java.net.ConnectException : Connection timed out: connect error connecting to remote database

Question

我目前正在尝试寻找 Android 应用程序后端的替代方案。目前，我使用 php servlet 来查询 Mysql 数据库。数据库(Mysql)托管在我大学的计算机上，因此我无法更改任何配置，因为我不是管理员。我只能编辑我自己的表格。

我正在尝试使用以下代码创建一个 java RESTful 服务器:

public Connection Get_Connection() throws Exception
{
    try
    {
        int lport=31415;
        String rhost="server01.pairg.dimap.ufrn.br";
        String host="server01.pairg.dimap.ufrn.br";
        int rport=2222;
        String user="sumosensei";
        String password="123456";
        String dbuserName = "sumosensei";
        String dbpassword = "123456";
        String url = "jdbc:mysql://server01.pairg.dimap.ufrn.br:2222/pairg_sumosensei_app";

        String driverName="com.mysql.jdbc.Driver";
        Connection conn = null;
        Session session= null;
        java.util.Properties config = new java.util.Properties(); 
        config.put("StrictHostKeyChecking", "no");
        JSch jsch = new JSch();
        session=jsch.getSession(user, host, 22);
        session.setPassword(password);
        session.setConfig(config);
        System.out.println(rhost+":"+rport);
        System.out.println("Port Forwarded");
        session.connect(30000);
        System.out.println("Connected");
        int assinged_port=session.setPortForwardingL(lport, rhost, rport);
        System.out.println(assinged_port+" -> "+rhost+":"+rport);
        System.out.println("Port Forwarded");

        //mysql database connectivity
        Class.forName("com.mysql.jdbc.Driver");
        conn = DriverManager.getConnection(url, dbuserName, dbpassword);
        System.out.println ("Database connection established");
        System.out.println("DONE");
        /*System.out.println("estabelecendo conexão com o BD...");
        String connectionURL = "jdbc:mysql://server01.pairg.dimap.ufrn.br:2222/pairg_sumosensei_app";
        Connection connection = null;
        Class.forName("com.mysql.jdbc.Driver").newInstance();
        connection = DriverManager.getConnection(connectionURL, "sumosensei", "123456");
        System.out.println("estabelecida conexão com o BD!");*/
        return conn;
    }
    catch (SQLException e)
    {
        e.printStackTrace();
        throw e;    
    }
    catch (Exception e)
    {
        e.printStackTrace();
        throw e;    
    }


}

这段代码给了我这个错误:

com.jcraft.jsch.JSchException: java.net.ConnectException: Connection timed out: connect at com.jcraft.jsch.Util.createSocket(Util.java:386) at com.jcraft.jsch.Session.connect(Session.java:182) at dao.Database.Get_Connection(Database.java:37) at model.ProjectManager.GetKanjisTreinar(ProjectManager.java:34) at webService.FeedService.kanji(FeedService.java:53) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$TypeOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:156) at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:67) at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:163) at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:111) at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:71) at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:111) at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:63) at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:654) at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:612) at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:603) at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:309) at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:425) at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:590) at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:462) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:395) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:250) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:166) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) at java.lang.Thread.run(Thread.java:722) com.jcraft.jsch.JSchException: java.net.ConnectException: Connection timed out: connect at com.jcraft.jsch.Util.createSocket(Util.java:386) at com.jcraft.jsch.Session.connect(Session.java:182) at dao.Database.Get_Connection(Database.java:37) at model.ProjectManager.GetKanjisTreinar(ProjectManager.java:34) at webService.FeedService.kanji(FeedService.java:53) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$TypeOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:156) at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:67) at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:163) at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:111) at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:71) at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:111) at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:63) at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:654) at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:612) at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:603) at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:309) at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:425) at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:590) at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:462) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:395) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:250) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:166) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) at java.lang.Thread.run(Thread.java:722) erro: conexão é nula error

Answer 1

尝试从托管 PHP servlet 的系统 ping 数据库 IP，您似乎没有与目标系统的连接。其次检查 telnet 端口以检查是否可以在 mysql 端口上连接到目标系统。希望这会有所帮助。