jdbcdemo2.java

java程序设计语言源代码

//Example 2 of Chapter 10

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

public class JDBCDemo2 extends JFrame
{
	private ScrollPane scrollPane;
	private JTextArea area;
	private String driver = "com.mysql.jdbc.Driver";
	private String url = "jdbc:mysql://localhost:3306/graduation_design";
	private String user = "root";
	private String password = "";
	private Connection connect;
	private Statement stmt;
	private ResultSet results;
	
	public JDBCDemo2()
	{
		super( "JDBC查询演示" );
		
		getContentPane().setLayout( new BorderLayout() );
		scrollPane = new ScrollPane();
		area = new JTextArea();
		area.setEditable( false );
		scrollPane.add( area );
		getContentPane().add( scrollPane, BorderLayout.CENTER );
		
		try{
			//载入JDBC驱动程序
			Class.forName( driver );
			//连接到数据库
			Connection connect = DriverManager. getConnection( url, user, password );
			//创建Statement对象
			stmt = connect.createStatement();
			//获取查询结果
			String query = "SELECT * FROM namelist";
			results = stmt.executeQuery( query );
			//处理查询结果
			StringBuffer s = new StringBuffer();
			//获取数据描述信息
			ResultSetMetaData metaData = results.getMetaData();
			int columns = metaData.getColumnCount();
			//输出数据表列名
			for ( int i = 1; i <= columns; i++ )
				s.append( metaData.getColumnName( i ) + "    " );
			s.append( "\n" );
			//输出数据记录
			while ( results.next() )
			{
				for ( int i = 1; i <= columns; i++ )
					s.append( "   " + results.getObject( i ) );
				s.append( "\n" );
			}
			area.append( s.toString() );
		}
		catch ( SQLException sqlException )
		{
			area.append( "发生SQLException异常\n" );
		}
		catch ( ClassNotFoundException classNotFound )
		{
			area.append( "发生ClassNotFoundException异常\n" );
		}
		finally{
			try{
				results.close();
				stmt.close();
				connect.close();
			}
			catch ( SQLException sqlException )
			{
				sqlException.printStackTrace();
			}
			catch ( NullPointerException nullpointerException )
			{
				nullpointerException.printStackTrace();
			}
		}
		setSize( 420, 240 );
		setVisible( true );
	}
	
	public static void main( String args[] )
	{
		JDBCDemo2 window = new JDBCDemo2();
		window.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
	}
}