Échec de la connexion JDBC: java.sql.SQLException: Échec de la liaison de communication: Mauvaise prise de contact

Question

Je suis un novice de JDBC. Je viens de rencontrer une SQLException pendant que j'essayais de connecter mon programme Java avec la base de données Mysql.

S'il vous plaît trouver les détails de l'erreur de temps d'exécution ci-dessous:

Exception in thread "main" java.sql.SQLException: Communication link failure: Bad handshake 
    at com.mysql.jdbc.MysqlIO.init(Unknown Source) 
    at com.mysql.jdbc.Connection.connectionInit(Unknown Source) 
    at com.mysql.jdbc.jdbc2.Connection.connectionInit(Unknown Source) 
    at com.mysql.jdbc.Driver.connect(Unknown Source) 
    at java.sql.DriverManager.getConnection(DriverManager.java:664) 
    at java.sql.DriverManager.getConnection(DriverManager.java:247) 
    at databaseexample.DatabaseExample.connect(DatabaseExample.java:40) 
    at databaseexample.DatabaseExample.main(DatabaseExample.java:26) 
/home/sreejith/.cache/netbeans/8.2/executor-snippets/run.xml:53: Java returned: 1 

Program Details : 
package databaseexample; 
import java.sql.* 

;

public class DatabaseExample { 

    static boolean flag = false; 
    static String DBURL = "jdbc:mysql://localhost:3306/testdb"; 


    static String CHECK_SQL_QUERY = "SELECT 1"; 
    /** 
    * @param args the command line arguments 
    */ 
    public static void main(String[] args) throws SQLException, ClassNotFoundException { 
     // TODO code application logic here 
     Class.forName("com.mysql.jdbc.Driver"); 
     flag = connect(); 
     if(flag == true) 
     { 
      System.out.println("Connnected !"); 
     } else 
     { 
      System.out.println("not connected."); 
     } 



    } 

    public static boolean connect() throws SQLException { 
     Connection conn = DriverManager.getConnection(DBURL,"root","root"); 

     return true; 
    } 

} 

J'ai essayé de port telnet 3306 et a reçu un résultat comme ci-dessous:

sreejith@desktop:~$ telnet localhost 3306 
Trying 127.0.0.1... 
Connected to localhost. 
Escape character is '^]'. 
[ 
5.7.19-0ubuntu0.16.04.1*4` `iw2)Ml,L* 
             Lmysql_native_password 

!#08S01Got packets out of orderConnection closed by foreign host. 

Je suis en cours d'exécution sur ubuntu 16.04 par la voie. Merci à l'avance :)

Answer 1

Essayez de cette façon:

import java.sql.DriverManager; 
import java.sql.SQLException; 

public class Connection 
{ 
    private static java.sql.Connection connection; 

    public Connection(String serverAddress, String database, String user, String pass) throws ClassNotFoundException, SQLException 
    { 
     Class.forName("com.mysql.jdbc.Driver"); 
     String url = "jdbc:mysql://" + serverAddress + ":3306/" + database; 
     connection = DriverManager.getConnection(url, user, pass); 
    } 

    public java.sql.Connection getConnection() 
    { 
     return connection; 
    } 
}