Error connection JDBC

Question

i have problem. When I try to connect to a remote database on the server. I get this exception.

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
at sun.reflect.GeneratedConstructorAccessor27.newInstance(Unknown Source)

I have shortened full stack trace.

I seem to close all the connections. Everything works on the local database, what's the problem? Here is an example of connecting

    public static Connection getConnection()
        throws ClassNotFoundException,
        SQLException {
    Class.forName("com.mysql.jdbc.Driver");
    return DriverManager.getConnection(
            "jdbc:mysql://zrn.mysql.ukraine.com.ua:3306/zrn_program?" +
                    "autoReconnect=true&useSSL=false",
            "USERNAME",
            "PASSWORD");
}

Sample queries

public static List<Training> showTraining(String date){

    List<Training> trainings = new ArrayList<>();

    try (Connection con = Connector.getConnection();
         PreparedStatement pst = con.prepareStatement("SELECT * FROM view_training" +
                 " WHERE training_date = ?")){
        pst.setDate(1, Date.valueOf(date));
        ResultSet rs = pst.executeQuery();
        while (rs.next()){
            trainings.add(new Training(rs.getInt("training_id"),rs.getString("patient"),
                    rs.getString("specialist"),rs.getString("training_date"),
                    rs.getString("training_time"),rs.getBoolean("hasTicket"),
                    rs.getString("category"),rs.getString("status"),rs.getDouble("sum"),
                    rs.getString("color")));
        }
        rs.close();
    } catch (SQLException | ClassNotFoundException e) {
        e.printStackTrace();
    }
    return trainings;
}

Help, please.

UPD1

this full stack trace

om.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
at sun.reflect.GeneratedConstructorAccessor27.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
at com.mysql.jdbc.Util.getInstance(Util.java:408)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:918)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:897)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:886)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:860)
at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2163)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2088)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:806)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.GeneratedConstructorAccessor25.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:410)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:328)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at database.Connector.getConnection(Connector.java:13)
at database.DBTraining.showConsultation(DBTraining.java:268)
at servlet.views.Main.doGet(Main.java:58)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:614)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:956)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:625)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2522)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2511)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)

Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
    at sun.reflect.GeneratedConstructorAccessor26.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
    at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:989)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:341)
    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2251)
    at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2104)
    ... 37 more

Caused by: java.net.ConnectException: Connection timed out: connect
        at java.net.DualStackPlainSocketImpl.connect0(Native Method)
        at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)
        at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:345)
        at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
        at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
        at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
        at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
        at java.net.Socket.connect(Socket.java:589)
        at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:211)
        at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:300)
        ... 39 more

Make sure that your database server is up in the specified url. — Sudhakar, May 31 '17 at 12:24
You can check this link - https://stackoverflow.com/questions/38848000/java-mysql-connect-to-server/38848473#38848473 This may help you. — Sudip, May 31 '17 at 13:09

score 0 · Answer 1 · answered May 31 '17 at 12:23

0

It looks like your remote database is not visible for remote access, so your program cannot connect to your database server (compare this question).

You should check you are able to connect with the mysql command line client, to your remote database.

answered May 31 '17 at 12:23

Simulant

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I can connect, it works, and then it crashes. – ImZ May 31 '17 at 12:25

Error connection JDBC

1 Answers1