问题
I have the code to this open source Message Console in java, but it simply won't compile. Can anyone see if it is operational using their IDE?
import java.io.*;
import java.awt.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.text.*;
/*
* Create a simple console to display text messages.
*
* Messages can be directed here from different sources. Each source can
* have its messages displayed in a different color.
*
* Messages can either be appended to the console or inserted as the first
* line of the console
*
* You can limit the number of lines to hold in the Document.
*/
public class MessageConsole
{
private JTextComponent textComponent;
private Document document;
private boolean isAppend;
private DocumentListener limitLinesListener;
public MessageConsole(JTextComponent textComponent)
{
this(textComponent, true);
}
/*
* Use the text component specified as a simply console to display
* text messages.
*
* The messages can either be appended to the end of the console or
* inserted as the first line of the console.
*/
public MessageConsole(JTextComponent textComponent, boolean isAppend)
{
this.textComponent = textComponent;
this.document = textComponent.getDocument();
this.isAppend = isAppend;
textComponent.setEditable( false );
}
/*
* Redirect the output from the standard output to the console
* using the default text color and null PrintStream
*/
public void redirectOut()
{
redirectOut(null, null);
}
/*
* Redirect the output from the standard output to the console
* using the specified color and PrintStream. When a PrintStream
* is specified the message will be added to the Document before
* it is also written to the PrintStream.
*/
public void redirectOut(Color textColor, PrintStream printStream)
{
ConsoleOutputStream cos = new ConsoleOutputStream(textColor, printStream);
System.setOut( new PrintStream(cos, true) );
}
/*
* Redirect the output from the standard error to the console
* using the default text color and null PrintStream
*/
public void redirectErr()
{
redirectErr(null, null);
}
/*
* Redirect the output from the standard error to the console
* using the specified color and PrintStream. When a PrintStream
* is specified the message will be added to the Document before
* it is also written to the PrintStream.
*/
public void redirectErr(Color textColor, PrintStream printStream)
{
ConsoleOutputStream cos = new ConsoleOutputStream(textColor, printStream);
System.setErr( new PrintStream(cos, true) );
}
/*
* To prevent memory from being used up you can control the number of
* lines to display in the console
*
* This number can be dynamically changed, but the console will only
* be updated the next time the Document is updated.
*/
public void setMessageLines(int lines)
{
if (limitLinesListener != null)
document.removeDocumentListener( limitLinesListener );
limitLinesListener = new LimitLinesDocumentListener(lines, isAppend);
document.addDocumentListener( limitLinesListener );
}
/*
* Class to intercept output from a PrintStream and add it to a Document.
* The output can optionally be redirected to a different PrintStream.
* The text displayed in the Document can be color coded to indicate
* the output source.
*/
class ConsoleOutputStream extends ByteArrayOutputStream
{
private SimpleAttributeSet attributes;
private PrintStream printStream;
private StringBuffer buffer = new StringBuffer(80);
private boolean isFirstLine;
/*
* Specify the option text color and PrintStream
*/
public ConsoleOutputStream(Color textColor, PrintStream printStream)
{
if (textColor != null)
{
attributes = new SimpleAttributeSet();
StyleConstants.setForeground(attributes, textColor);
}
this.printStream = printStream;
if (isAppend)
isFirstLine = true;
}
/*
* Override this method to intercept the output text. Each line of text
* output will actually involve invoking this method twice:
*
* a) for the actual text message
* b) for the newLine string
*
* The message will be treated differently depending on whether the line
* will be appended or inserted into the Document
*/
public void flush()
{
String message = toString();
if (message.length() == 0) return;
if (isAppend)
handleAppend(message);
else
handleInsert(message);
reset();
}
/*
* We don't want to have blank lines in the Document. The first line
* added will simply be the message. For additional lines it will be:
*
* newLine + message
*/
private void handleAppend(String message)
{
if (message.endsWith("\r")
|| message.endsWith("\n"))
{
buffer.append(message);
}
else
{
buffer.append(message);
clearBuffer();
}
}
/*
* We don't want to merge the new message with the existing message
* so the line will be inserted as:
*
* message + newLine
*/
private void handleInsert(String message)
{
buffer.append(message);
if (message.endsWith("\r")
|| message.endsWith("\n"))
{
clearBuffer();
}
}
/*
* The message and the newLine have been added to the buffer in the
* appropriate order so we can now update the Document and send the
* text to the optional PrintStream.
*/
private void clearBuffer()
{
// In case both the standard out and standard err are being redirected
// we need to insert a newline character for the first line only
if (isFirstLine && document.getLength() != 0)
{
buffer.insert(0, "\n");
}
isFirstLine = false;
String line = buffer.toString();
try
{
if (isAppend)
{
int offset = document.getLength();
document.insertString(offset, line, attributes);
textComponent.setCaretPosition( document.getLength() );
}
else
{
document.insertString(0, line, attributes);
textComponent.setCaretPosition( 0 );
}
}
catch (BadLocationException ble) {}
if (printStream != null)
{
printStream.print(line);
}
buffer.setLength(0);
}
}
}
Upon compiling, I received this error:
Error: limitLinesDocumentListener cannot be resolved to a type
回答1:
Import problem. You gotta have accesible the class or interface (I suppose class, because you have a simple constructor on the assignment: limitLinesListener = new LimitLinesDocumentListener(lines, isAppend);) LimitLinesDocumentListener. Simply that class is not found by the program. You need that in the same package of this file or you need to import that class.
回答2:
The blog post describing it made it pretty clear, IMO:
Finally, you need to decide if you need to limit the number of lines contained in the console. The MessageConsole will use my LimitLinesDocumentListener described in an earlier blog entry.
You can get LimitLinesDocumentListener from the earlier blog post.
When you've got both files, they compile together with no problems.
来源：https://stackoverflow.com/questions/10253933/message-console-java