将 Interactive JTable 的内容保存到 .txt 文件以在下次运行时读取 [英] Saving content of Interactive JTable to .txt file to read it upon next run

问题描述

大家好，我目前正在编写一个向用户显示 JTable 的程序，以便他们可以在表格窗口中输入一些数据.问题是，我不知道如何保存任何数据，所以当应用程序再次运行时可以重新打开数据.我希望在应用关闭时自动保存数据，但如果需要，我很乐意使用按钮.

Hey guys I am currently writing a program that displays a JTable to the user, so they can input some data into the table window. Problem is, I can't figure out how to save any data, so the data can be re-opened when the app is run again. I would prefer the data to be saved automatically when the app is closed, but I'm happy to use a button if I need to.

推荐答案

我不知道如何保存任何数据，

I can't figure out how to save any data,

从 JTable API(和所有 Swing 组件)您将看到:

From the JTable API (and all Swing components) you will see:

警告:此类的序列化对象将与未来的 Swing 版本不兼容......从 1.4 开始，对所有 JavaBeans™ 的长期存储的支持已添加到 java.beans 包中.请参阅 XMLEncoder.

这是一个使用 XMLEncoder 的示例:

Here is an example using XMLEncoder:

//  Following code is a more complete version of:
//  http://stackoverflow.com/q/26250939/131872

import java.awt.*;
import java.awt.event.*;
import java.beans.*;
import java.io.*;
import java.util.Vector;
import javax.swing.*;
import javax.swing.table.*;

public class DefaultTableModelPersistenceDelegateTest
{
    private File file = new File("TableModel.xml");
    private final JTextArea textArea = new JTextArea();

    private final String[] columnNames = {"Column1", "Column2"};

    private final Object[][] data =
    {
        {"aaa", new Integer(1)},
        {"bbbu2600", new Integer(2)}
    };

    private DefaultTableModel model = new DefaultTableModel(data, columnNames);
    private final JTable table = new JTable(model);

    public JComponent makeUI()
    {
        model.setColumnCount(5);
        JSplitPane sp = new JSplitPane(JSplitPane.VERTICAL_SPLIT);
        sp.setResizeWeight(.3);
        sp.setTopComponent(new JScrollPane(table));
        sp.setBottomComponent(new JScrollPane(textArea));

        JPanel p = new JPanel();
        p.add(new JButton(new AbstractAction("XMLEncoder")
        {
            @Override
            public void actionPerformed(ActionEvent e)
            {
                try
                {
                    OutputStream os = new BufferedOutputStream(new FileOutputStream(file));
                    XMLEncoder xe = new XMLEncoder(os);
                    xe.setPersistenceDelegate(DefaultTableModel.class, new DefaultTableModelPersistenceDelegate());
                    xe.writeObject(model);
                    xe.close();

                    Reader r = new BufferedReader(new InputStreamReader(new FileInputStream(file), "UTF-8"));
                    textArea.read(r, null);
                }
                catch (IOException ex)
                {
                    ex.printStackTrace();
                }
            }
        }));

        p.add(new JButton(new AbstractAction("XMLDecoder")
        {
            @Override
            public void actionPerformed(ActionEvent e)
            {
                try
                {
                    InputStream is = new BufferedInputStream( new FileInputStream( file ));
                    XMLDecoder xd = new XMLDecoder(is);
                    model = (DefaultTableModel)xd.readObject();
                    table.setModel(model);
                }
                catch (IOException ex)
                {
                    ex.printStackTrace();
                }
            }
        }));

        p.add(new JButton(new AbstractAction("clear")
        {
            @Override
            public void actionPerformed(ActionEvent e)
            {
                model = new DefaultTableModel();
                table.setModel(model);
            }
        }));

        JPanel pnl = new JPanel(new BorderLayout());
        pnl.add(sp);
        pnl.add(p, BorderLayout.SOUTH);
        return pnl;
    }

    public static void main(String[] args)
    {
        EventQueue.invokeLater(new Runnable()
        {
            @Override public void run()
            {
                createAndShowGUI();
            }
        });
    }

    public static void createAndShowGUI()
    {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        f.getContentPane().add(new DefaultTableModelPersistenceDelegateTest().makeUI());
        f.setSize(420, 340);
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }
}

//  See following link for more information on Using XMLEncoder:
//  http://www.oracle.com/technetwork/java/persistence4-140124.html

class DefaultTableModelPersistenceDelegate extends DefaultPersistenceDelegate
{
    //  Initially creates an empty DefaultTableModel. The columns are created
    //  and finally each row of data is added to the model.

    @Override
    protected void initialize(Class<?> type, Object oldInstance, Object newInstance, Encoder encoder)
    {
        DefaultTableModel model= (DefaultTableModel)oldInstance;

        //  Create XML to restore the column names

        Vector<String> columnNames = new Vector<String>(model.getColumnCount());

        for (int i = 0; i < model.getColumnCount(); i++)
        {
            columnNames.add( model.getColumnName(i) );
        }

        Object[] columnNamesData = new Object[] { columnNames };
        encoder.writeStatement(new Statement(oldInstance, "setColumnIdentifiers", columnNamesData));

        //  Create XML to restore row data

        Vector row = model.getDataVector();

        for (int i = 0; i < model.getRowCount(); i++)
        {
            Object[] rowData = new Object[] { row.get(i) };
            encoder.writeStatement(new Statement(oldInstance, "addRow", rowData));
        }
    }
}

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