javaxml数据查询 java中查询数据库

利用Connection对象的createStatement方法建立Statement对象，利用Statement对象的executeQuery()方法执行SQL查询语句进行查询，返回结果集，再形如getXXX()的方法从结果集中读取数据。经过这样的一系列步骤就能实现对数据库的查询。

【例 13-9】Java应用程序访问数据库。应用程序打开考生信息表ksInfo，从中取出考生的各项信息。设考生信息数据库的结构如下：

类型	字符串	字符串	整数	字符串	字符串
字段名	考号	姓名	成绩	地址	简历

import java.awt.*; 

import java.awt.event.*; 

import javax.swing.*; 

import java.util.*; 

import java.sql.*; 

public class Example10_9 extends JFrame implements ActionListener{ 

    public static Connection connectByJdbcodbc(String url, String username,String password){ 

        Connection con = null; 

        try{ 

            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");  //加载ODBC驱动程序 

        } 

        catch (Exception e){ 

            e.printStackTrace(); 

            return null; //加载失败，连接不成功 

        } 

        try{ 

            con = DriverManager.getConnection(url, username, password); 

        } 

        catch (SQLException e){ 

            e.printStackTrace(); 

            return null; //连接失败 

        } 

        return con; //连接成功 

    } 

    String title[] ={"考号", "姓名", "成绩", "地址", "简历"}; 

    JTextField txtNo = new JTextField(8); 

    JTextField txtName = new JTextField(10); 

    JTextField txtScore = new JTextField(3); 

    JTextField txtAddr = new JTextField(30); 

    JTextArea txtresume = new JTextArea(); 

    JButton prev = new JButton("前一个"); 

    JButton next = new JButton("后一个"); 

    JButton first = new JButton("第一个"); 

    JButton last = new JButton("最后一个"); 

    Statement sql; //SQL语句对象 

    ResultSet rs; //存放查询结果对象 

    Example10_9(Connection connect){ 

        super("考生信息查看窗口"); 

        setSize(450, 350); 

        try{ 

            sql = connect.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY); 

            rs = sql.executeQuery("SELECT * FROM ksInfo"); 

            Container con = getContentPane(); 

            con.setLayout(new BorderLayout(0, 6); JPanel p[] = new JPanel[4]; 

            for (int i = 0; i < 4; i++){ 

                p[i] = new JPane(new FlowLayout(FlowLayout.LEFT, 8, 0)); 

                p[i].add(new JLabel(title[i])); 

            } 

            p[0].add(txtNo); 

            p[1].add(txtName); 

            p[2].add(txtScore); 

            p[3].add(txtAddr); 

            JPanel p1 = new JPane(new GridLayout94, 1, 0, 8)); 

            JScrollPane jsp = new JScrollPane(txtResume, 

                JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, 

                JScrollPane.HORIZONTAL_SCROLLBAR_NEVER); 

                jsp.setPreforredSize(new Dimension(300, 60); 

            for (int i = 0; i < 4; i++){ 

                p1.add(p[i]); 

            } 

            JPanel p2 = new JPanel(new FlowLayout(FlowLayout.LEFT, 10, 0); 

            p2.add(new JLabel(title[4])); 

            p2.add(jsp); 

            Jpanel p3 = new Jpanel(); 

            p3.add(prev); 

            p3.add(next); 

            p3.add(first); 

            p3.add(last); 

            prev.addActionListener(this); 

            next.addActionListener(this); 

            first.addActionListener(this); 

            last.addActionlistener(this); 

            rs.first(); 

            readRecord(); 

        } 

        catch (Exception e){ 

            e.printStackTrace(): 

        } 

        setVisible(ture); 

    } 

    public void modifyRecord(Connection connect){ 

        String stuNo = (String)JOptionPane.showInputDialog(null, 

            "请输入考生考号", "输入考号对话框", JOptionPane.PLAIN_MESSAGE, null, 

            null, ""); 

        try { 

            sql = connect.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY); 

            rs = sql.executeQuery("SELECT * FROM ksInfo"); 

            Container con = getContentPane(); 

            con.setLayout(new Boarderlayout(0, 6)); 

            Jpanel p[] = new JPanel[4]; 

            for (int i = 0; i < ; i++){ 

                p[i] = new JPane(new FlowLayout(flowLayout.LEFT, 8, 0)); 

                p[i].add(new JLabel(title[i])); 

            } 

            p[0].add(txtNo); 

            p[1].add(txtName); 

            p[2].add(txtScore); 

            p[3].add(txtAddr); 

            Jpanel p1 = new Jpane(new GridLayout(4, 1, 0, 8)); 

            JScrollPane jsp = new JScrollPane(txtResume, 

                JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, 

                JScrollPane.HORIZONTAL_SCROLLBAR_NEVER); 

            jsp.setPreferredSize (new dimension(300, 60)); 

            for (int i = 0; i < 4; i++){ 

                p1.add(p[i]); 

            } 

            Jpanel p2 = new JPanel(new FlowLayout(FlowLayout.LEFT, 10, 0)); 

            p2.add(new JLableI(title[4])); 

            p2.add(jsp); 

            JPanel p3 = new JPanel(); 

            p3.add(prev); 

            p3.add(next); 

            p3.add(first); 

            p3.add(last); 

            prev.addActionListener(this); 

            next.addActionListener(this); 

            first.addActionListenerIthis); 

            last.addActionListener(this); 

            rs.first(); 

            readRecord(); 

        } 

        catch (Exception e){ 

            e.printStackTrace(); 

        } 

        setVisible(true); 

    } 

    boolean readRecord(){ 

        try{ 

            txtNo.setText(rs.getString("考号")); txtName.setText(rs.getString("姓名")); txtScore.setText(rs.getString("成绩")); 

            txtAddr.setText(rs.getString("地址")); txtResume.setText(rs.getString("简历")); 

        } 

        catch (SQLException e){ 

            e.printStackTrace(); return false; 

        } 

        return true; 

    } 

    public void actionPerformed(ActionEvent e){ 

        try{ 

            if (e.getSource() == prev)rs.previous(); 

            else if (e.getSource() == next)rs.next(); 

            else if (e.getSource() == first)rs.first(); 

            else if (e.getSource() == last)rs.last(); readRecord(); 

        } 

        catch (Exception e2){} 

    } 

    public static void main(String args[]){ 

        connection connect = null; 

        JFrame .setDefaultLookAndFeeDecorated(true); 

        Font font = new Font("JFrame", Font.PLAIN, 14); 

        if ((connect =connectByJdbcOdbc("jdbc:odbc:redsun", "xia", "1234")) == null){ 

            JOptionPane.showMessageDialog(null, "数据库连接失败!"); 

            System.exit ( - 1); 

        } 

        new Example10_9(connect); //创建对象 

    } 

}