Conecte java com mysql no servidor ubuntu

Question

Estou tentando conectar meu aplicativo Java ao MySql executado em um servidor Ubuntu 14.04 instalado no Virtual Box na mesma máquina que meu aplicativo. Eu instalei o mysql-server, mysql-client e libmysql-java no ubuntu e executando sql queries dentro do servidor ubuntu parece funcionar bem. Minha aplicação java é:

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;

public class UploadData {
 // The JDBC Connector Class.
  private static final String dbClassName = "com.mysql.jdbc.Driver";

  private static final String CONNECTION =
                          "jdbc:mysql://127.0.0.1/demodb";

  public static void main(String[] args) throws
                             ClassNotFoundException,SQLException
  {
    System.out.println(dbClassName);
    // Class.forName(xxx) loads the jdbc classes and
    // creates a drivermanager class factory
    Class.forName(dbClassName);

    // Properties for user and password. Here the user and password are both 'paulr'
    Properties p = new Properties();
    p.put("user","*******");
    p.put("password","******");

    // Now try to connect
    Connection c = DriverManager.getConnection(CONNECTION,p);

    System.out.println("It works !");
    c.close();
    }
}

O erro que recebo é:

Exception in thread "main" 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.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:389)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1038)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:338)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2237)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2270)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2069)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:794)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:44)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:389)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:399)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:325)
at java.sql.DriverManager.getConnection(Unknown Source)
at java.sql.DriverManager.getConnection(Unknown Source)
at server.UploadData.main(UploadData.java:32)

 Caused by: java.net.ConnectException: Connection refused: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:213)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:297)
... 15 more

Qualquer sugestão será mais que útil,

Obrigado

    

Answer 1

A exceção ocorre quando não há serviço mysql em execução ou escutando:

• Inicie o servidor MySQL

• Verifique o número da porta, você usa a porta padrão 3306 em seu código

  private static final String dbClassName = "jdbc:mysql://127.0.0.1:<your_port_number>/demodb";
  

• Use o endereço IP da sua máquina virtual

  private static final String dbClassName = "jdbc:mysql://<host_name_or_ip_address_of_the_database_server>:<your_port_number>/demodb";
  

• Verifique o firewall nas duas máquinas

• Execute ping no host do servidor MySQL para verificar a conexão

• Verifique o bind-address em /etc/mysql/my.cnf

Desde que você faça outra pergunta em seus comentários

  

Exceção no segmento "main" java.sql.SQLException: null, message from   servidor: "Host '192.168.1.7' não tem permissão para se conectar a este MySQL   servidor

aqui está a resposta.

• Verifique as entradas na tabela MySQL mysql.user na coluna Host

  SELECT * FROM mysql.user;