downloadstablemodel.java

这是Java编程艺术一书附带的源代码

import java.util.*;
import javax.swing.*;
import javax.swing.table.*;

// This class manages the download table's data.
class DownloadsTableModel extends AbstractTableModel
  implements Observer
{
  // These are the names for the table's columns.
  private static final String[] columnNames = {"URL", "Size",
    "Progress", "Status"};

  // These are the classes for each column's values.
  private static final Class[] columnClasses = {String.class,
    String.class, JProgressBar.class, String.class};

  // The table's list of downloads.
  private ArrayList downloadList = new ArrayList();

  // Add a new download to the table.
  public void addDownload(Download download) {
    // Register to be notified when the download changes.
    download.addObserver(this);

    downloadList.add(download);

    // Fire table row insertion notification to table.
    fireTableRowsInserted(getRowCount() - 1, getRowCount() - 1);
  }

  // Get a download for the specified row.
  public Download getDownload(int row) {
    return (Download) downloadList.get(row);
  }

  // Remove a download from the list.
  public void clearDownload(int row) {
    downloadList.remove(row);

    // Fire table row deletion notification to table.
    fireTableRowsDeleted(row, row);
  }

  // Get table's column count.
  public int getColumnCount() {
    return columnNames.length;
  }

  // Get a column's name.
  public String getColumnName(int col) {
     return columnNames[col];
  }

  // Get a column's class.
  public Class getColumnClass(int col) {
    return columnClasses[col];
  }

  // Get table's row count.
  public int getRowCount() {
    return downloadList.size();
  }

  // Get value for a specific row and column combination.
  public Object getValueAt(int row, int col) {
    Download download = (Download) downloadList.get(row);
    switch (col) {
      case 0: // URL
        return download.getUrl();
      case 1: // Size
        int size = download.getSize();
        return (size == -1) ? "" : Integer.toString(size);
      case 2: // Progress
        return new Float(download.getProgress());
      case 3: // Status
        return Download.STATUSES[download.getStatus()];
    }
    return "";
  }

  /* Update is called when a Download notifies its
     observers of any changes */
  public void update(Observable o, Object arg) {
    int index = downloadList.indexOf(o);

    // Fire table row update notification to table.
    fireTableRowsUpdated(index, index);
  }
}