import java.sql.*; import javax.swing.*; import java.awt.*; import java.awt.event.*; import java.util.*; public class SampleIntro extends JFrame { private Connection connection; private Statement statement; private ResultSet resultSet; private ResultSetMetaData rsMetaData; //GUI变量定义private JTable table; private JTextArea inputQuery; private JButton submitQuery; public SampleIntro() { //Form的标题 super( "输入SQL语句，按查询按钮查看结果。" ); String url = "jdbc:mysql://localhost:3306/STOREDB"; String username = "root"; String password = ""; //加载驱动程序以连接数据库try {     Class.forName( "org.gjt.mm.mysql.Driver" );   //com.mysql.jdbc.Driver    connection = DriverManager.getConnection(     url, username, password ); } //捕获加载驱动程序异常catch ( ClassNotFoundException cnfex ) { System.err.println( "装载 JDBC/ODBC 驱动程序失败。" ); cnfex.printStackTrace(); System.exit( 1 ); // terminate program } //捕获连接数据库异常catch ( SQLException sqlex ) { System.err.println( "无法连接数据库" ); sqlex.printStackTrace(); System.exit( 1 ); // terminate program } //如果数据库连接成功，则建立GUI//SQL语句String test="SELECT * FROM CUSTOMERS"; inputQuery = new JTextArea( test, 4, 30 ); submitQuery = new JButton( "查询" ); //Button事件submitQuery.addActionListener( new ActionListener() { public void actionPerformed( ActionEvent e ) { getTable(); } } ); JPanel topPanel = new JPanel(); topPanel.setLayout( new BorderLayout() ); //将"输入查询"编辑框布置到 "CENTER"topPanel.add( new JScrollPane( inputQuery), BorderLayout.CENTER ); //将"提交查询"按钮布置到 "SOUTH"topPanel.add( submitQuery, BorderLayout.SOUTH ); table = new JTable(); Container c = getContentPane(); c.setLayout( new BorderLayout() ); //将"topPanel"编辑框布置到 "NORTH"c.add( topPanel, BorderLayout.NORTH ); //将"table"编辑框布置到 "CENTER"c.add( table, BorderLayout.CENTER ); getTable(); setSize( 500, 300 ); //显示Formshow(); } private void getTable() {     try {     //执行SQL语句    String query = inputQuery.getText();     statement = connection.createStatement();     resultSet = statement.executeQuery( query );     //在表格中显示查询结果    displayResultSet( resultSet );     }     catch ( SQLException sqlex ) {     sqlex.printStackTrace();     } } private void displayResultSet( ResultSet rs ) throws SQLException {     //定位到达第一条记录    boolean moreRecords = rs.next();     //如果没有记录，则提示一条消息    if ( ! moreRecords ) {     JOptionPane.showMessageDialog( this,     "结果集中无记录" );     setTitle( "无记录显示" );     return;     }     Vector columnHeads = new Vector();     Vector rows = new Vector();     try {     //获取字段的名称    ResultSetMetaData rsmd = rs.getMetaData();     for ( int i = 1; i <= rsmd.getColumnCount(); ++i )     columnHeads.addElement( rsmd.getColumnName( i ) );     //获取记录集    do {     rows.addElement( getNextRow( rs, rsmd ) );     } while ( rs.next() );     //在表格中显示查询结果    table = new JTable( rows, columnHeads );     JScrollPane scroller = new JScrollPane( table );     Container c = getContentPane();     c.remove(1);     c.add( scroller, BorderLayout.CENTER );     //刷新Table    c.validate(); } catch ( SQLException sqlex ) { sqlex.printStackTrace(); } } private Vector getNextRow( ResultSet rs, ResultSetMetaData rsmd ) throws SQLException {     Vector currentRow = new Vector();     for ( int i = 1; i <= rsmd.getColumnCount(); ++i )     currentRow.addElement( rs.getString( i ) );     //返回一条记录     return currentRow; } public void shutDown() {     try {     //断开数据库连接    connection.close();     }     catch ( SQLException sqlex ) {     System.err.println( "Unable to disconnect" );     sqlex.printStackTrace(); } } public static void main( String args[] ) { final SampleIntro app = new SampleIntro(); app.addWindowListener( new WindowAdapter() { public void windowClosing( WindowEvent e ) { app.shutDown(); System.exit( 0 ); } } ); } }