[英]Load data from txt file to JTable
如果将数据从JTable 保存到txt文件,看起来有什么简单的方法可以从txt文件加载数据:
for (int row = 0; row < table.getRowCount(); row++) {
for (int col = 0; col < table.getColumnCount(); col++) {
out.println(table.getColumnName(col));
out.print(": ");
out.println(table.getValueAt(row, col));
或者,如果用户退出程序并再次运行,可能是另一种将数据保留在JTable中的方法吗?
非常感谢您的帮助。
您可以考虑序列化JTable。 这是将整个对象保存到文件的内置过程。
从JDK 4开始,您可以使用XMLEncoder
提供永久存储,并使用XMLDecoder
重新创建要保存的对象。 您需要创建一个PersistenceDelegate
来辅助数据的编码和解码。
这是DefaultTableModel
的示例:
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)},
{"bbb\u2600", 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 DefaultTableModelPersistenceDelegate2());
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);
}
}
//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;
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));
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));
}
}
}
上面的代码是以下解决方案的更完整示例: 如何使用Java中的XMLEndcoder在XML文件中的数据中写入JTable状态
示例中的文本区域仅用于显示要保存的数据的XML文件的内容。
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