Re: Trouble with custom InputStream being used by Readers
On 05/08/2008 19:57, Chase Preuninger allegedly wrote:
For some reason the following InputStream gives subclasses of Reader a
hard time because they seem to be unable to read the data. What is
wrong with my Stream. Ex. With the BufferedReader class when I call
the readLine() method it blocks forever even though there are a couple
of \n in the data that is being outputted. Also I know my stream
works because the read() method gives me an int which can be cast to a
char showing the text that the stream contains.
1. No need to make that class an InputStream -- make it a Reader;
2. A BufferedReader... buffers. He'll fill his buffer. If all to calls
to your InputStream block (because you only override read()), he won't
ever finish filling up if his internal buffer is larger than the input
(speculation).
3. Whatever JConsole is. (There isn't even an import statement for it --
or is it part of com.cpsoft.console)?
4. Heed Peter and Lew's advices.
5. The following is far from being perfect, but try if it works. As a
general rule, when writing InputStreams or Readers, always try to
override <int read(byte[], int, int)> or <int read(char[], int, int)>,
respectively.
<code imports_omitted="true">
public class ConsoleReader
extends Reader
{
private StringBuffer sbuf = new StringBuffer(1 << 5);
private JConsole con;
private final Object lock = new Object();
private boolean closed = false;
public ConsoleReader(JConsole c)
{
this.con = c;
synchronized(con)
{
EnterAction act = new EnterAction();
con.input.addActionListener(act);
con.enter.addActionListener(act);
}
}
/**
* Reads characters into a portion of an array. This method will block
* until some input is available, an I/O error occurs, or the end
of the
* stream is reached.
*
* @param cbuf Destination buffer
* @param off Offset at which to start storing characters
* @param len Maximum number of characters to read
*
* @return The number of characters read, or -1 if the end of the
* stream has been reached
*
* @exception IOException If an I/O error occurs
*/
public synchronized int read(char[] buf, int dest, int len)
throws IOException
{
if( closed ){
throw new IOException("Console closed");
}
while( sbuf.length() == 0 ){
synchronized (lock){
try{
lock.wait();
}
catch (InterruptedException x){
if( closed ){
return -1;
}
}
}
}
int rlen = Math.min(len, sbuf.length());
sbuf.getChars(0, rlen, buf, dest); //TODO: check dest + len <
buf.length?
sbuf.delete(0, rlen);
return rlen;
}
public void close(){
// 1. dispose of the console
// ...
closed = true;
// 2. notify any thread blocked on a read()
synchronized (lock){
lock.notifyAll();
}
}
private class EnterAction implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
synchronized(con) { //??
sbuf.append(con.input.getText()).append("\n");
}
synchronized (lock){
lock.notifyAll();
}
}
}
}
</code>
package com.cpsoft.console;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.*;
public class ConsoleInputStream extends InputStream
{
private StringBuffer buf = new StringBuffer();
private int pos = 0;
private JConsole con;
public ConsoleInputStream(JConsole c)
{
this.con = c;
synchronized(con)
{
EnterAction act = new EnterAction();
con.input.addActionListener(act);
con.enter.addActionListener(act);
}
}
public int read() throws IOException
{
while(buf.length() <= pos){}
return buf.charAt(pos++);
}
private class EnterAction implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
synchronized(con)
{
buf.append(con.input.getText() + "\n");
}
}
}
}
--
DF.