数据库连接失败,如何重新进行正确配置？

Posted 2023-04-22

参考技术A

方法如下：

检查服务是否启动

1、在SQLServer服务器中， 打开SQLServer服务管理器。单击【开始】-【程序】-【Microsoft SQLServer】-【服务管理器】菜单命令。

2、打开【SQLServer服务管理器】，单击【服务器】，选择要检查的SQLServer的实例名【abc10-1DA235E90】，单击【服务】，选择【SQLServer】选项，如果此时暂停或者停止按钮可用，说明服务已经启动；否则则没有启动，启动即可。

3、最好在【SQLServer服务管理器】中将选择随系统启动而启动服务。选择【当启动OS时自动启动服务】选择框，完成让MSSQLSERVER服务随操作系统启动而自动启动。

4、再次打开SQL Server 数据库，选择连接数据库服务器实例，可以正常连接打开数据库了。

5、SQL Server数据库能正常连接得保证网络通畅，操作过程中还需要进行网络测试，可以通过PING命令实现。如下图所示，表示网络通畅。

如何重新连接okhttp-ws

【中文标题】如何重新连接okhttp-ws

【英文标题】：How to reconnect okhttp-ws

【发布时间】：2021-10-11 04:21:54

【问题描述】：

如果IP地址改变或连接失败，如何正确重新连接？

我正在尝试重新连接 okhttp-ws

.....

    @Override
    public void onFailure(IOException e, okhttp3.Response response) 
      try 
               connecting();
             catch (Exception e1) 
            Timber.e(e1, "onFailure");
        
    

    @Override
    public void onClose(int code, String reason) 
        Timber.d("Connection unexpectedly closed");
        connecting();
    

    public void connecting() 
    if (wsClient == null) 
        wsClient = builder.build();
    if (call != null) call.cancel();
    call = WebSocketCall.create(wsClient, request);
    try 
        lock.lockInterruptibly();
        try   call.enqueue(listener);
         finally 
            lock.unlock();
        
     catch (InterruptedException e) 
        Timber.e(e, "connecting error");
    

我收到一个错误

java.lang.RuntimeException: 无法启动服务...（有 额外）：java.util.concurrent.RejectedExecutionException：任务 okhttp3.RealCall$AsyncCall@3f946389 被拒绝 java.util.concurrent.ThreadPoolExecutor@d784f8e[终止，池大小 = 0，活动线程 = 0，排队任务 = 0，已完成任务 = 1] 在 android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3320)

【参考方案1】：

看例子和我的简单library

...
try
WebsocketClient.dispatcher().cancelAll();// to cancel all requests
...

在失败时触发 ( ... ) 您可以重新连接

【参考方案2】：

   /**
     * Configure this client to retry or not when a connectivity problem is encountered. By default,
     * this client silently recovers from the following problems:
     *
     * <ul>
     *   <li><strong>Unreachable IP addresses.</strong> If the URL's host has multiple IP addresses,
     *       failure to reach any individual IP address doesn't fail the overall request. This can
     *       increase availability of multi-homed services.
     *   <li><strong>Stale pooled connections.</strong> The @link ConnectionPool reuses sockets
     *       to decrease request latency, but these connections will occasionally time out.
     *   <li><strong>Unreachable proxy servers.</strong> A @link ProxySelector can be used to
     *       attempt multiple proxy servers in sequence, eventually falling back to a direct
     *       connection.
     * </ul>
     *
     * Set this to false to avoid retrying requests when doing so is destructive. In this case the
     * calling application should do its own recovery of connectivity failures.
     */

    OkHttpClient.Builder builder = new OkHttpClient.Builder();
    builder.retryOnConnectionFailure(true);

【讨论】：

我试过这个用于网络套接字，不幸的是它没有重新连接网络套接字