dbmanager.java

来自「用java编写的数据库管理程序」· Java 代码 · 共 132 行

package createdb;

import java.awt.*;
import java.awt.event.*;
import java.util.Vector;
import javax.swing.*;
import javax.swing.event.*;

public class DBManager extends JFrame{
  JMenuBar menuBar = new JMenuBar();
  JDesktopPane desktop = new JDesktopPane();
  String database = null;
  String tableName = null;
  String menuSelection = null;
  TableBuilderFrame tableMaker = null;
  TableEditFrame tableEditor = null;    // added for Chapter 6
  DatabaseUtilities dbUtils = null;

  TableMenu tableMenu = new TableMenu();
  EditMenu editMenu = new EditMenu();   // added for Chapter 6

  MenuListener menuListener = new MenuListener();

  public DBManager(){
    setJMenuBar(menuBar);
    setTitle("JDBC Database Bible");
    getContentPane().setLayout(new BorderLayout());
    getContentPane().add(desktop,BorderLayout.CENTER);
    setSize(new Dimension(640,480));
    setLocation(100,100);

    menuBar.add(tableMenu);
    tableMenu.setMenuListener(menuListener);

    menuBar.add(editMenu);                    // added for Chapter 6
    editMenu.setMenuListener(menuListener);

    setVisible(true);
  }

  private void displayTableBuilderFrame(){
    tableName = JOptionPane.showInputDialog(this,"Table:",
                "Select table",JOptionPane.QUESTION_MESSAGE);
    if(tableName==null)
      return;
    tableMaker = new TableBuilderFrame(tableName);
    tableMaker.setCommandListener(new CommandListener());
    desktop.add(tableMaker);
    tableMaker.setVisible(true);
  }

  private void displayTableEditFrame(){  // added for Chapter 6
    tableName = JOptionPane.showInputDialog(this,"Table:",
                "Select table",JOptionPane.QUESTION_MESSAGE);
    if(tableName==null)
      return;
    tableEditor = new TableEditFrame(tableName,dbUtils);
    desktop.add(tableEditor);
    tableEditor.setVisible(true);
  }

  private void selectDatabase(){
    database = JOptionPane.showInputDialog(this,
               "Database:","Select database",
               JOptionPane.QUESTION_MESSAGE);
    dbUtils = new DatabaseUtilities();
    dbUtils.setDatabaseName(database);
    dbUtils.setExceptionListener(new ExceptionListener());

    tableMenu.enableMenuItem("New Table",true);
    tableMenu.enableMenuItem("Drop Table",true);

    editMenu.enableMenuItem("Insert",true);
    editMenu.enableMenuItem("Update",true);
    editMenu.enableMenuItem("Delete",true);
  }

  private void executeSQLCommand(String SQLCommand){
    dbUtils.execute(SQLCommand);
  }

  private void dropTable(){
    tableName = JOptionPane.showInputDialog(this,"Table:",
                "Select table",JOptionPane.QUESTION_MESSAGE);
    if(tableName==null)
      return;
                  int option = JOptionPane.showConfirmDialog(null,
                                    "Dropping table "+tableName,
                                    "Database "+database,
                                    JOptionPane.OK_CANCEL_OPTION);
                  if(option==0){
      executeSQLCommand("DROP TABLE "+tableName);
    }
  }

  class MenuListener implements ActionListener{
    public void actionPerformed(ActionEvent event){
      String menuSelection = event.getActionCommand();
      if(menuSelection.equals("Database")){
        selectDatabase();
      }else if(menuSelection.equals("New Table")){
        displayTableBuilderFrame();
      }else if(menuSelection.equals("Drop Table")){
        dropTable();
      }else if(menuSelection.equals("Insert")){
        displayTableEditFrame();
      }else if(menuSelection.equals("Exit")){
        System.exit(0);
      }
    }
  }

  class ExceptionListener implements ActionListener{
    public void actionPerformed(ActionEvent event){
      String exception = event.getActionCommand();
      JOptionPane.showMessageDialog(null, exception,
                            "SQL Error", JOptionPane.ERROR_MESSAGE);
    }
  }

  class CommandListener implements ActionListener{
    public void actionPerformed(ActionEvent event){
      String SQLCommand = event.getActionCommand();
      executeSQLCommand(SQLCommand);
          }
  }

  public static void main(String args[]){
    DBManager dbm = new DBManager();
  }
}