修改这段代码实现查询 JButton b4 = new JButton("查询"); b4.setPreferredSize(new Dimension(150,30)); b4.addActionListener(new AbstractAction() { @Override public void actionPerformed(ActionEvent e) { String id = t0.getText(); Connection con = DBUtil.getConnect(); String sql = "SELECT * FROM tushu WHERE id = ?"; try { PreparedStatement ps = con.prepareStatement(sql); ps.setString(1,id); int result = ps.executeUpdate(); if (result>0){ JOptionPane.showMessageDialog(QueryDialog.this,"删除成功"); // new StudentFrame(); dataChangelisenter.dataChange(); dispose(); }else { JOptionPane.showMessageDialog(QueryDialog.this,"删除失败"); } } catch (SQLException throwables) { throwables.printStackTrace(); } } });

这段代码是一个查询按钮的实现，但是其中的代码实现的是删除数据，需要进行修改才能实现查询功能。下面是修改后的代码：

JButton b4 = new JButton("查询");
b4.setPreferredSize(new Dimension(150, 30));
b4.addActionListener(new AbstractAction() {
    @Override
    public void actionPerformed(ActionEvent e) {
        String id = t0.getText();
        Connection con = DBUtil.getConnect();
        String sql = "SELECT * FROM tushu WHERE id = ?";
        try {
            PreparedStatement ps = con.prepareStatement(sql);
            ps.setString(1, id);
            ResultSet rs = ps.executeQuery();
            if (rs.next()) {
                String name = rs.getString("name");
                String author = rs.getString("author");
                String publish = rs.getString("publish");
                String price = rs.getString("price");
                JOptionPane.showMessageDialog(QueryDialog.this, "查询成功\n书名：" + name + "\n作者：" + author + "\n出版社：" + publish + "\n价格：" + price);
            } else {
                JOptionPane.showMessageDialog(QueryDialog.this, "查询失败，未找到该书籍");
            }
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
    }
});

修改后的代码中，首先获取用户输入的书籍ID，然后通过PreparedStatement对象执行查询语句，将结果保存到ResultSet对象中。如果ResultSet对象中有数据，则将数据取出并弹出提示框显示，否则提示未找到该书籍。