get(DataSourceConstant.DS_USER_NAME));

   String decPwd = stringEncryptor.decrypt((String) db.get(DataSourceConstant.DS_USER_PWD));
   ds.setPassword(decPwd);
   dataSourceMap.put(db.get(DataSourceConstant.DS_ROUTE_KEY), ds);
  }));

  log.info("完毕 -> 初始化动态数据源,共计 {} 条", dataSourceMap.size());
 }

 /**
  * 重新加载数据源配置
  */
 public Boolean reload() {
  init();
  DynamicDataSource dataSource = dataSource();
  dataSource.setTargetDataSources(dataSourceMap);
  dataSource.afterPropertiesSet();
  return Boolean.FALSE;
 }


 @Bean
 public PlatformTransactionManager txManager() {
  return new DataSourceTransactionManager(dataSource());
 }

 @Override
 public PlatformTransactionManager annotationDrivenTransactionManager() {
  return txManager();
 }