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 WRAP_SYSTEM_OUT_METHOD_NAME = "wrapSystemOut";
053    private final static String WRAP_SYSTEM_ERR_METHOD_NAME = "wrapSystemErr";
054    private final static String SYSTEM_INSTALL_METHOD_NAME = "systemInstall";
055    private final static Class<?>[] ARGUMENT_TYPES = { PrintStream.class };
056
057    private final static String CONSOLE_APPENDER_WARNING_URL = CoreConstants.CODES_URL+"#slowConsole";
058
059    /**
060     * Sets the value of the <b>Target</b> option. Recognized values are
061     * "System.out" and "System.err". Any other value will be ignored.
062     */
063    public void setTarget(String value) {
064        ConsoleTarget t = ConsoleTarget.findByName(value.trim());
065        if (t == null) {
066            targetWarn(value);
067        } else {
068            target = t;
069        }
070    }
071
072    /**
073     * Returns the current value of the <b>target</b> property. The default value of
074     * the option is "System.out".
075     * <p>
076     * See also {@link #setTarget}.
077     */
078    public String getTarget() {
079        return target.getName();
080    }
081
082    private void targetWarn(String val) {
083        Status status = new WarnStatus("[" + val + "] should be one of " + Arrays.toString(ConsoleTarget.values()),
084                this);
085        status.add(new WarnStatus("Using previously set target, System.out by default.", this));
086        addStatus(status);
087    }
088
089    @Override
090    public void start() {
091        addInfo("NOTE: Writing to the console can be slow. Try to avoid logging to the ");
092        addInfo("console in production environments, especially in high volume systems.");
093        addInfo("See also "+CONSOLE_APPENDER_WARNING_URL);
094        OutputStream targetStream = target.getStream();
095        // enable jansi only if withJansi set to true
096        if (withJansi) {
097            targetStream = wrapWithJansi(targetStream);
098        }
099        setOutputStream(targetStream);
100        super.start();
101    }
102
103    private OutputStream wrapWithJansi(OutputStream targetStream) {
104        try {
105            addInfo("Enabling JANSI AnsiPrintStream for the console.");
106            ClassLoader classLoader = Loader.getClassLoaderOfObject(context);
107            Class<?> classObj = classLoader.loadClass(AnsiConsole_CLASS_NAME);
108
109            Method systemInstallMethod  = classObj.getMethod(SYSTEM_INSTALL_METHOD_NAME);
110            if(systemInstallMethod != null) {
111                systemInstallMethod.invoke(null);
112            }
113
114//            final Optional<Method> optSystemInstallMethod = Arrays.stream(classObj.getMethods())
115//                            .filter(m -> m.getName().equals(SYSTEM_INSTALL_METHOD_NAME))
116//                            .filter(m -> m.getParameters().length == 0)
117//                            .filter(m -> Modifier.isStatic(m.getModifiers()))
118//                            .findAny();
119//
120//            if (optSystemInstallMethod.isPresent()) {
121//                final Method systemInstallMethod = optSystemInstallMethod.orElseThrow(() -> new NoSuchElementException("No systemInstall method present"));
122//                systemInstallMethod.invoke(null);
123//            }
124
125            // check for JAnsi 2
126            String methodNameJansi2 = target == ConsoleTarget.SystemOut ? JANSI2_OUT_METHOD_NAME
127                    : JANSI2_ERR_METHOD_NAME;
128            final Optional<Method> optOutMethod = Arrays.stream(classObj.getMethods())
129                    .filter(m -> m.getName().equals(methodNameJansi2))
130                    .filter(m -> m.getParameters().length == 0)
131                    .filter(m -> Modifier.isStatic(m.getModifiers()))
132                    .filter(m -> PrintStream.class.isAssignableFrom(m.getReturnType()))
133                    .findAny();
134            if (optOutMethod.isPresent()) {
135                final Method outMethod = optOutMethod.orElseThrow(() -> new NoSuchElementException("No out/err method present"));
136                return (PrintStream) outMethod.invoke(null);
137            }
138
139            // JAnsi 1
140            String methodName = target == ConsoleTarget.SystemOut ? WRAP_SYSTEM_OUT_METHOD_NAME
141                    : WRAP_SYSTEM_ERR_METHOD_NAME;
142            Method method = classObj.getMethod(methodName, ARGUMENT_TYPES);
143            return (OutputStream) method.invoke(null, new PrintStream(targetStream));
144        } catch (Exception e) {
145            addWarn("Failed to create AnsiPrintStream. Falling back on the default stream.", e);
146        }
147        return targetStream;
148    }
149
150    /**
151     * @return whether to use JANSI or not.
152     */
153    public boolean isWithJansi() {
154        return withJansi;
155    }
156
157    /**
158     * If true, this appender will output to a stream provided by the JANSI library.
159     *
160     * @param withJansi whether to use JANSI or not.
161     * @since 1.0.5
162     */
163    public void setWithJansi(boolean withJansi) {
164        this.withJansi = withJansi;
165    }
166
167}