systemloghandler.java

Tomcat 4.1与WebServer集成组件的源代码包.

/*
 * ====================================================================
 * 
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * 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.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:  
 *       "This product includes software developed by the 
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written 
 *    permission, please contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 APACHE SOFTWARE FOUNDATION OR
 * ITS 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */ 
package org.apache.tomcat.util.log;

import java.io.ByteArrayOutputStream;
import java.io.Writer;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.io.FileWriter;
import java.io.File;
import java.io.OutputStreamWriter;
import java.io.IOException;
import java.io.StringWriter;

import java.util.Hashtable;
import java.util.Stack;

/**
 * This helper class may be used to do sophisticated redirection of 
 * System.out and System.err on a per Thread basis.
 * 
 * A stack is implemented per Thread so that nested startCapture
 * and stopCapture can be used.
 *
 * @author Remy Maucherat
 * @author Glenn L. Nielsen
 */
public class SystemLogHandler extends PrintStream {


    // ----------------------------------------------------------- Constructors


    /**
     * Construct the handler to capture the output of the given steam.
     */
    public SystemLogHandler(PrintStream wrapped) {
        super(wrapped);
        out = wrapped;
    }


    // ----------------------------------------------------- Instance Variables


    /**
     * Wrapped PrintStream.
     */
    protected PrintStream out = null;


    /**
     * Thread <-> CaptureLog associations.
     */
    protected static Hashtable logs = new Hashtable();


    /**
     * Spare CaptureLog ready for reuse.
     */
    protected static Stack reuse = new Stack();


    // --------------------------------------------------------- Public Methods


    /**
     * Start capturing thread's output.
     */
    public static void startCapture() {
        CaptureLog log = null;
        if (!reuse.isEmpty()) {
            log = (CaptureLog)reuse.pop();
        } else {
            log = new CaptureLog();
        }
        Thread thread = Thread.currentThread();
        Stack stack = (Stack)logs.get(thread);
        if (stack == null) {
            stack = new Stack();
            logs.put(thread, stack);
        }
        stack.push(log);
    }


    /**
     * Stop capturing thread's output and return captured data as a String.
     */
    public static String stopCapture() {
        Stack stack = (Stack)logs.get(Thread.currentThread());
        if (stack == null || stack.isEmpty()) {
            return null;
        }
        CaptureLog log = (CaptureLog)stack.pop();
        if (log == null) {
            return null;
        }
        String capture = log.getCapture();
        log.reset();
        reuse.push(log);
        return capture;
    }


    // ------------------------------------------------------ Protected Methods


    /**
     * Find PrintStream to which the output must be written to.
     */
    protected PrintStream findStream() {
        Stack stack = (Stack)logs.get(Thread.currentThread());
        if (stack != null && !stack.isEmpty()) {
            CaptureLog log = (CaptureLog)stack.peek();
            if (log != null) {
                PrintStream ps = log.getStream();
                if (ps != null) {
                    return ps;
                }
            }
        }
        return out;
    }


    // ---------------------------------------------------- PrintStream Methods


    public void flush() {
        findStream().flush();
    }

    public void close() {
        findStream().close();
    }

    public boolean checkError() {
        return findStream().checkError();
    }

    protected void setError() {
        //findStream().setError();
    }

    public void write(int b) {
        findStream().write(b);
    }

    public void write(byte[] b)
        throws IOException {
        findStream().write(b);
    }

    public void write(byte[] buf, int off, int len) {
        findStream().write(buf, off, len);
    }

    public void print(boolean b) {
        findStream().print(b);
    }

    public void print(char c) {
        findStream().print(c);
    }

    public void print(int i) {
        findStream().print(i);
    }

    public void print(long l) {
        findStream().print(l);
    }

    public void print(float f) {
        findStream().print(f);
    }

    public void print(double d) {
        findStream().print(d);
    }

    public void print(char[] s) {
        findStream().print(s);
    }

    public void print(String s) {
        findStream().print(s);
    }

    public void print(Object obj) {
        findStream().print(obj);
    }

    public void println() {
        findStream().println();
    }

    public void println(boolean x) {
        findStream().println(x);
    }

    public void println(char x) {
        findStream().println(x);
    }

    public void println(int x) {
        findStream().println(x);
    }

    public void println(long x) {
        findStream().println(x);
    }

    public void println(float x) {
        findStream().println(x);
    }

    public void println(double x) {
        findStream().println(x);
    }

    public void println(char[] x) {
        findStream().println(x);
    }

    public void println(String x) {
        findStream().println(x);
    }

    public void println(Object x) {
        findStream().println(x);
    }

}