标签：java jdbc swing jtable abstracttablemodel

我正在为数据库制作一个GUI项目,有两个类用于GUI.连接器类用于连接用户凭据.如果凭据正确,则获取AbstractTableModel中的所有数据.当程序运行时,首先GUI有一个按钮,我们在其中单击它并获取底层TableModel中的所有数据.但我面临两个问题.首先在GUI2类中,有时它会像这样打开.

有时它显示这样

http://imageshack.com/i/p3gBDt9Ej

我不知道为什么会这样.第二个问题是当我们从表中选择任何行并单击DeleteSelectedRow按钮时它会删除该行.此按钮在GUI2类中有一个ActionListener.但我想要的是我删除行时自动更新表.我怎样才能做到这一点？

第一个GUI的类

public class Gui extends JFrame {
    private static Connector conni;
    private Connection conn = null;
    private JButton bt;
    private JPanel panel;

    public Gui() {
        super("Frame");
        panel = new JPanel();
        bt = new JButton("Connect to Database 'World'");
        panel.add(bt);
        bt.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {

                conn = conni.Connector();

                if (conn != null) {
                    dispose();
                    new Gui2(conn);

                } else {
                    System.out.println("Return false");

                }

            }

        });
        add(panel);

        pack();
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setVisible(true);

    }

}

连接器类

public class Connector {

    private static Connection conn = null;

    public static Connection Connector() {
        String data = "jdbc:mysql://localhost/world";
        String user = "root";
        String pass = "toot";
        try {
            conn = DriverManager.getConnection(data, user, pass);

        } catch (Exception e) {

            JOptionPane.showMessageDialog(null, e.getMessage());

        }
        if (conn != null) {

            System.out.println("Connection Suceess");
            return conn;

        } else {

            return conn;

        }

    }

}

第二个GUI2的类

public class Gui2 extends JFrame {
    private Statement state = null;
    private ResultSet rs = null;

    private JButton bt, delete;
    private JTextField text;
    private JPanel panel;
    private GridBagLayout layout;
    private GridBagConstraints constraints;

    public Gui2(Connection conn) {
        layout = new GridBagLayout();
        constraints = new GridBagConstraints();
        panel = new JPanel();
        panel.setLayout(layout);

        text = new JTextField(15);
        bt = new JButton("Submit Query");
        delete = new JButton("Delete Selected Row");
        constraints.insets = new Insets(5, 2, 5, 10);
        constraints.gridy = 0;// row 0
        constraints.gridx = 0;// column 0
        // TextField add on JPanel with given constraints
        panel.add(text, constraints);
        constraints.gridx++;
        panel.add(delete, constraints);
        constraints.gridx++;
        panel.add(bt, constraints);

        // North BorderLayout
        add(panel, BorderLayout.NORTH);

        try {
            state = conn.createStatement();
            rs = state.executeQuery("select * from city");
        } catch (SQLException e) {

            JOptionPane.showMessageDialog(null, e.getMessage());
        }

        JTable table = new JTable();
        JScrollPane spane = new JScrollPane(table);

        add(spane, BorderLayout.CENTER);

        table.setModel(new TableModel(rs));

        delete.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {

                int rowIndex = table.getSelectedRow();

                Object columnIndexValue = table.getModel().getValueAt(rowIndex, 0);

                String columnName = table.getModel().getColumnName(0);

                String query = "delete from world.city" + " where " + columnName + "=" + columnIndexValue;

                try {

                    PreparedStatement pre = conn.prepareStatement(query);

                    pre.executeUpdate();

                    JOptionPane.showMessageDialog(null, "Row Deleted Successfully");
                } catch (Exception e1) {
                    JOptionPane.showMessageDialog(null, e1.getMessage());
                }

            }

        });

        setSize(817, 538);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setVisible(true);

    }

}

Tablemodel类

public class TableModel extends AbstractTableModel {

    private List ColumnHeader;
    private List tableData;
    private List rowData;

    private int totalcolumn;

    public TableModel(ResultSet rs) {

        try {

            ResultSetMetaData meta = rs.getMetaData();

            totalcolumn = meta.getColumnCount();

            ColumnHeader = new ArrayList(totalcolumn);

            tableData = new ArrayList();

            for (int i = 1; i <= totalcolumn; i++) {
                ColumnHeader.add(meta.getColumnName(i));

            }
        } catch (Exception e) {

            JOptionPane.showMessageDialog(null, e.getMessage());
        }

        SwingWorker<Boolean, List<Object>> worker = new SwingWorker<Boolean, List<Object>>() {

            @Override
            protected Boolean doInBackground() throws Exception {

                while (rs.next()) {

                    rowData = new ArrayList(totalcolumn);
                    for (int i = 1; i <= totalcolumn; i++) {
                        rowData.add(rs.getObject(i));
                    }
                    publish(rowData);


                }

                return true;

            }

            @Override
            protected void process(List chunks) {
                tableData.add(chunks);

            }

            @Override
            protected void done() {
                try {
                    Boolean status = get();
                    JOptionPane.showMessageDialog(null, "Task is DONE");
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (ExecutionException e) {
                    e.printStackTrace();
                }
            }

        };

        worker.execute();
    }// constructor end



    @Override
    public int getColumnCount() {

        return ColumnHeader.size();
    }

    public String getColumnName(int columnIndex) {
        return (String) ColumnHeader.get(columnIndex);

    }

    @Override
    public int getRowCount() {

        return tableData.size();
    }

    @Override
    public Object getValueAt(int rowIndex, int columnIndex) {

        List rowData2 = (List) tableData.get(rowIndex);

        return rowData2.get(columnIndex);
    }

}

解决方法:

因为数据库访问本质上是异步的,所以你肯定希望在后台检索行以避免阻塞event dispatch thread; SwingWorker使这相对容易.获取doInBackground(),publish()临时结果的实现中的行,并将它们添加到process()实现中的表模型中. 0700显示了一个概述附带好处的完整示例.该示例循环遍历文件,但您可以替换ResultSet操作.

while (rs.next()) {
    //collect row data
    publish(rowData);
}

将tableData.add()推迟到process()的实现.

关注自定义TableModel与其包含的SwingWorker之间的交互,以下complete example创建一个具有N行的测试数据库,并显示一个JTable,显示该表的查询结果.特别是,

> JDBCModel扩展了AbstractTableModel.为简单起见,模型的数据存储在List< Row>中,ResultSetMetaData用于列名.作为一个更抽象的替代方案,请参阅Apache Commons DbUtils,它使用Class Literals as Runtime-Type Tokens和ResultSetMetaData来安全地创建行数据的实例.
> JDBCModel将行检索委托给私有JDBCWorker;它在从ResultSet检索的每一行上调用publish();因为process()在EDT上运行,所以worker可以使用fireTableRowsInserted()优化代表父模型触发的表模型事件的数量.
>同样,delete()的实现应该驻留在JDBCModel中,而不是GUI中;在从数据库中成功删除行并从数据中删除之后,应该使用fireTableRowsDeleted().
>将Thread.sleep()添加到worker的后台循环中,以查看人为增加延迟的效果.
>使用setProgress()和PropertyChangeListener(如here所示)显示进度;完成()时的JOptionPane可能是多余的.
>重写getPreferredScrollableViewportSize()以自定义包含JScrollPane的表的大小.
>避免使用类名,例如TableModel,与常见的API名称冲突.
>检查在视图中实现实时filtering的变体here.

import java.awt.Dimension;
import java.awt.EventQueue;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.SwingWorker;
import javax.swing.table.AbstractTableModel;

/**
 * @see https://stackoverflow.com/a/34742409/230513
 * @see https://stackoverflow.com/a/24762078/230513
 */
public class WorkerTest {

    private static final int N = 1_000;
    private static final String URL = "jdbc:h2:mem:test";
    private static final Random r = new Random();

    private void display() {
        JFrame f = new JFrame("WorkerTest");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        createTestDatabase(N);
        JDBCModel model = new JDBCModel(getConnection(), "select * from city");
        f.add(new JScrollPane(new JTable(model) {

            @Override
            public Dimension getPreferredScrollableViewportSize() {
                return new Dimension(320, 240);
            }
        }));
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    private static class Row {
        int ID;
        String name;
    }

    private static class JDBCModel extends AbstractTableModel {

        private final List<Row> data = new ArrayList<>();
        private ResultSet rs = null;
        private ResultSetMetaData meta;

        public JDBCModel(Connection conn, String query) {
            try {
                Statement s = conn.createStatement();
                rs = s.executeQuery(query);
                meta = rs.getMetaData();
                JDBCWorker worker = new JDBCWorker();
                worker.execute();
            } catch (SQLException e) {
                e.printStackTrace(System.err);
            }
        }

        @Override
        public int getRowCount() {
            return data.size();
        }

        @Override
        public int getColumnCount() {
            try {
                return meta.getColumnCount();
            } catch (SQLException e) {
                e.printStackTrace(System.err);
            }
            return 0;
        }

        @Override
        public Object getValueAt(int rowIndex, int colIndex) {
            Row row = data.get(rowIndex);
            switch (colIndex) {
                case 0:
                    return row.ID;
                case 1:
                    return row.name;
            }
            return null;
        }

        @Override
        public String getColumnName(int colIndex) {
            try {
                return meta.getColumnName(colIndex + 1);
            } catch (SQLException e) {
                e.printStackTrace(System.err);
            }
            return null;
        }

        private class JDBCWorker extends SwingWorker<List<Row>, Row> {

            @Override
            protected List<Row> doInBackground() {
                try {
                    while (rs.next()) {
                        Row r = new Row();
                        r.ID = rs.getInt(1);
                        r.name = rs.getString(2);
                        publish(r);
                    }
                } catch (SQLException e) {
                    e.printStackTrace(System.err);
                }
                return data;
            }

            @Override
            protected void process(List<Row> chunks) {
                int n = getRowCount();
                for (Row row : chunks) {
                    data.add(row);
                }
                fireTableRowsInserted(n, n + chunks.size());
            }
        }
    }

    private static void createTestDatabase(int n) {
        Connection conn = getConnection();
        try {
            Statement st = conn.createStatement();
            st.execute("create table city(id integer, name varchar2)");
            PreparedStatement ps = conn.prepareStatement(
                "insert into city values (?, ?)");
            for (int i = 0; i < n; i++) {
                ps.setInt(1, i);
                ps.setString(2, (char) ('A' + r.nextInt(26))
                    + String.valueOf(r.nextInt(1_000_000)));
                ps.execute();
            }
        } catch (SQLException ex) {
            ex.printStackTrace(System.err);
        }
    }

    private static Connection getConnection() {
        try {
            return DriverManager.getConnection(URL, "", "");
        } catch (SQLException e) {
            e.printStackTrace(System.err);
        }
        return null;
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new WorkerTest()::display);
    }
}

标签：java,jdbc,swing,jtable,abstracttablemodel
来源： https://codeday.me/bug/20190915/1804806.html

本站声明： 1. iCode9 技术分享网（下文简称本站）提供的所有内容，仅供技术学习、探讨和分享；
2. 关于本站的所有留言、评论、转载及引用，纯属内容发起人的个人观点，与本站观点和立场无关；
3. 关于本站的所有言论和文字，纯属内容发起人的个人观点，与本站观点和立场无关；
4. 本站文章均是网友提供，不完全保证技术分享内容的完整性、准确性、时效性、风险性和版权归属；如您发现该文章侵犯了您的权益，可联系我们第一时间进行删除；
5. 本站为非盈利性的个人网站，所有内容不会用来进行牟利，也不会利用任何形式的广告来间接获益，纯粹是为了广大技术爱好者提供技术内容和技术思想的分享性交流网站。