如何关闭断开的 jdbc 连接？

Question

I am setting up a connection between two servers (One running a jdbc application and second running an oracle DB) using jdbc to query few tables.

Since these servers reside in two different countries, sometimes there is a disconnect between the two servers.

When the connection is not established due to IO Error: Network adapter could not establish the connection , the app can retry-establish the connection. But once a conn is established, and then there is a disconnect, the application just hangs and doesn't Timeout or come out of the connection.

Can anybody please help me out to close or exit such connections?

Answer 1

Use the try-with-resources statement

String user = "user";
String password = "password";
String url = "jdbc:mysql://localhost:3306/database_name";
try (Connection connect = DriverManager.getConnection(url, user, password);
Statement stmt = connect.createStatement();
ResultSet rs = stmt.executeQuery("SELECT * FROM table;");
) {
    while (rs.next()) {
        // TODO
    }
} catch (Exception e) {
    System.out.println(e);
}

Answer 2

You can handle this in the finally block to ensure that the connection is closed in case of both success and exception. Example code is shared below for your reference.

import java.sql.*;  
class MysqlConnectionExample{  
    public static void main(String args[]){  
        String jdbcUrl = "jdbc:mysql://localhost:3306/dbName";
        String userName = "userName";
        String password = "password";
        String driverName = "com.mysql.jdbc.Driver";
        Connection con= null;
        Statement stmt = null;
        try{  
            // Create connection
            Class.forName(driverName);  
            con = DriverManager.getConnection(jdbcUrl, userName, password);  
            stmt = con.createStatement();  
            ResultSet rs = stmt.executeQuery("SELECT * FROM employee");  

            // Iterate over the results
            while(rs.next()) { 
                System.out.println(rs.getInt(1)+"  "+rs.getString(2)+"  "+rs.getString(3));  
            }
        }
        catch(Exception e){ 
            System.out.println(e);
        }  
        finally{
            // Close connection
            con.close();
        }
    }  
}

Answer 3

if you use connection fool, i think it's will be like youre situation. As other answers, i recommend to use 'connection.close()'; and it needed, it's better to add 'trasation' scope.