java - JDBC + Swing:无法获取表内容

我正在学习JDBC，这是一个全新的知识。我非常了解MySQL。我的小程序中有一个搜索表单（选项卡2），在其中搜索食物。当我单击搜索时，我希望它从数据库中搜索确切的食物，并仅返回该特定行的表内容。但是我没有任何结果。仅打开一个空框架。但是，当我将查询输入为“ SELECT * FROM table”时，我将获得完整的表。但是我只需要搜索的那一行。谁能告诉我我要去哪里错了？这是我的代码：

    import java.awt.*;
    import java.awt.event.*;
    import java.sql.DriverManager;
    import java.util.Vector;
    import javax.swing.*;
    import com.mysql.jdbc.*;

    public class Tryout extends JFrame  implements ActionListener {

            private static final long serialVersionUID = 1L;

            final Vector columnNames = new Vector();
            final Vector data = new Vector();

            private JTabbedPane tabbedPane = new JTabbedPane();
            private JPanel inputpanel;
            private JPanel searchpanel;
            public String s;

            public Tryout()  {
                    inputpanel = createPage1();
                    searchpanel = createPage2();
                    tabbedPane.addTab("Input Form", inputpanel);
                    tabbedPane.addTab("Search Form", searchpanel);
                    this.add(tabbedPane, BorderLayout.CENTER);
            }

            public JPanel createPage1()  {
                JPanel panel = new JPanel();
                panel.setLayout(new GridBagLayout());
                GridBagConstraints c = new GridBagConstraints();
                //Some code
                return panel;
            }

            public JPanel createPage2() {

                    JPanel panel = new JPanel();
                    panel.setLayout(new GridBagLayout());
                    GridBagConstraints c = new GridBagConstraints();
                    c.anchor = GridBagConstraints.LINE_START;
                    c.weightx = 0.5;
                    c.weighty = 0.5;
                    JLabel region = new JLabel("Enter Region");
                    c.anchor = GridBagConstraints.FIRST_LINE_START;
                    c.gridx = 0;
                    c.gridy = 0;
                    panel.add(region, c);
                    JTextField field = new JTextField(20);
                    c.anchor = GridBagConstraints.FIRST_LINE_START;
                    c.gridx = 1;
                    c.gridy = 0;
                    panel.add(field, c);
                    JButton search = new JButton("SEARCH");
                    c.anchor = GridBagConstraints.FIRST_LINE_START;
                    c.gridx = 2;
                    c.gridy = 0;
                    panel.add(search, c);
                    s = field.getText();
                    search.addActionListener(new ActionListener() {

                        public void actionPerformed(ActionEvent ae){

                        try{
                        Connection con = null;
                        Class.forName("com.mysql.jdbc.Driver");
                        con = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/delikat", "root", "");
                        PreparedStatement statement = (PreparedStatement) con.prepareStatement("SELECT * FROM delicious WHERE name = ?");
statement.setString(1,s);
ResultSet rs= (ResultSet) statement.executeQuery();
                        ResultSetMetaData md = (ResultSetMetaData) rs.getMetaData();
                        int columns = md.getColumnCount();
                        for (int i = 1; i <= columns; i++) {
                        columnNames.addElement( md.getColumnName(i) );
                        }
                        while (rs.next()) {
                        Vector row = new Vector(columns);
                        for (int i = 1; i <= columns; i++) {
                        row.addElement( rs.getObject(i) );
                        }
                        data.addElement( row );
                        }
                        rs.close();
                        statement.close();
                        }
                        catch(Exception e) {}
                        JFrame tab=new JFrame();
                        JTable table = new JTable(data, columnNames);
                        JScrollPane scrollPane = new JScrollPane( table );
                        tab.add( scrollPane );
                        tab.setVisible(true);
                        tab.setSize(300,100);
                        }
                        });
                    return panel;
            }

            public static void main(String args[]) {
                    SwingUtilities.invokeLater(new Runnable() {
                            @Override
                            public void run() {
                                    Tryout ex = new Tryout();
                                    ex.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                                    ex.setSize(500,500);
                                    ex.setVisible(true);
                            }
                    });
            }
    }

这是我的桌子：



另外，我正在尝试在搜索表单下方的面板中显示表格，但添加时却显示错误

panel.add(scrollpane);

我也该如何解决这个问题？

谢谢

最佳答案

基本调试。您是否显示了PreparedStatement中使用的“ s”值？

s = field.getText();

据我所知，该语句是在构建GUI时执行的，这没有任何意义，因为用户甚至没有在此文本字段中输入任何文本。

实际调用SQL时需要执行该语句。