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JAVA: How can I set up a JDBC Connection Globally so the connection can be used from anywhere in the program?

Posted on 2007-11-17
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Last Modified: 2013-12-14
Well I'm kinda new to Java. I have some background from college but not advances like the code I'm trying to write.

I am making a Java Application that connects to a Oracle 9i Database.
I started off by creating a login page. Which then I create a object to that method in another Class in another Java file which establish the connection to the database to determine if the connection can be established. But I'd like to make it in a way that I can use the JDBC built in functions like closing the db connection, sending sql using that same connection, getting results using that open connection, without having to create multiple connections and establish one every time. I expect to have other java classes that will use this connection to bring results back into a JTable and even a JTree.

I don't think this information would be helpful, but I am using Netbeans 5.5.1 and Java 1.6.0.03
/*
 * login.java
 *
 * Created on November 15, 2007, 10:25 PM
 */
 
package com.user;
import com.app.db.*;
import java.awt.Color;
import java.awt.LayoutManager;
import oracle.jdbc.util.Login;
/**
 *
 * @author  
 */
public class login extends javax.swing.JFrame {
private static final long serialVersionUID = -3088001842L;
 
    /** Creates new form login */
    public login() {
        initComponents();
        failedpassword.setVisible(false);
        failedusername.setVisible(false);
    }
    
    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    // <editor-fold defaultstate="collapsed" desc=" Generated Code ">                          
    private void initComponents() {
        usernamelb = new javax.swing.JLabel();
        passwordlb = new javax.swing.JLabel();
        serverlb = new javax.swing.JLabel();
        usernametxt = new javax.swing.JTextField();
        passwordtxt = new javax.swing.JPasswordField();
        serverName = new javax.swing.JComboBox();
        loginbtn = new javax.swing.JButton();
        exitbtn = new javax.swing.JButton();
        failedusername = new javax.swing.JLabel();
        failedpassword = new javax.swing.JLabel();
        jSeparator1 = new javax.swing.JSeparator();
 
        setTitle("ILog Login");
        setLocationByPlatform(true);
        setResizable(false);
        usernamelb.setText("Username:");
 
        passwordlb.setText("Password:");
 
        serverlb.setText("Server:");
 
        passwordtxt.setColumns(10);
 
        serverName.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "ILOG" }));
 
        loginbtn.setText("Login");
        loginbtn.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                loginbtnActionPerformed(evt);
            }
        });
 
        exitbtn.setText("Exit");
        exitbtn.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                exitbtnActionPerformed(evt);
            }
        });
 
        failedusername.setFont(new java.awt.Font("Tahoma", 0, 12));
        failedusername.setForeground(java.awt.Color.red);
        failedusername.setText("*");
 
        failedpassword.setFont(new java.awt.Font("Tahoma", 0, 12));
        failedpassword.setForeground(java.awt.Color.red);
        failedpassword.setText("*");
 
        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(76, 76, 76)
                .addComponent(loginbtn)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(exitbtn)
                .addContainerGap(86, Short.MAX_VALUE))
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jSeparator1, javax.swing.GroupLayout.DEFAULT_SIZE, 270, Short.MAX_VALUE))
            .addGroup(layout.createSequentialGroup()
                .addGap(43, 43, 43)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(usernamelb)
                    .addComponent(passwordlb)
                    .addComponent(serverlb))
                .addGap(12, 12, 12)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                    .addComponent(serverName, javax.swing.GroupLayout.Alignment.TRAILING, 0, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addComponent(usernametxt, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.PREFERRED_SIZE, 111, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(passwordtxt, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.PREFERRED_SIZE, 112, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(failedpassword)
                    .addComponent(failedusername))
                .addContainerGap(50, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap(25, Short.MAX_VALUE)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(usernamelb)
                    .addComponent(usernametxt, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(failedusername))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(passwordlb)
                    .addComponent(passwordtxt, javax.swing.GroupLayout.PREFERRED_SIZE, 20, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(failedpassword))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(serverName, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(serverlb))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jSeparator1, javax.swing.GroupLayout.PREFERRED_SIZE, 10, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(loginbtn)
                    .addComponent(exitbtn))
                .addContainerGap())
        );
        pack();
    }// </editor-fold>                        
 
    private void loginbtnActionPerformed(java.awt.event.ActionEvent evt) {                                         
        failedpassword.setVisible(false);
        failedusername.setVisible(false);
        
        usernamelb.setForeground(Color.BLACK);
        passwordlb.setForeground(Color.BLACK);
        
        String v_username = usernametxt.getText();
        char[] Getpassword = passwordtxt.getPassword();
        String v_password = convertPassword(Getpassword);
        
        if ( ( v_username.length() == 0 ) || ( v_username.contains(" ") ) ) {
            failedusername.setVisible(true);
            usernamelb.setForeground(Color.RED);
            if ( ( v_password.length() == 0 ) || ( v_password.contains(" ") ) ) {
                failedpassword.setVisible(true);
                passwordlb.setForeground(Color.RED);
            }
        } else if ( ( v_password.length() == 0 ) || ( v_password.contains(" ") ) ) {
            failedpassword.setVisible(true);
            passwordlb.setForeground(Color.RED);
            if ( (counter >= 3) ){
                System.exit(0);   
            }
                counter = counter + 1;
        } else {
            dbConnect run = new dbConnect();
            // String v_servername = (String) serverName.getSelectedItem();
            int v_servername = serverName.getSelectedIndex();
            run.startConnect(v_username, v_password, v_servername);
        }
    }                                        
    
    private void exitbtnActionPerformed(java.awt.event.ActionEvent evt) {                                        
        System.exit(0);
    }                                       
    
    
    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() { public void run() { new login().setVisible(true); } } );        
    }
    
     public static String convertPassword(char[] userPassword) {
        // Declare variables
        String strRet = new String("");
            // Go through each character
            for (int i = 0; i < userPassword.length; i++)
            {
                strRet += userPassword[i];
            }
        return strRet;
    }
    
    // Variables declaration - do not modify                     
    private javax.swing.JButton exitbtn;
    private javax.swing.JLabel failedpassword;
    private javax.swing.JLabel failedusername;
    private javax.swing.JSeparator jSeparator1;
    private javax.swing.JButton loginbtn;
    private javax.swing.JLabel passwordlb;
    private javax.swing.JPasswordField passwordtxt;
    private javax.swing.JComboBox serverName;
    private javax.swing.JLabel serverlb;
    private javax.swing.JLabel usernamelb;
    private javax.swing.JTextField usernametxt;
    // End of variables declaration                   
    int counter = 0;
}
 
 
 
/*
 * dbConnect.java
 *
 * Created on November 16, 2007, 3:33 PM
 *
 * @author cj58096
 */
 
package com.app.db;
import java.io.*;
import java.text.*;
import java.sql.*;
import javax.swing.JOptionPane;
 
public class dbConnect {
    /** Creates a new instance of dbConnect */    
    public void startConnect(String loginUsername, String loginPassword, int v_serverno ) {
 
            String serverName = null;
            String server = null;
 
            String sResult = "Worked";
            Connection connection = null;            
            
            switch ( v_serverno ){
                case 0: serverName = " "; server = "P"; break;
                case 1: serverName = " "; server = "IM"; break; 
                case 2: serverName = " "; server = "OS"; break; 
                case 3: serverName = " "; server = "Q"; break; 
                case 4: serverName = " "; server = "IMQ"; break; 
                case 5: serverName = " "; server = "OSQ"; break; 
                case 6: serverName = " "; server = "T"; break; 
                case 7: serverName = " "; server = "IT"; break; 
                case 8: serverName = " "; server = "OT"; break; 
                case 9: serverName = "192.168.1.4"; server = "World"; break;
            }
    try
            {
            // Load the JDBC driver
              String driverName = "oracle.jdbc.driver.OracleDriver";
              Class.forName(driverName);
              DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
 
            // Create a connection to the database
              String portNumber = "1521";
              String url = "jdbc:oracle:thin:@" + serverName + ":" + portNumber + ":" + server;
              connection = DriverManager.getConnection(url, loginUsername, loginPassword);
              
          }
            catch (ClassNotFoundException e)
            {
                sResult = "Could Not Find The Database Driver";
          }
            catch (SQLException e)
            {
                sResult = "Could Not Connect To The Database";
          }
            JOptionPane.showMessageDialog(null, sResult, "Server: " + server, JOptionPane.INFORMATION_MESSAGE);
            //System.exit(0);
    }
    
}

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Question by:ramanjitsingh04
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4 Comments
 
LVL 17

Expert Comment

by:contactkarthi
ID: 20306017
if you just want to use one single instance of a connection there is a design pattern called as singleton you can try that
http://forums.devx.com/showthread.php?t=157251

discussion on the topic related to your question

http://forum.java.sun.com/thread.jspa?threadID=5227022&messageID=9924745

or have a look at

http://www.developer.com/java/other/article.php/626291
0
 

Author Comment

by:ramanjitsingh04
ID: 20306514
Hey, Thanks for the links. But I can't figure out how to intergrate it to my code. All the examples use static final data, making the classes static. I need the data to be dynamic. As you can see the code itself gets the input from the pull down menu on the login screen and changes the server ip and server name based of it. I rather not use external property files (the ppl using this application, aren't very computer savy). That's why I need everything built into the logic. Could you point me in the direction based of the current code. If you think the current code isn't suitable to handle what I need, please if could suggest what I should do.
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LVL 10

Accepted Solution

by:
adrpo earned 900 total points
ID: 20838189

Well, you could just create the connection like this:
            // String v_servername = (String) serverName.getSelectedItem();
            int v_servername = serverName.getSelectedIndex();
            Connection c = dbConnect.getFirstConnection(v_username, v_password, v_servername, false);
            // use this connection until you want another one.
            // You can just call dbConnect.getExistingConnection() anywhere you need the same connection
             
Cheers,
za-k/
/*
 * dbConnect.java
 *
 * Created on November 16, 2007, 3:33 PM
 *
 * @author cj58096
 */
 
package com.app.db;
import java.io.*;
import java.text.*;
import java.sql.*;
import javax.swing.JOptionPane;
 
public static class dbConnect {
 
    static Connection connection = null;    
 
    /** Creates a new instance of dbConnect */    
    public static Connection getFirstConnection(String loginUsername, String loginPassword, int v_serverno) {
            
            // we want a new connection?
            if (connection != null)
            {
               connection.close();  // close the connection we have
               connection = null;
            }               
            // we need to make a connection.
            static String serverName = null;
            static String server = null;
 
            static String sResult = "Worked";            
            
            switch ( v_serverno ){
                case 0: serverName = " "; server = "P"; break;
                case 1: serverName = " "; server = "IM"; break; 
                case 2: serverName = " "; server = "OS"; break; 
                case 3: serverName = " "; server = "Q"; break; 
                case 4: serverName = " "; server = "IMQ"; break; 
                case 5: serverName = " "; server = "OSQ"; break; 
                case 6: serverName = " "; server = "T"; break; 
                case 7: serverName = " "; server = "IT"; break; 
                case 8: serverName = " "; server = "OT"; break; 
                case 9: serverName = "192.168.1.4"; server = "World"; break;
            }
    try
            {
            // Load the JDBC driver
              String driverName = "oracle.jdbc.driver.OracleDriver";
              Class.forName(driverName);
              DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
 
            // Create a connection to the database
              String portNumber = "1521";
              String url = "jdbc:oracle:thin:@" + serverName + ":" + portNumber + ":" + server;
              connection = DriverManager.getConnection(url, loginUsername, loginPassword);
          }
            catch (ClassNotFoundException e)
            {
                sResult = "Could Not Find The Database Driver";
                connection = null;
          }
            catch (SQLException e)
            {
                sResult = "Could Not Connect To The Database";
                connection = null;
          } 
          JOptionPane.showMessageDialog(null, sResult, "Server: " + server, JOptionPane.INFORMATION_MESSAGE);
          return connection;
    }
 
    public static Connection getExistingConnection()
    {
        return connection;
    }
}

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LVL 10

Assisted Solution

by:adrpo
adrpo earned 900 total points
ID: 20838213
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