TeePrintStream tees all PrintStream operations into a file, rather like the UNIX tee(1) command
/*
* Copyright (c) Ian F. Darwin, http://www.darwinsys.com/, 1996-2002.
* All rights reserved. Software written by Ian F. Darwin and others.
* $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* Java, the Duke mascot, and all variants of Sun's Java "steaming coffee
* cup" logo are trademarks of Sun Microsystems. Sun's, and James Gosling's,
* pioneering role in inventing and promulgating (and standardizing) the Java
* language and environment is gratefully acknowledged.
*
* The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
* inventing predecessor languages C and C++ is also gratefully acknowledged.
*/
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;
/**
* TeePrintStream tees all PrintStream operations into a file, rather like the
* UNIX tee(1) command. It is a PrintStream subclass. The expected usage would
* be something like the following:
*
* <PRE>
*
* ... TeePrintStream ts = new TeePrintStream(System.err, "err.log");
* System.setErr(ts); // ...lots of code that occasionally writes to
* System.err... ts.close(); ...
*
* <PRE>
*
* <P>
* I only override Constructors, the write(), check() and close() methods, since
* any of the print() or println() methods must go through these. Thanks to
* Svante Karlsson for help formulating this.
*
* @author Ian F. Darwin, http://www.darwinsys.com/
* @version $Id: TeePrintStream.java,v 1.5 2004/02/08 23:57:29 ian Exp $
*/
public class TeePrintStream extends PrintStream {
protected PrintStream parent;
protected String fileName;
/** A simple test case. */
public static void main(String[] args) throws IOException {
TeePrintStream ts = new TeePrintStream(System.err, "err.log", true);
System.setErr(ts);
System.err.println("An imitation error message");
ts.close();
}
/**
* Construct a TeePrintStream given an existing PrintStream, an opened
* OutputStream, and a boolean to control auto-flush. This is the main
* constructor, to which others delegate via "this".
*/
public TeePrintStream(PrintStream orig, OutputStream os, boolean flush)
throws IOException {
super(os, true);
fileName = "(opened Stream)";
parent = orig;
}
/**
* Construct a TeePrintStream given an existing PrintStream and an opened
* OutputStream.
*/
public TeePrintStream(PrintStream orig, OutputStream os) throws IOException {
this(orig, os, true);
}
/*
* Construct a TeePrintStream given an existing Stream and a filename.
*/
public TeePrintStream(PrintStream os, String fn) throws IOException {
this(os, fn, true);
}
/*
* Construct a TeePrintStream given an existing Stream, a filename, and a
* boolean to control the flush operation.
*/
public TeePrintStream(PrintStream orig, String fn, boolean flush)
throws IOException {
this(orig, new FileOutputStream(fn), flush);
}
/** Return true if either stream has an error. */
public boolean checkError() {
return parent.checkError() || super.checkError();
}
/** override write(). This is the actual "tee" operation. */
public void write(int x) {
parent.write(x); // "write once;
super.write(x); // write somewhere else."
}
/** override write(). This is the actual "tee" operation. */
public void write(byte[] x, int o, int l) {
parent.write(x, o, l); // "write once;
super.write(x, o, l); // write somewhere else."
}
/** Close both streams. */
public void close() {
parent.close();
super.close();
}
/** Flush both streams. */
public void flush() {
parent.flush();
super.flush();
}
}
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