catchsqlexceptionframe.java

JAVA数据库编程实例随书源码 JAVA数据库编程实例随书源码

package catchsqlexception;

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

/**
 * Title:			捕捉数据库访问异常
 * 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 catchSQLExceptionFrame extends JFrame {
  private JPanel contentPane;
  private TextField tableField = new TextField();
  private Label label1 = new Label();
  private Label label2 = new Label();
  private TextArea exceptionArea = new TextArea();
  private Button queryButton = new Button();

  Connection connection = null;                //定义与数据库进行连接的Connection对象
  ResultSet rs = 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 catchSQLExceptionFrame() {
    enableEvents(AWTEvent.WINDOW_EVENT_MASK);
    try {
      jbInit();
    }
    catch(Exception e) {
      e.printStackTrace();
    }
  }

  private void jbInit() throws Exception  {          //初始化用户界面
    contentPane = (JPanel) this.getContentPane();
    tableField.setBounds(new Rectangle(167, 16, 197, 29));
    contentPane.setLayout(null);
    this.setSize(new Dimension(400, 406));
    this.setTitle("数据库异常捕捉");
    label1.setText("请输入数据库表名：");
    label1.setBounds(new Rectangle(45, 18, 114, 26));
    label2.setText("数据库异常情况");
    label2.setBounds(new Rectangle(155, 65, 91, 24));
    exceptionArea.setEditable(false);
    exceptionArea.setBounds(new Rectangle(13, 96, 374, 197));
    queryButton.setLabel("查询");
    queryButton.setBounds(new Rectangle(145, 327, 111, 29));
    queryButton.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(ActionEvent e) {
        queryButton_actionPerformed(e);
      }
    });
    contentPane.add(exceptionArea, null);
    contentPane.add(tableField, null);
    contentPane.add(label1, null);
    contentPane.add(label2, null);
    contentPane.add(queryButton, null);
  }

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

  void queryButton_actionPerformed(ActionEvent e) {   //查询用户指定的数据库，若产生异常则在用户界面中显示
    exceptionArea.setText("");                        //清空异常处理显示框
    try {
      String tableName = tableField.getText();        //获取用户指定的表名
      Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");  //指定与数据库连接使用JDBC-ODBC桥驱动程序
      String url = "jdbc:odbc:student";               //指定数据源名
      connection = DriverManager.getConnection(url);  //与数据源建立连接
      statement = connection.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);  //创建Statement接口实例
      String sql = "select * from " + tableName;      //创建取出用户指定的表中所有数据的SQL语句
      ResultSet rs = statement.executeQuery(sql);     //将数据存入结果集中
      JOptionPane msg = new JOptionPane();
      JOptionPane.showMessageDialog(this, "查询成功", "查询成功！", 1);
    }
    catch(SQLException ex){                           //处理数据库访问异常
      exceptionArea.append("\nERROR:----- SQLException -----\n");
      while (ex != null) {                            //依次显示数据库访问的各条异常
        exceptionArea.append("Message:   " + ex.getMessage() + "\n");    //获取数据库访问异常信息
        exceptionArea.append("SQLState:  " + ex.getSQLState() + "\n");   //获取数据库访问异常状态
        exceptionArea.append("ErrorCode: " + ex.getErrorCode() + "\n");  //获取数据库访问异常代码
        ex = ex.getNextException();                                      //取得下一条访问异常
      }
    }
    catch(Exception ex ) {                           //处理其他异常情况
      exceptionArea.append(ex.toString() + "\n");
    }
    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)  {
        exceptionArea.append("\nERROR:----- SQLException -----\n");
        while (ex != null) {                            //依次显示数据库访问的各条异常
          exceptionArea.append("Message:   " + ex.getMessage() + "\n");    //获取数据库访问异常信息
          exceptionArea.append("SQLState:  " + ex.getSQLState() + "\n");   //获取数据库访问异常状态
          exceptionArea.append("ErrorCode: " + ex.getErrorCode() + "\n");  //获取数据库访问异常代码
          ex = ex.getNextException();                                      //取得下一条访问异常
        }
      }
    }
  }
}