spring boot实现程序运行过程中数据源动态切换

项目中有一个需求，spring boot项目连接postgres数据库的地址，是存储在etcd当中的，在程序启动后，当etcd中的地址变化时，需要程序去连接新的postgres地址。

修改Datasource定义，改为使用DynamicPGDataSource，它是一个自定义类，集成了

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AbstractRoutingDataSource

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@Primary
    @Bean
    public DataSource druidDataSource() {
        DruidDataSource druidDataSource = DruidDataSourceBuilder.create().build();
        druidDataSource.setUrl(url);
        druidDataSource.setUsername(username);
        druidDataSource.setPassword(password);
        druidDataSource.setDriverClassName(driverClassName);
        druidDataSource.setInitialSize(druidInitSize);// 初始化连接数
        druidDataSource.setMinIdle(druidMinIdle); // 最小连接数
        druidDataSource.setMaxActive(druidMaxActive);// 最大连接数
        druidDataSource.setPoolPreparedStatements(true);// 开启缓存preparedStatement
        druidDataSource.setUseGlobalDataSourceStat(true);

        // 开启Druid提供的3s慢SQL监控
        Properties properties = new Properties();
        properties.put("druid.stat.mergeSql", true);
        properties.put("druid.stat.slowSqlMillis", 3000);
        druidDataSource.setConnectProperties(properties);
        try {
            druidDataSource.setFilters("stat,wall");
            druidDataSource.init();
        } catch (SQLException e) {
            log.error("构建数据库连接池异常，异常原因：{}", e);
            throw new RuntimeException(e);
        }

        DynamicPGDataSource dynamicPGDataSource = new DynamicPGDataSource();
        Map<Object, Object> targetDataSources = new HashMap<>();
        targetDataSources.put(ConnectInfo.currentPGIP, druidDataSource);
        dynamicPGDataSource.setTargetDataSources(targetDataSources);
        dynamicPGDataSource.setDefaultTargetDataSource(druidDataSource);
        return dynamicPGDataSource;
    }

类定义

public class DynamicPGDataSource extends AbstractRoutingDataSource {
@Override
protected Object determineCurrentLookupKey() {
return DataSourceContext.getPGDataSource();
}
}

public class DataSourceContext {
private static String pgDataSource;
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```
 public static void setPGDataSource(String ds) {
     pgDataSource = ds;
 }

 public static String getPGDataSource() {
     return pgDataSource;
 }
```
}

定义re方法，当监听到数据源IP更改之后，去切换连接到新的数据源，并且关闭老的数据源连接。

public void refreshPGDataSource(String ip) {
if(ConnectInfo.currentPGIP.equals(ip)) {
log.info("currentPGIP equals ip, not operate, ip:{}", ip);
}
DynamicPGDataSource dynamicPGDataSource = ((DynamicPGDataSource)druidDataSource);
Field field = null;
try {
field = AbstractRoutingDataSource.class.getDeclaredField("targetDataSources");
} catch (NoSuchFieldException e) {
e.printStackTrace();
}
field.setAccessible(true);

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     // 获取当前的 targetDataSources
     Map<Object, Object> currentDataSources = null;
     try {
         currentDataSources = (Map<Object, Object>) field.get(dynamicPGDataSource);
         if(!currentDataSources.containsKey(ip)) {
             DruidDataSource druidDataSource = DruidDataSourceBuilder.create().build();
             String address = String.format("jdbc:postgresql://%s:5432/dsgdb?characterEncoding=utf-8&useSSL=false", ip);
             druidDataSource.setUrl(address);
             druidDataSource.setUsername(username);
             druidDataSource.setPassword(password);
             druidDataSource.setDriverClassName(driverClassName);
             druidDataSource.setInitialSize(20);// 初始化连接数
             druidDataSource.setMinIdle(10); // 最小连接数
             druidDataSource.setMaxActive(100);// 最大连接数
             druidDataSource.setPoolPreparedStatements(true);// 开启缓存preparedStatement
             druidDataSource.setUseGlobalDataSourceStat(true);
             // 开启Druid提供的3s慢SQL监控
             Properties properties = new Properties();
             properties.put("druid.stat.mergeSql", true);
             properties.put("druid.stat.slowSqlMillis", 3000);
             druidDataSource.setConnectProperties(properties);
             druidDataSource.setFilters("stat,wall");
             currentDataSources.put(ip, druidDataSource);
             field.set(dynamicPGDataSource, currentDataSources);
             dynamicPGDataSource.afterPropertiesSet();
         }
         DataSourceContext.setPGDataSource(ip);
         ConnectInfo.currentPGIP = ip;
         // 关闭无用连接
         Iterator<Map.Entry<Object, Object>> iterator = currentDataSources.entrySet().iterator();
         while (iterator.hasNext()) {
             Map.Entry<Object, Object> entry = iterator.next();
             if(!ip.equals(entry.getKey())) {
                 DruidDataSource dataSource = (DruidDataSource)currentDataSources.get(entry.getKey());
                 dataSource.close();
                 iterator.remove();
             }
         }
     } catch (IllegalAccessException | SQLException e) {
         e.printStackTrace();
     }
 }