Getting all data in the consol and dumping it into a text file

[Lila Fowler]

Heya,

I'm trying to copy all the data from written to the console (incl errors, system.outs.. est) and write it to a text file. I know how to write it, but i have no clue how to get the data out of the actual console(Not the log file). Any ideas how this can be done?

Thanks

[Rok Štelcer]

Check the following link.

Hope it helps.

[Lila Fowler]

Thanks, but I'm a bit confused, if i'm correct that's basically creating a log file? We have a log file being created and updated constantly(deals with server side), but we also have a console(deals with client side) Some errors that appear in the console don't necessarily appear in the log file and visa versa. I only need to write the console if an exception occurs, i don't need to write it or constantly update it if that makes any sense.

Thanks

[Rok Štelcer]

Hm ... in that case I guess you only need to write err stream, right?
Try the following example: redirect.

Does this help?
If not, what about this one?

Perhaps I just don't understand what you're trying to do. ;)

[Lila Fowler]

example: redirect --> seems to be almost exactly what i need, although i need to write the complete console if an exception occurs kind of like copy and paste. The other thing i'm not really getting is where would i implement that code? (sorry for the stupid question ) But the console is a default function in java, what part is actaully accessing the original console data? Would

orgStream = System.out;

then contain the original data?

Thanks

[Rok Štelcer]

Regarding the second link ... I guess it's the answer to:

Lila Fowler wrote:Some errors that appear in the console don't necessarily appear in the log

When redirecting the console output to a file, you have to use "2>&1".
Otherwise, you'll only see standard output ...

Lili Fowler wrote:But the console is a default function in java, what part is actually accessing the original console data?Would

1. orgStream = System.out;

then contain the original data?

Well, printing to console output is indeed the default operation of stdin, stdout & stderr.
However with System.setXXX(...), you have the possibility to redirect it to e.g. a file.
So in above case it only contains the ref to the System.out, which is later used to restore the printing back to the console.


Regards,
Rok

[Campbell Ritchie]

No longer a "beginning" question. Moving thread.

[Lila Fowler]

Hi, sorry it took me so long to reply but I was moved to to other tickets.

Here is my code, but it still doesn't write the exception to the file, and the things that do write to the file don't display in the console. I need the .txt file to be a mirror image of the console. Any ideas?

Thanks.

Here is my current code.

  
import java.io.*;

public class CSSConsolRedirect
{
	
  public static void main(String[] args)  
  {   
    PrintStream outStream   = null;
    PrintStream errStream = null;
    PrintStream fileStream  = null;  
    try  
    {  
        outStream = System.out;
        errStream = System.err;
        fileStream = new PrintStream(new FileOutputStream("c:\\javaConsole.txt",true));  
        System.setErr(fileStream); 
        System.setOut(fileStream);
        outStream();
        System.err.println("CSSConsolRedirect err");//writes only to the file
        throw new RuntimeException("mwahahaha");//displays this exception in the consol but doesnt write it to the file

    }  
    catch (FileNotFoundException fnfEx)  
    {   
        fnfEx.printStackTrace();  
    }   
    finally  
    {  
        System.setOut(outStream); 
        System.setErr(errStream);
    }
  }
  
  public static void outStream()
  {
	  System.out.println("CSSConsolRedirect out");//writes only to the file
  }
} 

[Rob Spoor]

import java.io.*;

public class CSSConsolRedirect
{

  public static void main(String[] args)
  {
    PrintStream outStream   = null;
    PrintStream errStream = null;
    PrintStream fileStream  = null;
    try
    {
        outStream = System.out;
        errStream = System.err;
        fileStream = new PrintStream(new FileOutputStream("c:\\javaConsole.txt",true));
        System.setErr(fileStream);
        System.setOut(fileStream);
        outStream();
        System.err.println("CSSConsolRedirect err");//writes only to the file
        throw new RuntimeException("mwahahaha");//displays this exception in the consol but doesnt write it to the file

    }
    catch (FileNotFoundException fnfEx)
    {
        fnfEx.printStackTrace();
    }
    finally
    {
        System.setOut(outStream);
        System.setErr(errStream);
        System.err.println("hello"); // <- added line
    }
  }

  public static void outStream()
  {
      System.out.println("CSSConsolRedirect out");//writes only to the file
  }
}

That little hello is printed before the exception. That's because the control flow is like this:
- get a reference to the old streams (lines 3-4)
- set up the new streams (lines 5-7)
- test the redirect (lines 8-9)
- throw a RuntimeException (line 10)
- run the finally block to restore the old streams (lines 29-30)
- exit the main method with the RuntimeException (JVM internals)
- print the RuntimeException to the default, restored standard error stream (JVM internals)

If you want to write everything to your custom print stream simply don't call lines 29 and 30. If the JVM exits it will restore the default output and error streams and close all file handles opened from that Java application for you.

[Lila Fowler]

Thanks, that writes everything to my file as you said it would(took out lines 29 & 30), but i still need it in my console. Is there a way for the data to be printed in my both in the console as well as the .txt?
Thanks

[Rob Spoor]

You could create or find something called a "tee" output stream (named after the Unix tool "tee"). This basically duplicates data written to it. Apache Commons IO has such a class.

How it would work:

outStream = System.out;   
errStream = System.err;
OutputStream os = new FileOutputStream("c:\\javaConsole.txt", true); // only the file output stream
os = new TeeOutputStream(outStream, os); // create a TeeOutputStream that duplicates data to outStream and os
fileStream = new PrintStream(os);
System.setErr(fileStream);   
System.setOut(fileStream);

From now on everything written to either System.out or System.err will be written to both the original System.out and the file.

[Lila Fowler]

Thanks its now writing to both the file & the console, but the text has lost its color & functionality. eg if you had an exception it would be printed in red, similarly with System.err I understand its because you write it to the file and then to the console, but is it maybe possible to let it write to the console first & then to the file? Or a way to check the color and replace it when it is rewritten? I got it to display just red but not both black & red as it would originally write to the console.

Thanks

[Rob Spoor]

The console does not use colors. It is your IDE (Eclipse, Netbeans, ...) that adds these colors for System.err.

[Lila Fowler]

Ok, in that case i think i'm done. Thanks a million

[Rob Spoor]

You're welcome.