001/**
002 * Logback: the reliable, generic, fast and flexible logging framework.
003 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
004 *
005 * This program and the accompanying materials are dual-licensed under
006 * either the terms of the Eclipse Public License v1.0 as published by
007 * the Eclipse Foundation
008 *
009 *   or (per the licensee's choosing)
010 *
011 * under the terms of the GNU Lesser General Public License version 2.1
012 * as published by the Free Software Foundation.
013 */
014package ch.qos.logback.core;
015
016import java.io.OutputStream;
017import java.io.PrintStream;
018import java.lang.reflect.Method;
019import java.lang.reflect.Modifier;
020import java.util.Arrays;
021import java.util.NoSuchElementException;
022import java.util.Optional;
023
024import ch.qos.logback.core.joran.spi.ConsoleTarget;
025import ch.qos.logback.core.status.Status;
026import ch.qos.logback.core.status.WarnStatus;
027import ch.qos.logback.core.util.Loader;
028
029/**
030 * ConsoleAppender appends log events to <code>System.out</code> or
031 * <code>System.err</code> using a layout specified by the user. The default
032 * target is <code>System.out</code>.
033 * <p>
034 * &nbsp;
035 * </p>
036 * For more information about this appender, please refer to the online manual
037 * at http://logback.qos.ch/manual/appenders.html#ConsoleAppender
038 *
039 * @author Ceki G&uuml;lc&uuml;
040 * @author Tom SH Liu
041 * @author Ruediger Dohna
042 */
043
044public class ConsoleAppender<E> extends OutputStreamAppender<E> {
045
046    protected ConsoleTarget target = ConsoleTarget.SystemOut;
047    protected boolean withJansi = false;
048
049    private final static String AnsiConsole_CLASS_NAME = "org.fusesource.jansi.AnsiConsole";
050    private final static String JANSI2_OUT_METHOD_NAME = "out";
051    private final static String JANSI2_ERR_METHOD_NAME = "err";
052    private final static String wrapSystemOut_METHOD_NAME = "wrapSystemOut";
053    private final static String wrapSystemErr_METHOD_NAME = "wrapSystemErr";
054    private final static Class<?>[] ARGUMENT_TYPES = { PrintStream.class };
055
056    private final static String CONSOLE_APPENDER_WARNING_URL = CoreConstants.CODES_URL+"#slowConsole";
057
058    /**
059     * Sets the value of the <b>Target</b> option. Recognized values are
060     * "System.out" and "System.err". Any other value will be ignored.
061     */
062    public void setTarget(String value) {
063        ConsoleTarget t = ConsoleTarget.findByName(value.trim());
064        if (t == null) {
065            targetWarn(value);
066        } else {
067            target = t;
068        }
069    }
070
071    /**
072     * Returns the current value of the <b>target</b> property. The default value of
073     * the option is "System.out".
074     * <p>
075     * See also {@link #setTarget}.
076     */
077    public String getTarget() {
078        return target.getName();
079    }
080
081    private void targetWarn(String val) {
082        Status status = new WarnStatus("[" + val + "] should be one of " + Arrays.toString(ConsoleTarget.values()),
083                this);
084        status.add(new WarnStatus("Using previously set target, System.out by default.", this));
085        addStatus(status);
086    }
087
088    @Override
089    public void start() {
090        addInfo("BEWARE: Writing to the console can be very slow. Avoid logging to the ");
091        addInfo("console in production environments, especially in high volume systems.");
092        addInfo("See also "+CONSOLE_APPENDER_WARNING_URL);
093        OutputStream targetStream = target.getStream();
094        // enable jansi only if withJansi set to true
095        if (withJansi) {
096            targetStream = wrapWithJansi(targetStream);
097        }
098        setOutputStream(targetStream);
099        super.start();
100    }
101
102    private OutputStream wrapWithJansi(OutputStream targetStream) {
103        try {
104            addInfo("Enabling JANSI AnsiPrintStream for the console.");
105            ClassLoader classLoader = Loader.getClassLoaderOfObject(context);
106            Class<?> classObj = classLoader.loadClass(AnsiConsole_CLASS_NAME);
107
108            // check for JAnsi 2
109            String methodNameJansi2 = target == ConsoleTarget.SystemOut ? JANSI2_OUT_METHOD_NAME
110                    : JANSI2_ERR_METHOD_NAME;
111            final Optional<Method> optOutMethod = Arrays.stream(classObj.getMethods())
112                    .filter(m -> m.getName().equals(methodNameJansi2))
113                    .filter(m -> m.getParameters().length == 0)
114                    .filter(m -> Modifier.isStatic(m.getModifiers()))
115                    .filter(m -> PrintStream.class.isAssignableFrom(m.getReturnType()))
116                    .findAny();
117            if (optOutMethod.isPresent()) {
118                final Method outMethod = optOutMethod.orElseThrow(() -> new NoSuchElementException("No value present"));
119                return (PrintStream) outMethod.invoke(null);
120            }
121
122            // JAnsi 1
123            String methodName = target == ConsoleTarget.SystemOut ? wrapSystemOut_METHOD_NAME
124                    : wrapSystemErr_METHOD_NAME;
125            Method method = classObj.getMethod(methodName, ARGUMENT_TYPES);
126            return (OutputStream) method.invoke(null, new PrintStream(targetStream));
127        } catch (Exception e) {
128            addWarn("Failed to create AnsiPrintStream. Falling back on the default stream.", e);
129        }
130        return targetStream;
131    }
132
133    /**
134     * @return whether to use JANSI or not.
135     */
136    public boolean isWithJansi() {
137        return withJansi;
138    }
139
140    /**
141     * If true, this appender will output to a stream provided by the JANSI library.
142     *
143     * @param withJansi whether to use JANSI or not.
144     * @since 1.0.5
145     */
146    public void setWithJansi(boolean withJansi) {
147        this.withJansi = withJansi;
148    }
149
150}