数据库连接问题 - 原因：java.sql.SQLRecoverableException: IO Error: Unknown host specified答案

【问题标题】：Database connection problem - Caused by: java.sql.SQLRecoverableException: IO Error: Unknown host specified数据库连接问题 - 原因：java.sql.SQLRecoverableException: IO Error: Unknown host specified
【发布时间】：2020-02-10 06:29:19
【问题描述】：

我们在生产实例中突然遇到数据库连接问题。重新启动后，应用程序再次运行。

这是堆栈跟踪

06 Feb 2020 11:11:37,714 [http-nio-6060-exec-21] ERROR IntegrationDAOImpl : authenticate user failed
org.hibernate.exception.JDBCConnectionException: Cannot open connection
    at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:74)
    at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
    at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:29)
    at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:426)
    at org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:144)
    at org.hibernate.jdbc.AbstractBatcher.prepareQueryStatement(AbstractBatcher.java:139)
    at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1547)
    at org.hibernate.loader.Loader.doQuery(Loader.java:673)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:236)
    at org.hibernate.loader.Loader.doList(Loader.java:2220)
    at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2104)
    at org.hibernate.loader.Loader.list(Loader.java:2099)
    at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:289)
    at org.hibernate.impl.SessionImpl.listCustomQuery(SessionImpl.java:1695)
    at org.hibernate.impl.AbstractSessionImpl.list(AbstractSessionImpl.java:142)
    at org.hibernate.impl.SQLQueryImpl.list(SQLQueryImpl.java:152)
    at com.base.action.user.LoginUserAction.loginTouch(LoginUserAction.java:387)
    at sun.reflect.GeneratedMethodAccessor1753.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:441)
    at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:280)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:243)
    at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:165)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:252)
    at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:122)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:179)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:94)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:235)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:89)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:130)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:267)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:126)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:138)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:165)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:179)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:176)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52)
    at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:488)
    at org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:395)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:678)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:367)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:860)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1598)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.sql.SQLRecoverableException: IO Error: Unknown host specified 
    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:743)
    at oracle.jdbc.driver.PhysicalConnection.connect(PhysicalConnection.java:666)
    at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32)
    at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:566)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriverManager(DriverManagerDataSource.java:283)
    at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriverManager(DriverManagerDataSource.java:271)
    at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriverManager(DriverManagerDataSource.java:255)
    at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:236)
    at org.springframework.orm.hibernate3.LocalDataSourceConnectionProvider.getConnection(LocalDataSourceConnectionProvider.java:81)
    at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:423)
    ... 85 more
Caused by: oracle.net.ns.NetException: Unknown host specified 
    at oracle.net.resolver.HostnameNamingAdapter.resolve(HostnameNamingAdapter.java:207)
    at oracle.net.resolver.NameResolver.resolveName(NameResolver.java:131)
    at oracle.net.resolver.AddrResolution.resolveAndExecute(AddrResolution.java:475)
    at oracle.net.ns.NSProtocol.establishConnection(NSProtocol.java:595)
    at oracle.net.ns.NSProtocol.connect(NSProtocol.java:230)
    at oracle.jdbc.driver.T4CConnection.connect(T4CConnection.java:1452)
    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:496)
    ... 96 more

我们正在同一台服务器上运行另一个套接字应用程序。我们也面临与应用程序相同的错误。这是我们第二个应用程序的日志

2020-02-06 11:05:18,589 [pool-2-thread-4] 
ERROR DbConnection : Db error
java.sql.SQLRecoverableException: IO Error: Unknown host specified 
    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:743)
    at oracle.jdbc.driver.PhysicalConnection.connect(PhysicalConnection.java:666)
    at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32)
    at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:566)
    at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:677)
    at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:228)
    at utils.DbConnection.getConnection(DbConnection.java:25)
    at requestValidation.validatePcbEnd(PanaCIMRequestValidation.java:812)
    at xmlConvert.ConvertReceivedXMLToObject.extractMaterialReqXmlToObjects(ConvertReceivedXMLToObject.java:73)
    at clientapplication.SendResponseToClient.run(SendResponseToClient.java:68)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    at java.base/java.lang.Thread.run(Thread.java:835)
Caused by: oracle.net.ns.NetException: Unknown host specified 
    at oracle.net.resolver.HostnameNamingAdapter.resolve(HostnameNamingAdapter.java:207)
    at oracle.net.resolver.NameResolver.resolveName(NameResolver.java:131)
    at oracle.net.resolver.AddrResolution.resolveAndExecute(AddrResolution.java:475)
    at oracle.net.ns.NSProtocol.establishConnection(NSProtocol.java:595)
    at oracle.net.ns.NSProtocol.connect(NSProtocol.java:230)
    at oracle.jdbc.driver.T4CConnection.connect(T4CConnection.java:1452)
    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:496)
    ... 12 more

但是在那段时间，我们可以使用 Sql developer 建立与数据库的连接。

这可能是什么问题？我们如何避免它？

这里是连接字符串，

jdbc:oracle:thin:@SERVERNAME:1521/test JDBC：https://mvnrepository.com/artifact/com.oracle/ojdbc7/12.1.0.2

【问题讨论】：

你有问题吗？
@ScaryWombat 感谢您宝贵的时间。我们需要了解错误发生的原因以及我们如何避免它。
它说 Unknown host specified 所以你真的需要告诉你是如何连接的。你是远程连接吗？使用 DNS？也许只是有一个脆弱的网络
@ScaryWombat 我们使用 DNS 连接，这里是连接字符串 jdbc:oracle:thin:@SERVERNAME:1521/test
也许用ip地址代替？

标签： java jdbc oracle12c

【解决方案1】：

更多的是网络问题，请检查您的服务器配置并确保它在开发和生产环境中侦听正确的主机和端口。

未知主机错误表明它无法将地址解析为正确的机器 IP。如果您可以使用 IP 地址，它将停止解析主机并减少每个连接请求的解析延迟。

机会是，您的 DNS 服务器无法跟上发出的请求并且无法响应。解决此问题的最佳方法是对主机使用静态内部 IP 地址并直接使用它们。或者微调服务器，以便它们可以处理请求并发。

编辑：

第二个异常表明您的数据库服务器拒绝登录凭据，或者登录过程失败。因此抛出身份验证失败异常。

由于您可能遇到网络问题，我建议您检查两台主机之间的网络质量，并确保您的数据包被正确丢弃。

否则，正如错误所暗示的那样，数据库不接受凭据，它可能与具有多个网络接口但服务器仅侦听一个网络接口并拒绝来自所有其他网络接口的连接有关（假设标准生产服务器环境）

【讨论】：

感谢您的宝贵时间。但是重新启动应用程序后它如何再次工作？
检查更新的答案，如果您能提供有关服务器配置的更多见解，那将很有帮助
但是如果数据库端多次尝试失败，我们必须解锁用户，但这里我们只是重新启动了应用程序。
不应该有任何失败的尝试，除非有人或某些应用程序试图以未经授权的方式访问它。这就解释了为什么在用户被锁定时身份验证失败。主要问题是网络出现故障时应用程序无法看到数据库。休息只是假设为什么首先尝试失败。当网络出现故障时，数据库服务器和您的应用程序永远不会连接，除非它试图登录未经授权的网络接口，否则没有机会锁定用户。无论哪种方式，网络都会导致问题。