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.IOException;
017import java.io.OutputStream;
018import java.io.PrintStream;
019import java.lang.reflect.Method;
020import java.lang.reflect.Modifier;
021import java.util.Arrays;
022import java.util.NoSuchElementException;
023import java.util.Optional;
024
025import ch.qos.logback.core.joran.spi.ConsoleTarget;
026import ch.qos.logback.core.status.ErrorStatus;
027import ch.qos.logback.core.status.Status;
028import ch.qos.logback.core.status.WarnStatus;
029import ch.qos.logback.core.util.Loader;
030import ch.qos.logback.core.util.ReentryGuard;
031import ch.qos.logback.core.util.ReentryGuardFactory;
032
033/**
034 * ConsoleAppender appends log events to <code>System.out</code> or
035 * <code>System.err</code> using a layout specified by the user. The default
036 * target is <code>System.out</code>.
037 * <p>
038 * &nbsp;
039 * </p>
040 * For more information about this appender, please refer to the online manual
041 * at http://logback.qos.ch/manual/appenders.html#ConsoleAppender
042 * <p>
043 * This appender does not own the console streams it writes to. On stop it
044 * flushes those streams but does not close them, so process-wide stdout/stderr
045 * (and Jansi streams wrapping them) remain usable after reconfiguration.
046 * </p>
047 *
048 * @author Ceki G&uuml;lc&uuml;
049 * @author Tom SH Liu
050 * @author Ruediger Dohna
051 * @see <a href="https://github.com/qos-ch/logback/issues/1063">logback issue #1063</a>
052 */
053
054public class ConsoleAppender<E> extends OutputStreamAppender<E> {
055
056    protected ConsoleTarget target = ConsoleTarget.SystemOut;
057    protected boolean withJansi = false;
058
059
060    public final static String JLINE_JANSI_ANSI_CONSOLE_CLASS_NAME = "org.jline.jansi.AnsiConsole";
061    public final static String FUSESOURCE_JANSI_ANSI_CONSOLE_CLASS_NAME = "org.fusesource.jansi.AnsiConsole";
062
063    // Jansi was migrated from FuseSource (org.fusesource.jansi) to JLine (org.jline.jansi), which
064    // changed the package of AnsiConsole. Probe the JLine coordinates first, then fall back to the
065    // legacy FuseSource ones so that <withJansi> keeps working with both artifacts. See LOGBACK issue 1043.
066    private final static String[] ANSI_CONSOLE_CLASS_NAMES = { JLINE_JANSI_ANSI_CONSOLE_CLASS_NAME,
067            FUSESOURCE_JANSI_ANSI_CONSOLE_CLASS_NAME };
068
069    protected String preferredJansiClassName = null;
070
071    private final static String JANSI2_OUT_METHOD_NAME = "out";
072    private final static String JANSI2_ERR_METHOD_NAME = "err";
073    private final static String WRAP_SYSTEM_OUT_METHOD_NAME = "wrapSystemOut";
074    private final static String WRAP_SYSTEM_ERR_METHOD_NAME = "wrapSystemErr";
075    private final static String SYSTEM_INSTALL_METHOD_NAME = "systemInstall";
076    private final static Class<?>[] ARGUMENT_TYPES = { PrintStream.class };
077
078    private final static String CONSOLE_APPENDER_WARNING_URL = CoreConstants.CODES_URL+"#slowConsole";
079
080    /**
081     * Deprecation notice for {@link #setWithJansi(boolean)} / {@code <withJansi>}.
082     * {@link JansiConsoleAppender} is the recommended replacement.
083     */
084    static final String WITH_JANSI_DEPRECATED_MSG =
085            "ConsoleAppender.withJansi is deprecated and will be removed in a future release. "
086                    + "Use ch.qos.logback.core.JansiConsoleAppender instead.";
087
088    /**
089     * Sets the value of the <b>Target</b> option. Recognized values are
090     * "System.out" and "System.err". Any other value will be ignored.
091     */
092    public void setTarget(String value) {
093        ConsoleTarget t = ConsoleTarget.findByName(value.trim());
094        if (t == null) {
095            targetWarn(value);
096        } else {
097            target = t;
098        }
099    }
100
101    /**
102     * Returns the current value of the <b>target</b> property. The default value of
103     * the option is "System.out".
104     * <p>
105     * See also {@link #setTarget}.
106     */
107    public String getTarget() {
108        return target.getName();
109    }
110
111    /**
112     *
113     * @return the preferred Jansi class name
114     */
115    public String getPreferredJansiClassName() {
116        return preferredJansiClassName;
117    }
118
119    /**
120     * It allows to force Jansi class name used for probing.
121     *
122     * <p>Used for testing purposes.</p>
123     * <p>Valid values are {@link #JLINE_JANSI_ANSI_CONSOLE_CLASS_NAME} and
124     * {@link #FUSESOURCE_JANSI_ANSI_CONSOLE_CLASS_NAME}.</p>
125     *
126     * @param preferredJansiClassName the preferred Jansi class name
127     * @since 1.6.1
128     */
129    public void setPreferredJansiClassName(String preferredJansiClassName) {
130        this.preferredJansiClassName = preferredJansiClassName;
131    }
132
133    private boolean isValidPreferredJansiClassName(String className) {
134        return JLINE_JANSI_ANSI_CONSOLE_CLASS_NAME.equals(className)
135                || FUSESOURCE_JANSI_ANSI_CONSOLE_CLASS_NAME.equals(className);
136    }
137
138    private void preferredJansiClassNameWarn(String val) {
139        Status status = new WarnStatus(
140                "[" + val + "] should be one of " + Arrays.toString(ANSI_CONSOLE_CLASS_NAMES), this);
141        status.add(new WarnStatus("Ignoring preferredJansiClassName, using default probing order.", this));
142        addStatus(status);
143    }
144
145    private void targetWarn(String val) {
146        Status status = new WarnStatus("[" + val + "] should be one of " + Arrays.toString(ConsoleTarget.values()),
147                this);
148        status.add(new WarnStatus("Using previously set target, System.out by default.", this));
149        addStatus(status);
150    }
151
152    @Override
153    public void start() {
154        addInfo("NOTE: Writing to the console can be slow. Try to avoid logging to the ");
155        addInfo("console in production environments, especially in high volume systems.");
156        addInfo("See also "+CONSOLE_APPENDER_WARNING_URL);
157        OutputStream targetStream = wrapTarget(target.getStream());
158        setOutputStream(targetStream);
159        super.start();
160    }
161
162    /**
163     * Flush the console target without closing it.
164     * <p>
165     * {@link System#out}, {@link System#err}, and Jansi streams built on
166     * {@code FileDescriptor.out}/{@code err} are process-wide resources. Closing
167     * them from {@link OutputStreamAppender#stop()} would poison stdout for the
168     * rest of the JVM (see
169     * <a href="https://github.com/qos-ch/logback/issues/1063">issue #1063</a>).
170     * The non-Jansi {@link ConsoleTarget} streams already no-op on
171     * {@code close()}; this override keeps the same contract when Jansi is used.
172     * </p>
173     */
174    @Override
175    protected void closeOutputStream() {
176        if (getOutputStream() != null) {
177            try {
178                // write encoder footer while the stream is still attached
179                encoderClose();
180                getOutputStream().flush();
181            } catch (IOException e) {
182                addStatus(new ErrorStatus("Could not flush output stream for ConsoleAppender.", this, e));
183            }
184        }
185    }
186
187    /**
188     * Create a ThreadLocal ReentryGuard to prevent recursive appender invocations.
189     * @return a ReentryGuard instance of type {@link ReentryGuardFactory.GuardType#THREAD_LOCAL THREAD_LOCAL}.
190     */
191    protected ReentryGuard buildReentryGuard() {
192        return ReentryGuardFactory.makeGuard(ReentryGuardFactory.GuardType.THREAD_LOCAL);
193    }
194
195    /**
196     * Optionally wraps the raw console target stream before it is used for
197     * logging.
198     * <p>
199     * The default implementation applies the deprecated {@code withJansi}
200     * reflection path when {@link #withJansi} is true. Subclasses such as
201     * {@link JansiConsoleAppender} should override this method to supply an
202     * alternate stream (without relying on {@code withJansi}).
203     * </p>
204     *
205     * @param targetStream the raw stream for {@link #target}
206     * @return the stream to use as this appender's output stream
207     * @since 1.6.3
208     */
209    protected OutputStream wrapTarget(OutputStream targetStream) {
210        if (withJansi) {
211            return wrapWithJansi(targetStream);
212        } else {
213            return targetStream;
214        }
215    }
216
217    /**
218     * Wraps the console target stream with a Jansi ANSI-aware stream using
219     * reflection.
220     * <p>
221     * This path is <strong>deprecated</strong>. Prefer {@link JansiConsoleAppender},
222     * which overrides {@link #wrapTarget(OutputStream)} and calls
223     * {@code org.jline.jansi.AnsiConsole} directly.
224     * </p>
225     *
226     * @param targetStream the raw console target stream
227     * @return a Jansi-backed stream, or {@code targetStream} on failure
228     * @deprecated Use {@link JansiConsoleAppender} / override {@link #wrapTarget(OutputStream)}.
229     */
230    @Deprecated
231    protected OutputStream wrapWithJansi(OutputStream targetStream) {
232        addWarn(WITH_JANSI_DEPRECATED_MSG);
233        try {
234            addInfo("Enabling JANSI AnsiPrintStream for the console.");
235            ClassLoader classLoader = Loader.getClassLoaderOfObject(context);
236            Class<?> classObj = loadAnsiConsoleClass(classLoader);
237
238            Method systemInstallMethod  = classObj.getMethod(SYSTEM_INSTALL_METHOD_NAME);
239            if(systemInstallMethod != null) {
240                systemInstallMethod.invoke(null);
241            }
242
243            // check for JAnsi 2
244            String methodNameJansi2 = target == ConsoleTarget.SystemOut ? JANSI2_OUT_METHOD_NAME
245                    : JANSI2_ERR_METHOD_NAME;
246            final Optional<Method> optOutMethod = Arrays.stream(classObj.getMethods())
247                    .filter(m -> m.getName().equals(methodNameJansi2))
248                    .filter(m -> m.getParameters().length == 0)
249                    .filter(m -> Modifier.isStatic(m.getModifiers()))
250                    .filter(m -> PrintStream.class.isAssignableFrom(m.getReturnType()))
251                    .findAny();
252            if (optOutMethod.isPresent()) {
253                final Method outMethod = optOutMethod.orElseThrow(() -> new NoSuchElementException("No out/err method present"));
254                return (PrintStream) outMethod.invoke(null);
255            }
256
257            // JAnsi 1
258            String methodName = target == ConsoleTarget.SystemOut ? WRAP_SYSTEM_OUT_METHOD_NAME
259                    : WRAP_SYSTEM_ERR_METHOD_NAME;
260            Method method = classObj.getMethod(methodName, ARGUMENT_TYPES);
261            return (OutputStream) method.invoke(null, new PrintStream(targetStream));
262        } catch (Exception e) {
263            addWarn("Failed to create AnsiPrintStream. Falling back on the default stream.", e);
264        }
265        return targetStream;
266    }
267
268    /**
269     * Loads the Jansi {@code AnsiConsole} class.
270     * <p>
271     * If {@link #preferredJansiClassName} is set to a valid value
272     * ({@link #JLINE_JANSI_ANSI_CONSOLE_CLASS_NAME} or {@link #FUSESOURCE_JANSI_ANSI_CONSOLE_CLASS_NAME}),
273     * that class is loaded. An invalid preferred value is reported and ignored.
274     * <p>
275     * If {@code preferredJansiClassName} is not set (or was invalid), candidates are probed in
276     * {@link #ANSI_CONSOLE_CLASS_NAMES} order (JLine's {@code org.jline.jansi} first, then the legacy
277     * FuseSource {@code org.fusesource.jansi}). This keeps {@code <withJansi>} working across the Jansi
278     * migration from FuseSource to JLine.
279     *
280     * @throws ClassNotFoundException if none of the candidate classes is available.
281     */
282    Class<?> loadAnsiConsoleClass(ClassLoader classLoader) throws ClassNotFoundException {
283        if (preferredJansiClassName != null) {
284            if (isValidPreferredJansiClassName(preferredJansiClassName)) {
285                return classLoader.loadClass(preferredJansiClassName);
286            } else {
287                preferredJansiClassNameWarn(preferredJansiClassName);
288            }
289        }
290        ClassNotFoundException lastException = null;
291        for (String className : ANSI_CONSOLE_CLASS_NAMES) {
292            try {
293                return classLoader.loadClass(className);
294            } catch (ClassNotFoundException e) {
295                lastException = e;
296            }
297        }
298        throw lastException;
299    }
300
301    /**
302     * @return whether to use JANSI or not.
303     * @deprecated Use {@link JansiConsoleAppender} instead of {@code withJansi} on
304     *             {@link ConsoleAppender}.
305     */
306    @Deprecated
307    public boolean isWithJansi() {
308        return withJansi;
309    }
310
311    /**
312     * If true, this appender will output to a stream provided by the JANSI library
313     * via reflection.
314     * <p>
315     * This option is <strong>deprecated</strong>. Use {@link JansiConsoleAppender},
316     * which talks to {@code org.jline.jansi.AnsiConsole} directly, instead of
317     * {@code <withJansi>true</withJansi>} on a plain {@link ConsoleAppender}.
318     * </p>
319     *
320     * @param withJansi whether to use JANSI or not.
321     * @since 1.0.5
322     * @deprecated Use {@link JansiConsoleAppender} instead.
323     */
324    @Deprecated
325    public void setWithJansi(boolean withJansi) {
326        this.withJansi = withJansi;
327        if (withJansi) {
328            addWarn(WITH_JANSI_DEPRECATED_MSG);
329        }
330    }
331
332}