在Swing应用程序中，我有时需要支持对加载缓慢的大型面向行的文本文件的只读访问：日志，转储，跟踪等。对于少量数据，{{3} } Document和JTextComponent很好，如suitable所示。我理解浏览大量数据的人为限制，但有问题的东西似乎总是在最大的文件中。对于10-100兆字节，百万行范围内的大量文本，是否有任何实用的替代方案？
答案 0 :(得分：23)
由于尺寸原因，您肯定希望在后台加载文件以避免阻止event dispatch thread; SwingWorker是一种常见的选择。请考虑更新Document并在TableModel的行中显示文本行，而不是使用JTable。这提供了几个优点：
结果将立即开始显示，并且感知延迟会减少。
JTable使用rendering的flyweight模式，可以很好地扩展到数兆字节的百万行范围。
您可以在读取输入时解析输入以创建任意列结构。
您可以利用JTable的{{3}}功能，sorting and filtering。
您可以使用example专注于一行。
附录：为方便起见，下面的示例使用DefaultTableModel。要缩小TablePopupEditor，请展开AbstractTableModel并管理List<String>或List<RowData>，如图overhead所示。该示例显示了不确定的进度;显示中间进度的更改显示为here。
代码：
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.beans.PropertyChangeEvent;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JProgressBar;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.SwingWorker;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableModel;
/**
* @see https://stackoverflow.com/a/25526869/230513
*/
public class DisplayLog {
private static final String NAME = "/var/log/install.log";
private static class LogWorker extends SwingWorker<TableModel, String> {
private final File file;
private final DefaultTableModel model;
private LogWorker(File file, DefaultTableModel model) {
this.file = file;
this.model = model;
model.setColumnIdentifiers(new Object[]{file.getAbsolutePath()});
}
@Override
protected TableModel doInBackground() throws Exception {
BufferedReader br = new BufferedReader(new FileReader(file));
String s;
while ((s = br.readLine()) != null) {
publish(s);
}
return model;
}
@Override
protected void process(List<String> chunks) {
for (String s : chunks) {
model.addRow(new Object[]{s});
}
}
}
private void display() {
JFrame f = new JFrame("DisplayLog");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
DefaultTableModel model = new DefaultTableModel();
JTable table = new JTable(model);
JProgressBar jpb = new JProgressBar();
f.add(jpb, BorderLayout.NORTH);
f.add(new JScrollPane(table));
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
LogWorker lw = new LogWorker(new File(NAME), model);
lw.addPropertyChangeListener((PropertyChangeEvent e) -> {
SwingWorker.StateValue s = (SwingWorker.StateValue) e.getNewValue();
jpb.setIndeterminate(s.equals(SwingWorker.StateValue.STARTED));
});
lw.execute();
}
public static void main(String[] args) {
EventQueue.invokeLater(() -> {
new DisplayLog().display();
});
}
}
答案 1 :(得分：6)
我会将问题分开。
第一个是模型 - 文档构建速度
第二个是Document rendering - 构建视图树来表示Document。
问题是你是否需要像关键字一样的字体效果？
我将从文档构建部分开始。通过EditorKit.read（）读取文件的IMHO即使对于大文件也应该快速。我会使用PainDocument来检查纯模型是否构建得足够快，适合您的应用程序。如果是的话，只需使用Document作为模型。如果没有实现自己的Document接口，因为AbstractDocument有很多方法可以进行更新处理（例如writeLock）。
当我们足够快地加载文档时，我们必须解决文档渲染问题。默认情况下，javax.swing.text中使用的视图非常灵活。它们被设计为要扩展的基类 - 因此有很多我们不需要的代码。例如。测量。
对于我将使用Monospaced字体的功能，我们不需要换行，因此视图的测量值很快=最长行字符数* char widht。
高度也是字符高度*行数。
所以我们的PLainTextViewReplacement非常快。此外，我们不必渲染整个视图，只需在滚动窗格中显示一个片段。因此，渲染速度可能会快得多。
当然，应该有很多工作来提供正确的插入符导航，选择等。
答案 2 :(得分：0)
当我在努力解决类似的用例时，我实现了一个简单的分页解决方案。它远非完美，但也许有人发现它有用。
与jtextarea结合使用可以正常工作，但与JEditorPane结合使用时，性能会很糟糕。
如果有人想提供更好的解决方案，我想知道。
package net.ifao.tools.arcticrequester.gui.panel;
import java.awt.Adjustable;
import java.awt.event.AdjustmentEvent;
import java.awt.event.AdjustmentListener;
import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.io.StringReader;
import java.nio.channels.FileChannel;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingDeque;
import javax.swing.JEditorPane;
import javax.swing.JScrollPane;
import javax.swing.text.Document;
import javax.swing.text.EditorKit;
import javax.swing.text.JTextComponent;
/**
* A class that manages the visibility of file content visualized with a textarea within a scrollbar.
* Approx. 2050 lines from the file are visible at a time. Data is loaded from a file and
* displayed while the user is scrolling. The chunks are loaded dynamically.
*
* @author dostricki
*
*/
public class VisibilityManager
implements AdjustmentListener
{
private int lastLoadedLineFrom;
private int lastLoadedLineTo;
private int numberOfLines = 0;
private File file;
private boolean enabled = false;
private boolean showLines = false;
// load 1000 lines before the first visible line
// and 1000 lines after the last vissible line
private static final int LOAD_LINES_BEFORE_AND_AFTER_VIEWPORT = 1000;
// margin until when no load is triggered.
// moving the viewport more then 900 lines up or down should trigger a reload
private static final int VIEWPORT_LINES_MOVE_THRASHOLD = 900;
private JScrollPane scrollPane;
private JTextComponent textComponent;
private final BlockingQueue<Adjustable> queue;
public VisibilityManager(JScrollPane scrollPane, JTextComponent textArea)
{
this.scrollPane = scrollPane;
this.textComponent = textArea;
queue = new LinkedBlockingDeque<>();
startConsumer();
scrollPane.getVerticalScrollBar().addAdjustmentListener(this);
}
private void startConsumer()
{
Thread scrollEventConsumer = new Thread()
{
@Override
public void run()
{
while (true) {
try {
// if multiple events occured just process one
queue.take();
if (!queue.isEmpty()) {
List<Adjustable> events = new ArrayList<>();
queue.drainTo(events);
//System.out.println("Handling scroll event. " + events.size() + " queued events dropped");
}
doHandleScrollEvent();
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
}
};
scrollEventConsumer.start();
}
public void setFile(File file)
{
this.file = file;
try {
this.numberOfLines = countNumberOfLines(file);
}
catch (IOException e1) {
e1.printStackTrace();
}
int showLineMax = Math.min(getNumberOfLines(), 100);
// show the first chunk immediately
showLinesBuffererdReader(1, showLineMax, 0);
this.enabled = true;
}
/**
* precalculates the number of lines in the document - necessary
* to replace the correct amount of preceeding and following
* lines with EOL's so that the height of the scrollpane does never change.
*
* @param file
* @return
* @throws IOException
*/
private int countNumberOfLines(File file)
throws IOException
{
int numberOfLines = 0;
//@formatter:off
try (BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(file),StandardCharsets.UTF_8));) {
while (reader.ready()) {
reader.readLine();
++numberOfLines;
}
}
//@formatter:on
return numberOfLines;
}
/****************************************
* Getter
****************************************/
public int getNumberOfLines()
{
return numberOfLines;
}
public int getNumberOfLinesBuffer()
{
return LOAD_LINES_BEFORE_AND_AFTER_VIEWPORT;
}
public boolean isEnabled()
{
return enabled;
}
/****************************************
* Setter
****************************************/
public void setLastLoadedLines(int lineFrom, int lineTo)
{
this.lastLoadedLineFrom = lineFrom;
this.lastLoadedLineTo = lineTo;
}
public void setEnabled(boolean enabled)
{
this.enabled = enabled;
}
public void setShowLines(boolean showLines)
{
this.showLines = showLines;
}
/****************************************
* Calculation
****************************************/
private boolean needsUpdate(int fromLine, int toLine)
{
boolean isBefore = fromLine < (this.lastLoadedLineFrom - VIEWPORT_LINES_MOVE_THRASHOLD);
boolean isAfter = toLine > (this.lastLoadedLineTo + VIEWPORT_LINES_MOVE_THRASHOLD);
if (isBefore || isAfter) {
return true;
} else {
return false;
}
}
private void showLinesBuffererdReader(int from, int to, int firstLineVisible)
{
//load also the buffer lines before
from = from - getNumberOfLinesBuffer();
//make sure it's valid
from = Math.max(1, from);
// load also the buffer lines after
to = to + getNumberOfLinesBuffer();
//make sure it's valid
to = Math.min(getNumberOfLines(), to);
FileChannel fileChannel = null;
try (BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(file)))) {
StringBuffer content = new StringBuffer();
int newCaretPosition = 0;
// fill leading empty lines
for (long i = 1; i < from; ++i) {
if (i == firstLineVisible) {
newCaretPosition = content.length() + 1;
}
if (showLines) {
content.append(i).append(": ");
}
content.append('\n');
}
// read/write lines with content
int j = 0;
while (reader.ready() && j <= to) {
++j;
String line = reader.readLine();
if (j >= from && j <= to) {
if (j == firstLineVisible) {
newCaretPosition = content.length() + 1;
}
if (showLines) {
content.append(j).append(": ");
}
content.append(line).append('\n');
}
}
// fill trailing empty lines
for (int i = to + 1; i <= getNumberOfLines(); ++i) {
if (i == firstLineVisible) {
newCaretPosition = content.length() + 1;
}
if (showLines) {
content.append(i).append(": ");
}
content.append('\n');
}
updateTextInUI(content);
// workaround for page up/down - it changes the caret position
// so we are re-setting it to the first visible line
// scrolling by scrollbars does not change the caret
//textComponent.setCaretPosition(newCaretPosition);
}
catch (IOException e) {
e.printStackTrace();
}
finally {
try {
if (fileChannel != null) {
fileChannel.close();
}
}
catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* @param content
* @throws IOException
*/
private void updateTextInUI(StringBuffer content)
throws IOException
{
if (textComponent instanceof JEditorPane) {
JEditorPane edit = ((JEditorPane) textComponent);
EditorKit editorKit = edit.getEditorKit();
Document createDefaultDocument = editorKit.createDefaultDocument();
createDefaultDocument.putProperty("IgnoreCharsetDirective", Boolean.TRUE);
try {
editorKit.read(new StringReader(content.toString()), createDefaultDocument, 0);
}
catch (Exception e) {
ByteArrayOutputStream out = new ByteArrayOutputStream();
e.printStackTrace(new PrintStream(out));
edit.setText(new String(out.toByteArray()));
}
edit.setDocument(createDefaultDocument);
} else {
textComponent.setText(content.toString());
}
}
/****************************************
* Eventing
****************************************/
/**
* fired when scrolling happens in any of the cases and ways.
* Events are cached through a queue so that simultanious events
* don't trigger unnecessary update actions
* @see java.awt.event.AdjustmentListener#adjustmentValueChanged(java.awt.event.AdjustmentEvent)
*/
@Override
public void adjustmentValueChanged(AdjustmentEvent evt)
{
Adjustable source = evt.getAdjustable();
if (evt.getValueIsAdjusting()) {
return;
}
if (source != null) {
try {
queue.put(source);
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
}
private void doHandleScrollEvent()
{
// determine which lines to request to be loaded into the
int height = this.scrollPane.getVerticalScrollBar().getMaximum();
int lines = getNumberOfLines();
if (lines == 0) {
return;
}
float heightPerLine = height / lines;
int visibleLines = Math.round(this.scrollPane.getVerticalScrollBar().getVisibleAmount() / heightPerLine);
int firstLineVisible = (int) Math.ceil(this.scrollPane.getVerticalScrollBar().getValue() / heightPerLine);
int fromLine = Math.max(firstLineVisible, 1);
if (fromLine > lines) {
fromLine = lines;
}
int toLine = Math.min(firstLineVisible + visibleLines, lines);
if (needsUpdate(fromLine, toLine)) {
if (enabled) {
setLastLoadedLines(fromLine, toLine);
showLinesBuffererdReader(fromLine, toLine, firstLineVisible);
}
}
}
}
用法：
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.io.File;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.EmptyBorder;
import javax.swing.text.DefaultCaret;
import net.ifao.tools.arcticrequester.gui.panel.VisibilityManager;
public class TestFrame
extends JFrame
implements MouseListener
{
private VisibilityManager visibilityManager;
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
@Override
public void run()
{
try {
TestFrame frame = new TestFrame();
frame.setVisible(true);
}
catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public TestFrame()
{
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
}
catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException e2) {
// TODO Auto-generated catch block
e2.printStackTrace();
}
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 650, 500);
JPanel contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(new BorderLayout(0, 0));
JTextArea textArea = new JTextArea();
textArea.setEditable(false);
textArea.addMouseListener(this);
textArea.setAutoscrolls(false);
textArea.setCaretPosition(0);
DefaultCaret caret = (DefaultCaret) textArea.getCaret();
caret.setUpdatePolicy(DefaultCaret.NEVER_UPDATE);
JScrollPane scrollPane = new JScrollPane(textArea);
contentPane.add(scrollPane);
visibilityManager = new VisibilityManager(scrollPane, textArea);
visibilityManager.setShowLines(true);
File file = new File("C:/iFAO/workspaces/polaris2/git/requester/ArcticRequester/src/test/java/responseview_20200603.tmp");
visibilityManager.setFile(file);
this.dispose();
}
/**
* @see java.awt.event.MouseListener#mouseClicked(java.awt.event.MouseEvent)
*/
@Override
public void mouseClicked(MouseEvent e)
{
boolean doScroll = !visibilityManager.isEnabled();
this.visibilityManager.setEnabled(doScroll);
System.out.println("scrolling set to " + doScroll);
}
/**
* @see java.awt.event.MouseListener#mousePressed(java.awt.event.MouseEvent)
*/
@Override
public void mousePressed(MouseEvent e)
{
// TODO Auto-generated method stub
}
/**
* @see java.awt.event.MouseListener#mouseReleased(java.awt.event.MouseEvent)
*/
@Override
public void mouseReleased(MouseEvent e)
{
// TODO Auto-generated method stub
}
/**
* @see java.awt.event.MouseListener#mouseEntered(java.awt.event.MouseEvent)
*/
@Override
public void mouseEntered(MouseEvent e)
{
// TODO Auto-generated method stub
}
/**
* @see java.awt.event.MouseListener#mouseExited(java.awt.event.MouseEvent)
*/
@Override
public void mouseExited(MouseEvent e)
{
// TODO Auto-generated method stub
}
}