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I am currently trying to find an alternative to my android application backend. Currently, I use php servlets to query the Mysql database. The database(Mysql) is hosted on a computer of my college, so I cannot change any configurations because I am not the administer. I can only edit my own tables.

I am trying to create a java RESTful server using this code:

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;    
    }


}

This code is giving me this error:

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

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try to ping the DB IP from your system hosting PHP servlet, it seems you dont have connectivity to the destination system. Second check telnet port to check if you can connect to destination system on mysql port. Hope this helps.

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3 Comments

tried using telnet and It seems the 2222 port is open on server01.pairg.dimap.ufrn.br, so I think this is not the problem. Will try the ping thing later, but thanks for the support
tried to ping to server01.pairg.dimap.ufrn.br, but the 4 solicitations were lost, exceding time limit. What does this mean?
if ping is failed that means you don't have connectivity to the server. There is no communication link between two machines through which they can communicate. you need to contact network admin of your college and ask him to allow your IP or give you access to connect with system.

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