001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache license, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the license for the specific language governing permissions and
015 * limitations under the license.
016 */
017package org.apache.logging.log4j.core.appender;
018
019import java.io.IOException;
020import java.io.OutputStream;
021import java.io.PrintStream;
022import java.io.Serializable;
023import java.io.UnsupportedEncodingException;
024import java.lang.reflect.Constructor;
025import java.nio.charset.Charset;
026
027import org.apache.logging.log4j.core.Filter;
028import org.apache.logging.log4j.core.Layout;
029import org.apache.logging.log4j.core.config.plugins.Plugin;
030import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
031import org.apache.logging.log4j.core.config.plugins.PluginElement;
032import org.apache.logging.log4j.core.config.plugins.PluginFactory;
033import org.apache.logging.log4j.core.helpers.Booleans;
034import org.apache.logging.log4j.core.helpers.Loader;
035import org.apache.logging.log4j.core.layout.PatternLayout;
036import org.apache.logging.log4j.util.PropertiesUtil;
037
038/**
039 * ConsoleAppender appends log events to <code>System.out</code> or
040 * <code>System.err</code> using a layout specified by the user. The
041 * default target is <code>System.out</code>.
042 * @doubt accessing System.out or .err as a byte stream instead of a writer
043 *    bypasses the JVM's knowledge of the proper encoding. (RG) Encoding
044 * is handled within the Layout. Typically, a Layout will generate a String
045 * and then call getBytes which may use a configured encoding or the system
046 * default. OTOH, a Writer cannot print byte streams.
047 */
048@Plugin(name = "Console", category = "Core", elementType = "appender", printObject = true)
049public final class ConsoleAppender extends AbstractOutputStreamAppender<OutputStreamManager> {
050
051    private static final String JANSI_CLASS = "org.fusesource.jansi.WindowsAnsiOutputStream";
052    private static ConsoleManagerFactory factory = new ConsoleManagerFactory();
053
054    /**
055     * Enumeration of console destinations.
056     */
057    public enum Target {
058        /** Standard output. */
059        SYSTEM_OUT,
060        /** Standard error output. */
061        SYSTEM_ERR
062    }
063
064    private ConsoleAppender(final String name, final Layout<? extends Serializable> layout, final Filter filter,
065                            final OutputStreamManager manager,
066                            final boolean ignoreExceptions) {
067        super(name, layout, filter, ignoreExceptions, true, manager);
068    }
069
070    /**
071     * Create a Console Appender.
072     * @param layout The layout to use (required).
073     * @param filter The Filter or null.
074     * @param t The target ("SYSTEM_OUT" or "SYSTEM_ERR"). The default is "SYSTEM_OUT".
075     * @param follow If true will follow changes to the underlying output stream.
076     * @param name The name of the Appender (required).
077     * @param ignore If {@code "true"} (default) exceptions encountered when appending events are logged; otherwise
078     *               they are propagated to the caller.
079     * @return The ConsoleAppender.
080     */
081    @PluginFactory
082    public static ConsoleAppender createAppender(
083            @PluginElement("Layout") Layout<? extends Serializable> layout,
084            @PluginElement("Filters") final Filter filter,
085            @PluginAttribute("target") final String t,
086            @PluginAttribute("name") final String name,
087            @PluginAttribute("follow") final String follow,
088            @PluginAttribute("ignoreExceptions") final String ignore) {
089        if (name == null) {
090            LOGGER.error("No name provided for ConsoleAppender");
091            return null;
092        }
093        if (layout == null) {
094            layout = PatternLayout.createLayout(null, null, null, null, null, null);
095        }
096        final boolean isFollow = Boolean.parseBoolean(follow);
097        final boolean ignoreExceptions = Booleans.parseBoolean(ignore, true);
098        final Target target = t == null ? Target.SYSTEM_OUT : Target.valueOf(t);
099        return new ConsoleAppender(name, layout, filter, getManager(isFollow, target, layout), ignoreExceptions);
100    }
101
102    private static OutputStreamManager getManager(final boolean follow, final Target target, final Layout<? extends Serializable> layout) {
103        final String type = target.name();
104        final OutputStream os = getOutputStream(follow, target);
105        return OutputStreamManager.getManager(target.name() + "." + follow, new FactoryData(os, type, layout), factory);
106    }
107
108    private static OutputStream getOutputStream(final boolean follow, final Target target) {
109        final String enc = Charset.defaultCharset().name();
110        PrintStream printStream = null;
111        try {
112            printStream = target == Target.SYSTEM_OUT ?
113            follow ? new PrintStream(new SystemOutStream(), true, enc) : System.out :
114            follow ? new PrintStream(new SystemErrStream(), true, enc) : System.err;
115        } catch (final UnsupportedEncodingException ex) { // should never happen
116            throw new IllegalStateException("Unsupported default encoding " + enc, ex);
117        }
118        final PropertiesUtil propsUtil = PropertiesUtil.getProperties();
119        if (!propsUtil.getStringProperty("os.name").startsWith("Windows") ||
120            propsUtil.getBooleanProperty("log4j.skipJansi")) {
121            return printStream;
122        }
123        try {
124            final ClassLoader loader = Loader.getClassLoader();
125            // We type the parameter as a wildcard to avoid a hard reference to Jansi.
126            final Class<?> clazz = loader.loadClass(JANSI_CLASS);
127            final Constructor<?> constructor = clazz.getConstructor(OutputStream.class);
128            return (OutputStream) constructor.newInstance(printStream);
129        } catch (final ClassNotFoundException cnfe) {
130            LOGGER.debug("Jansi is not installed, cannot find {}", JANSI_CLASS);
131        } catch (final NoSuchMethodException nsme) {
132            LOGGER.warn("{} is missing the proper constructor", JANSI_CLASS);
133        } catch (final Exception ex) {
134            LOGGER.warn("Unable to instantiate {}", JANSI_CLASS);
135        }
136        return printStream;
137    }
138
139    /**
140     * An implementation of OutputStream that redirects to the current System.err.
141     */
142    private static class SystemErrStream extends OutputStream {
143        public SystemErrStream() {
144        }
145
146        @Override
147        public void close() {
148            // do not close sys err!
149        }
150
151        @Override
152        public void flush() {
153            System.err.flush();
154        }
155
156        @Override
157        public void write(final byte[] b) throws IOException {
158            System.err.write(b);
159        }
160
161        @Override
162        public void write(final byte[] b, final int off, final int len)
163            throws IOException {
164            System.err.write(b, off, len);
165        }
166
167        @Override
168        public void write(final int b) {
169            System.err.write(b);
170        }
171    }
172
173    /**
174     * An implementation of OutputStream that redirects to the current System.out.
175     */
176    private static class SystemOutStream extends OutputStream {
177        public SystemOutStream() {
178        }
179
180        @Override
181        public void close() {
182            // do not close sys out!
183        }
184
185        @Override
186        public void flush() {
187            System.out.flush();
188        }
189
190        @Override
191        public void write(final byte[] b) throws IOException {
192            System.out.write(b);
193        }
194
195        @Override
196        public void write(final byte[] b, final int off, final int len)
197            throws IOException {
198            System.out.write(b, off, len);
199        }
200
201        @Override
202        public void write(final int b) throws IOException {
203            System.out.write(b);
204        }
205    }
206
207    /**
208     * Data to pass to factory method.
209     */
210    private static class FactoryData {
211        private final OutputStream os;
212        private final String type;
213        private final Layout<? extends Serializable> layout;
214
215        /**
216         * Constructor.
217         * @param os The OutputStream.
218         * @param type The name of the target.
219         * @param layout A Serializable layout
220         */
221        public FactoryData(final OutputStream os, final String type, final Layout<? extends Serializable> layout) {
222            this.os = os;
223            this.type = type;
224            this.layout = layout;
225        }
226    }
227
228    /**
229     * Factory to create the Appender.
230     */
231    private static class ConsoleManagerFactory implements ManagerFactory<OutputStreamManager, FactoryData> {
232
233        /**
234         * Create an OutputStreamManager.
235         * @param name The name of the entity to manage.
236         * @param data The data required to create the entity.
237         * @return The OutputStreamManager
238         */
239        @Override
240        public OutputStreamManager createManager(final String name, final FactoryData data) {
241            return new OutputStreamManager(data.os, data.type, data.layout);
242        }
243    }
244
245}