Java JTextPane JScrollPane显示问题 [英] Java JTextPane JScrollPane Display Issue
问题描述
以下类实现了chatGUI。当它运行正常时，屏幕看起来像这样：
The following class implements a chatGUI. When it runs okay the screen looks like this:
精美ChatGUI http://img21.imageshack.us/img21/7177/rightchat.jpg
问题很常见，当我输入大长度的文本即。 50 - 100 chars gui变得疯狂。聊天记录框缩小，如此
The problem is very often when i enter text of large length ie. 50 - 100 chars the gui goes crazy. the chat history box shrinks as shown in this
图片http://img99.imageshack.us/img99/6962/errorgui.jpg 。
关于造成这种情况的原因是什么？
Any ideas regarding what is causing this?
谢谢。
PS：下面附带的类是完整的代码。你可以复制它并在你的计算机上编译，看看到底是什么意思。
PS: the attached class below is complete code. you can copy it and compile on your computer to see exactly what i mean.
注意：一旦GUI发疯，那么如果我点击清除按钮，历史记录窗口清除并且GUI返回再次正确显示。
NOTE: once the GUI goes crazy then if i hit the "Clear" button the history window clears and the GUI goes back to being correctly displayed again.
package Sartre.Connect4;
import javax.swing.*;
import java.net.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.text.StyledDocument;
import javax.swing.text.Style;
import javax.swing.text.StyleConstants;
import javax.swing.text.BadLocationException;
import java.io.BufferedOutputStream;
import javax.swing.text.html.HTMLEditorKit;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.FileNotFoundException;
import javax.swing.filechooser.FileNameExtensionFilter;
import javax.swing.JFileChooser;
/**
* Chat form class
* @author iAmjad
*/
public class ChatGUI extends JDialog implements ActionListener {
/**
* Used to hold chat history data
*/
private JTextPane textPaneHistory = new JTextPane();
/**
* provides scrolling to chat history pane
*/
private JScrollPane scrollPaneHistory = new JScrollPane(textPaneHistory);
/**
* used to input local message to chat history
*/
private JTextPane textPaneHome = new JTextPane();
/**
* Provides scrolling to local chat pane
*/
private JScrollPane scrollPaneHomeText = new JScrollPane(textPaneHome);
/**
* JLabel acting as a statusbar
*/
private JLabel statusBar = new JLabel("Ready");
/**
* Button to clear chat history pane
*/
private JButton JBClear = new JButton("Clear");
/**
* Button to save chat history pane
*/
private JButton JBSave = new JButton("Save");
/**
* Holds contentPane
*/
private Container containerPane;
/**
* Layout GridBagLayout manager
*/
private GridBagLayout gridBagLayout = new GridBagLayout();
/**
* GridBagConstraints
*/
private GridBagConstraints constraints = new GridBagConstraints();
/**
* Constructor for ChatGUI
*/
public ChatGUI(){
setTitle("Chat");
// set up dialog icon
URL url = getClass().getResource("Resources/SartreIcon.jpg");
ImageIcon imageIcon = new ImageIcon(url);
Image image = imageIcon.getImage();
this.setIconImage(image);
this.setAlwaysOnTop(true);
setLocationRelativeTo(this.getParent());
//////////////// End icon and placement /////////////////////////
// Get pane and set layout manager
containerPane = getContentPane();
containerPane.setLayout(gridBagLayout);
/////////////////////////////////////////////////////////////
//////////////// Begin Chat History //////////////////////////////
textPaneHistory.setToolTipText("Chat History Window");
textPaneHistory.setEditable(false);
textPaneHistory.setPreferredSize(new Dimension(350,250));
scrollPaneHistory.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
scrollPaneHistory.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
// fill Chat History GridBagConstraints
constraints.gridx = 0;
constraints.gridy = 0;
constraints.gridwidth = 10;
constraints.gridheight = 10;
constraints.weightx = 100;
constraints.weighty = 100;
constraints.fill = GridBagConstraints.BOTH;
constraints.anchor = GridBagConstraints.CENTER;
constraints.insets = new Insets(10,10,10,10);
constraints.ipadx = 0;
constraints.ipady = 0;
gridBagLayout.setConstraints(scrollPaneHistory, constraints);
// add to the pane
containerPane.add(scrollPaneHistory);
/////////////////////////////// End Chat History ///////////////////////
///////////////////////// Begin Home Chat //////////////////////////////
textPaneHome.setToolTipText("Home Chat Message Window");
textPaneHome.setPreferredSize(new Dimension(200,50));
textPaneHome.addKeyListener(new MyKeyAdapter());
scrollPaneHomeText.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
scrollPaneHomeText.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
// fill Chat History GridBagConstraints
constraints.gridx = 0;
constraints.gridy = 10;
constraints.gridwidth = 6;
constraints.gridheight = 1;
constraints.weightx = 100;
constraints.weighty = 100;
constraints.fill = GridBagConstraints.BOTH;
constraints.anchor = GridBagConstraints.CENTER;
constraints.insets = new Insets(10,10,10,10);
constraints.ipadx = 0;
constraints.ipady = 0;
gridBagLayout.setConstraints(scrollPaneHomeText, constraints);
// add to the pane
containerPane.add(scrollPaneHomeText);
////////////////////////// End Home Chat /////////////////////////
///////////////////////Begin Clear Chat History ////////////////////////
JBClear.setToolTipText("Clear Chat History");
// fill Chat History GridBagConstraints
constraints.gridx = 6;
constraints.gridy = 10;
constraints.gridwidth = 2;
constraints.gridheight = 1;
constraints.weightx = 100;
constraints.weighty = 100;
constraints.fill = GridBagConstraints.BOTH;
constraints.anchor = GridBagConstraints.CENTER;
constraints.insets = new Insets(10,10,10,10);
constraints.ipadx = 0;
constraints.ipady = 0;
gridBagLayout.setConstraints(JBClear, constraints);
JBClear.addActionListener(this);
// add to the pane
containerPane.add(JBClear);
///////////////// End Clear Chat History ////////////////////////
/////////////// Begin Save Chat History //////////////////////////
JBSave.setToolTipText("Save Chat History");
constraints.gridx = 8;
constraints.gridy = 10;
constraints.gridwidth = 2;
constraints.gridheight = 1;
constraints.weightx = 100;
constraints.weighty = 100;
constraints.fill = GridBagConstraints.BOTH;
constraints.anchor = GridBagConstraints.CENTER;
constraints.insets = new Insets(10,10,10,10);
constraints.ipadx = 0;
constraints.ipady = 0;
gridBagLayout.setConstraints(JBSave, constraints);
JBSave.addActionListener(this);
// add to the pane
containerPane.add(JBSave);
///////////////////// End Save Chat History /////////////////////
/////////////////// Begin Status Bar /////////////////////////////
constraints.gridx = 0;
constraints.gridy = 11;
constraints.gridwidth = 10;
constraints.gridheight = 1;
constraints.weightx = 100;
constraints.weighty = 50;
constraints.fill = GridBagConstraints.BOTH;
constraints.anchor = GridBagConstraints.CENTER;
constraints.insets = new Insets(0,10,5,0);
constraints.ipadx = 0;
constraints.ipady = 0;
gridBagLayout.setConstraints(statusBar, constraints);
// add to the pane
containerPane.add(statusBar);
////////////// End Status Bar ////////////////////////////
// set resizable to false
this.setResizable(false);
// pack the GUI
pack();
}
/**
* Deals with necessary menu click events
* @param event
*/
public void actionPerformed(ActionEvent event) {
Object source = event.getSource();
// Process Clear button event
if (source == JBClear){
textPaneHistory.setText(null);
statusBar.setText("Chat History Cleared");
}
// Process Save button event
if (source == JBSave){
// process only if there is data in history pane
if (textPaneHistory.getText().length() > 0){
// process location where to save the chat history file
JFileChooser chooser = new JFileChooser();
chooser.setMultiSelectionEnabled(false);
chooser.setAcceptAllFileFilterUsed(false);
FileNameExtensionFilter filter = new FileNameExtensionFilter("HTML Documents", "htm", "html");
chooser.setFileFilter(filter);
int option = chooser.showSaveDialog(ChatGUI.this);
if (option == JFileChooser.APPROVE_OPTION) {
// Set up document to be parsed as HTML
StyledDocument doc = (StyledDocument)textPaneHistory.getDocument();
HTMLEditorKit kit = new HTMLEditorKit();
BufferedOutputStream out;
try {
// add final file name and extension
String filePath = chooser.getSelectedFile().getAbsoluteFile() + ".html";
out = new BufferedOutputStream(new FileOutputStream(filePath));
// write out the HTML document
kit.write(out, doc, doc.getStartPosition().getOffset(), doc.getLength());
} catch (FileNotFoundException e) {
JOptionPane.showMessageDialog(ChatGUI.this,
"Application will now close. \n A restart may cure the error!\n\n"
+ e.getMessage(),
"Fatal Error",
JOptionPane.WARNING_MESSAGE, null);
System.exit(2);
} catch (IOException e){
JOptionPane.showMessageDialog(ChatGUI.this,
"Application will now close. \n A restart may cure the error!\n\n"
+ e.getMessage(),
"Fatal Error",
JOptionPane.WARNING_MESSAGE, null);
System.exit(3);
} catch (BadLocationException e){
JOptionPane.showMessageDialog(ChatGUI.this,
"Application will now close. \n A restart may cure the error!\n\n"
+ e.getMessage(),
"Fatal Error",
JOptionPane.WARNING_MESSAGE, null);
System.exit(4);
}
statusBar.setText("Chat History Saved");
}
}
}
}
/**
* Process return key for sending the message
*/
private class MyKeyAdapter extends KeyAdapter {
@Override
@SuppressWarnings("static-access")
public void keyPressed(KeyEvent ke) {
//DateTime dateTime = new DateTime();
//String nowdateTime = dateTime.getDateTime();
int kc = ke.getKeyCode();
if (kc == ke.VK_ENTER) {
try {
// Process only if there is data
if (textPaneHome.getText().length() > 0){
// Add message origin formatting
StyledDocument doc = (StyledDocument)textPaneHistory.getDocument();
Style style = doc.addStyle("HomeStyle", null);
StyleConstants.setBold(style, true);
String home = "Home [" + nowdateTime + "]: ";
doc.insertString(doc.getLength(), home, style);
StyleConstants.setBold(style, false);
doc.insertString(doc.getLength(), textPaneHome.getText() + "\n", style);
// update caret location
textPaneHistory.setCaretPosition(doc.getLength());
textPaneHome.setText(null);
statusBar.setText("Message Sent");
}
} catch (BadLocationException e) {
JOptionPane.showMessageDialog(ChatGUI.this,
"Application will now close. \n A restart may cure the error!\n\n"
+ e.getMessage(),
"Fatal Error",
JOptionPane.WARNING_MESSAGE, null);
System.exit(1);
}
ke.consume();
}
}
}
}
推荐答案
首先提出一些一般性意见：
Lots of general comments first:
a）发布代码时发布SSCCE。如果你不知道SSCCE是什么搜索论坛或网站。我们只有有限的时间来查看代码，300行是太多了。例如：
a) Post a SSCCE when you post code. If you don't know what a SSCCE is the search the forum or web. We only have limited time to look at code and 300 lines is way too much. For example:
- 代码设置对话框图标与问题无关，因为我们无法访问您的问题而无法运行资源文件
- 执行保存的代码无关紧要，因为这不是您要解决的问题
- 如前面提到的main（）方法缺失
b）使用正确的Java命名约定。变量名称以小写字符开头。 JBSave和JBClear不是标准名称，它使您的代码难以阅读。
b) use proper Java naming conventions. Variable names start with a lower case character. "JBSave" and "JBClear" are not standard names and it makes your code confusing to read.
c）我也同意Gridbaglayout很复杂，其他布局管理器（比如前面给出的BorderLayout方法更容易使用。具体来说，您对gridx和gridy的理解是不正确的。它们应该用于表示顺序的行和列位置。在你的情况下你应该使用（0,0），（0,1），（1,1），（2,1）。你将你的网格跳到了10. 10不反映相对大小。所以你缺少行，1,2,3,4,5,6,7 ...是的，它可能有用，但在阅读代码时理解起来很困惑。
c) I also agree the the Gridbaglayout is complicated and other layout managers (like the BorderLayout approach given earlier) are easier to use. In specific your understanding of the gridx and gridy is incorrect. They should be used to indicate "sequential" row and column positions. That is in your case you should use (0, 0), (0, 1), (1, 1), (2, 1). You jumped your gridy to 10. The 10 does not reflect a relative size. So you are missing rows, 1, 2, 3, 4, 5, 6, 7... Yes, it may work, but it is confusing to understand when reading the code.
d）不要使用KeyListener来处理文本窗格中的Enter键。 Swing旨在使用Key Bindings。有关详细信息，请阅读相同主题的Swing教程中的部分。
d) Don't use a KeyListener to handle the Enter key in the textpane. Swing was designed to use "Key Bindings". Read the section from the Swing tutorial on the same topic for more information.
最后，对代码的修复只是：
Finally the fix to your code is simply:
textPaneHome.setToolTipText("Home Chat Message Window");
// textPaneHome.setPreferredSize(new Dimension(200,50));
textPaneHome.addKeyListener(new MyKeyAdapter());
scrollPaneHomeText.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
scrollPaneHomeText.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
scrollPaneHomeText.setPreferredSize(new Dimension(200,50));
通常，您不应该设置添加到滚动窗格的组件的首选大小。
在这种情况下，当您将文本设置为null时，首选大小将重置为0，并且所有组件的布局似乎都将重做。
In general, you should never set the preferred size of a component added to a scrollpane. In this case when you set the text to null the preferred size gets reset to 0 and the layout of all the components appears to be redone.
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