Source code

001/*
002 * Logback: the reliable, generic, fast and flexible logging framework.
003 * Copyright (C) 1999-2026, 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 v2.0 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;
028import ch.qos.logback.core.util.ReentryGuard;
029import ch.qos.logback.core.util.ReentryGuardFactory;
030
031/**
032 * ConsoleAppender appends log events to <code>System.out</code> or
033 * <code>System.err</code> using a layout specified by the user. The default
034 * target is <code>System.out</code>.
035 * <p>
036 * &nbsp;
037 * </p>
038 * For more information about this appender, please refer to the online manual
039 * at http://logback.qos.ch/manual/appenders.html#ConsoleAppender
040 *
041 * @author Ceki G&uuml;lc&uuml;
042 * @author Tom SH Liu
043 * @author Ruediger Dohna
044 */
045
046public class ConsoleAppender<E> extends OutputStreamAppender<E> {
047
048    protected ConsoleTarget target = ConsoleTarget.SystemOut;
049    protected boolean withJansi = false;
050
051
052    public final static String JLINE_JANSI_ANSI_CONSOLE_CLASS_NAME = "org.jline.jansi.AnsiConsole";
053    public final static String FUSESOURCE_JANSI_ANSI_CONSOLE_CLASS_NAME = "org.fusesource.jansi.AnsiConsole";
054
055    // Jansi was migrated from FuseSource (org.fusesource.jansi) to JLine (org.jline.jansi), which
056    // changed the package of AnsiConsole. Probe the JLine coordinates first, then fall back to the
057    // legacy FuseSource ones so that <withJansi> keeps working with both artifacts. See LOGBACK issue 1043.
058    private final static String[] ANSI_CONSOLE_CLASS_NAMES = { JLINE_JANSI_ANSI_CONSOLE_CLASS_NAME,
059            FUSESOURCE_JANSI_ANSI_CONSOLE_CLASS_NAME };
060
061    protected String preferredJansiClassName = null;
062
063    private final static String JANSI2_OUT_METHOD_NAME = "out";
064    private final static String JANSI2_ERR_METHOD_NAME = "err";
065    private final static String WRAP_SYSTEM_OUT_METHOD_NAME = "wrapSystemOut";
066    private final static String WRAP_SYSTEM_ERR_METHOD_NAME = "wrapSystemErr";
067    private final static String SYSTEM_INSTALL_METHOD_NAME = "systemInstall";
068    private final static Class<?>[] ARGUMENT_TYPES = { PrintStream.class };
069
070    private final static String CONSOLE_APPENDER_WARNING_URL = CoreConstants.CODES_URL+"#slowConsole";
071
072    /**
073     * Sets the value of the <b>Target</b> option. Recognized values are
074     * "System.out" and "System.err". Any other value will be ignored.
075     */
076    public void setTarget(String value) {
077        ConsoleTarget t = ConsoleTarget.findByName(value.trim());
078        if (t == null) {
079            targetWarn(value);
080        } else {
081            target = t;
082        }
083    }
084
085    /**
086     * Returns the current value of the <b>target</b> property. The default value of
087     * the option is "System.out".
088     * <p>
089     * See also {@link #setTarget}.
090     */
091    public String getTarget() {
092        return target.getName();
093    }
094
095    /**
096     *
097     * @return the preferred Jansi class name
098     */
099    public String getPreferredJansiClassName() {
100        return preferredJansiClassName;
101    }
102
103    /**
104     * It allows to force Jansi class name used for probing.
105     *
106     * <p>Used for testing purposes.</p>
107     * <p>Valid values are {@link #JLINE_JANSI_ANSI_CONSOLE_CLASS_NAME} and
108     * {@link #FUSESOURCE_JANSI_ANSI_CONSOLE_CLASS_NAME}.</p>
109     *
110     * @param preferredJansiClassName the preferred Jansi class name
111     * @since 1.6.1
112     */
113    public void setPreferredJansiClassName(String preferredJansiClassName) {
114        this.preferredJansiClassName = preferredJansiClassName;
115    }
116
117    private boolean isValidPreferredJansiClassName(String className) {
118        return JLINE_JANSI_ANSI_CONSOLE_CLASS_NAME.equals(className)
119                || FUSESOURCE_JANSI_ANSI_CONSOLE_CLASS_NAME.equals(className);
120    }
121
122    private void preferredJansiClassNameWarn(String val) {
123        Status status = new WarnStatus(
124                "[" + val + "] should be one of " + Arrays.toString(ANSI_CONSOLE_CLASS_NAMES), this);
125        status.add(new WarnStatus("Ignoring preferredJansiClassName, using default probing order.", this));
126        addStatus(status);
127    }
128
129    private void targetWarn(String val) {
130        Status status = new WarnStatus("[" + val + "] should be one of " + Arrays.toString(ConsoleTarget.values()),
131                this);
132        status.add(new WarnStatus("Using previously set target, System.out by default.", this));
133        addStatus(status);
134    }
135
136    @Override
137    public void start() {
138        addInfo("NOTE: Writing to the console can be slow. Try to avoid logging to the ");
139        addInfo("console in production environments, especially in high volume systems.");
140        addInfo("See also "+CONSOLE_APPENDER_WARNING_URL);
141        OutputStream targetStream = target.getStream();
142        // enable jansi only if withJansi set to true
143        if (withJansi) {
144            targetStream = wrapWithJansi(targetStream);
145        }
146        setOutputStream(targetStream);
147        super.start();
148    }
149
150    /**
151     * Create a ThreadLocal ReentryGuard to prevent recursive appender invocations.
152     * @return a ReentryGuard instance of type {@link ReentryGuardFactory.GuardType#THREAD_LOCAL THREAD_LOCAL}.
153     */
154    protected ReentryGuard buildReentryGuard() {
155        return ReentryGuardFactory.makeGuard(ReentryGuardFactory.GuardType.THREAD_LOCAL);
156    }
157
158    private OutputStream wrapWithJansi(OutputStream targetStream) {
159        try {
160            addInfo("Enabling JANSI AnsiPrintStream for the console.");
161            ClassLoader classLoader = Loader.getClassLoaderOfObject(context);
162            Class<?> classObj = loadAnsiConsoleClass(classLoader);
163
164            Method systemInstallMethod  = classObj.getMethod(SYSTEM_INSTALL_METHOD_NAME);
165            if(systemInstallMethod != null) {
166                systemInstallMethod.invoke(null);
167            }
168
169            // check for JAnsi 2
170            String methodNameJansi2 = target == ConsoleTarget.SystemOut ? JANSI2_OUT_METHOD_NAME
171                    : JANSI2_ERR_METHOD_NAME;
172            final Optional<Method> optOutMethod = Arrays.stream(classObj.getMethods())
173                    .filter(m -> m.getName().equals(methodNameJansi2))
174                    .filter(m -> m.getParameters().length == 0)
175                    .filter(m -> Modifier.isStatic(m.getModifiers()))
176                    .filter(m -> PrintStream.class.isAssignableFrom(m.getReturnType()))
177                    .findAny();
178            if (optOutMethod.isPresent()) {
179                final Method outMethod = optOutMethod.orElseThrow(() -> new NoSuchElementException("No out/err method present"));
180                return (PrintStream) outMethod.invoke(null);
181            }
182
183            // JAnsi 1
184            String methodName = target == ConsoleTarget.SystemOut ? WRAP_SYSTEM_OUT_METHOD_NAME
185                    : WRAP_SYSTEM_ERR_METHOD_NAME;
186            Method method = classObj.getMethod(methodName, ARGUMENT_TYPES);
187            return (OutputStream) method.invoke(null, new PrintStream(targetStream));
188        } catch (Exception e) {
189            addWarn("Failed to create AnsiPrintStream. Falling back on the default stream.", e);
190        }
191        return targetStream;
192    }
193
194    /**
195     * Loads the Jansi {@code AnsiConsole} class.
196     * <p>
197     * If {@link #preferredJansiClassName} is set to a valid value
198     * ({@link #JLINE_JANSI_ANSI_CONSOLE_CLASS_NAME} or {@link #FUSESOURCE_JANSI_ANSI_CONSOLE_CLASS_NAME}),
199     * that class is loaded. An invalid preferred value is reported and ignored.
200     * <p>
201     * If {@code preferredJansiClassName} is not set (or was invalid), candidates are probed in
202     * {@link #ANSI_CONSOLE_CLASS_NAMES} order (JLine's {@code org.jline.jansi} first, then the legacy
203     * FuseSource {@code org.fusesource.jansi}). This keeps {@code <withJansi>} working across the Jansi
204     * migration from FuseSource to JLine.
205     *
206     * @throws ClassNotFoundException if none of the candidate classes is available.
207     */
208    Class<?> loadAnsiConsoleClass(ClassLoader classLoader) throws ClassNotFoundException {
209        if (preferredJansiClassName != null) {
210            if (isValidPreferredJansiClassName(preferredJansiClassName)) {
211                return classLoader.loadClass(preferredJansiClassName);
212            } else {
213                preferredJansiClassNameWarn(preferredJansiClassName);
214            }
215        }
216        ClassNotFoundException lastException = null;
217        for (String className : ANSI_CONSOLE_CLASS_NAMES) {
218            try {
219                return classLoader.loadClass(className);
220            } catch (ClassNotFoundException e) {
221                lastException = e;
222            }
223        }
224        throw lastException;
225    }
226
227    /**
228     * @return whether to use JANSI or not.
229     */
230    public boolean isWithJansi() {
231        return withJansi;
232    }
233
234    /**
235     * If true, this appender will output to a stream provided by the JANSI library.
236     *
237     * @param withJansi whether to use JANSI or not.
238     * @since 1.0.5
239     */
240    public void setWithJansi(boolean withJansi) {
241        this.withJansi = withJansi;
242    }
243
244}