paraqueryframe.java~25~

java 数据库编程源代码

//package paraquery;
//import com.borland.jbcl.layout.*;
import java.awt.*;
import java.awt.event.*;
import java.sql.*;
import javax.swing.*;
import javax.swing.UIManager;


/**
   * Title:				使用参数查询数据库程序
   * Description:			教学示范
   * Copyright:				Copyright (c) 2003
   * Company:				北京师范大学计算机系
   * @author				孙一林
   * @version				1.0
   */

public class ParaQueryFrame extends JFrame {
    private JPanel contentPane;
    private FlowLayout xYLayout1 = new FlowLayout(); // 创建显示信息用的组件
    private Label label1 = new Label();
    private TextField numberField = new TextField();
    private Button queryButton = new Button();

    Connection connection = null; // 定义与数据库进行连接的Connection对象
    ResultSet rSet = null; // 定义数据库查询的结果集
    Statement statement = null; // 定义查询数据库的Statement对象

    public ParaQueryFrame() {
      enableEvents(AWTEvent.WINDOW_EVENT_MASK);
      try {
        jbInit();
      }
      catch (Exception e) {
        e.printStackTrace();
      }
    }

    private void jbInit() throws Exception {
      contentPane = (JPanel)this.getContentPane();
      // 初始化组件
      label1.setText("查询学号");
      contentPane.setLayout(xYLayout1);
      this.setSize(new Dimension(400, 300));
      this.setTitle("使用参数查询数据库");
      queryButton.setLabel("查询");
      queryButton.addActionListener(new java.awt.event.ActionListener() { // 设置queryButton按钮监听器
        public void actionPerformed(ActionEvent e) {
          queryButton_actionPerformed(e);
        }
      });
      contentPane.add(label1);
      contentPane.add(numberField);
      contentPane.add(queryButton);
    }

    protected void processWindowEvent(WindowEvent e) {
      super.processWindowEvent(e);
      if (e.getID() == WindowEvent.WINDOW_CLOSING) {
        System.exit(0);
      }
    }

    void queryButton_actionPerformed(ActionEvent e) { // 处理queryButton的ActionEvent
      try {
        Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); // 实例化JDBC-ODBC桥的驱动
        String url = "jdbc:odbc://localhost/d:/java数据库/student"; // 设置连接字符串
        connection = DriverManager.getConnection(url,"xiao","1978"); // 连接数据库
        // 创建Statement接口对象
        statement = connection.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,
                                               ResultSet.CONCUR_UPDATABLE);
        String sql = "select * from studentbase where 学号=" +
            Integer.parseInt(numberField.getText());
        rSet = statement.executeQuery(sql); // 执行学号为输入学号的查询语句
        if (rSet.next() == false) { // 判断数据库中是否有要查询学号的记录，如没有则输出提示框
          JOptionPane msg = new JOptionPane();
          JOptionPane.showMessageDialog(ParaQueryFrame.this, "数据库中没有您查询的学号",
                                        "数据库中没有您查询的学号！", 1);
        }
        else {
          rSet.previous(); // 使指针返回到ResultSet对象的开始
          ResultSetMetaData data = rSet.getMetaData(); // 定义ResultSetMetaData对象data
          numberField.setText(""); // 清空学号文本框
          int col = data.getColumnCount(); // 获取列数
          for (int i = 1; i <= col; i++) { // 打印列名
            if (i < col) {
              System.out.print(data.getColumnName(i) + "  ");
            }
            else {
              System.out.println(data.getColumnName(i));
            }
          }
          while (rSet.next()) { // 打印数据
            for (int i = 1; i <= col; i++) {
              if (i < col) {
                System.out.print(rSet.getString(i) + "  ");
              }
              else {
                System.out.println(rSet.getString(i));
              }
            }
          }
          rSet.close(); // 关闭结果集
        }
      }
      catch (SQLException ex) { // 捕捉异常
        System.out.println("\nERROR:----- SQLException -----\n");
        while (ex != null) {
          System.out.println("Message:   " + ex.getMessage());
          System.out.println("SQLState:  " + ex.getSQLState());
          System.out.println("ErrorCode: " + ex.getErrorCode());
          ex = ex.getNextException();
        }
      }
      catch (Exception ex) {
        ex.printStackTrace();
      }
      finally {
        try {
          if (statement != null) {
            statement.close(); // 关闭Statement接口实例
          }
          if (connection != null) {
            connection.close(); // 关闭Connection接口实例
          }
        }
        catch (SQLException ex) {
          System.out.println("\nERROR:----- SQLException -----\n");
          System.out.println("Message:   " + ex.getMessage());
          System.out.println("SQLState:  " + ex.getSQLState());
          System.out.println("ErrorCode: " + ex.getErrorCode());
        }
      }
    }


    public static void main(String[] args) {
    try {
      UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
    }
    catch(Exception e) {
      e.printStackTrace();
    }

 // private boolean packFrame = false;
   ParaQueryFrame frame = new ParaQueryFrame();
   /* if (packFrame) {
      frame.pack();
    }
    else {
      frame.validate();
    }*/
    Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
    Dimension frameSize = frame.getSize();
    if (frameSize.height > screenSize.height) {
      frameSize.height = screenSize.height;
    }
    if (frameSize.width > screenSize.width) {
      frameSize.width = screenSize.width;
    }
    frame.setLocation((screenSize.width - frameSize.width) / 2, (screenSize.height - frameSize.height) / 2);
    frame.setVisible(true);
  }



  }