Add ConsoleAppender from log4j for diff visibility

1 files changed, 245 insertions, 0 deletions

diff --git a/src/main/java/org/apache/logging/log4j/core/appender/ConsoleAppender.java b/src/main/java/org/apache/logging/log4j/core/appender/ConsoleAppender.java
new file mode 100644
index 00000000..5629e0b1
--- /dev/null
+++ b/src/main/java/org/apache/logging/log4j/core/appender/ConsoleAppender.java
@@ -0,0 +1,245 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache license, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the license for the specific language governing permissions and
+ * limitations under the license.
+ */
+package org.apache.logging.log4j.core.appender;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.PrintStream;
+import java.io.Serializable;
+import java.io.UnsupportedEncodingException;
+import java.lang.reflect.Constructor;
+import java.nio.charset.Charset;
+
+import org.apache.logging.log4j.core.Filter;
+import org.apache.logging.log4j.core.Layout;
+import org.apache.logging.log4j.core.config.plugins.Plugin;
+import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
+import org.apache.logging.log4j.core.config.plugins.PluginElement;
+import org.apache.logging.log4j.core.config.plugins.PluginFactory;
+import org.apache.logging.log4j.core.helpers.Booleans;
+import org.apache.logging.log4j.core.helpers.Loader;
+import org.apache.logging.log4j.core.layout.PatternLayout;
+import org.apache.logging.log4j.util.PropertiesUtil;
+
+/**
+ * ConsoleAppender appends log events to <code>System.out</code> or
+ * <code>System.err</code> using a layout specified by the user. The
+ * default target is <code>System.out</code>.
+ * @doubt accessing System.out or .err as a byte stream instead of a writer
+ *    bypasses the JVM's knowledge of the proper encoding. (RG) Encoding
+ * is handled within the Layout. Typically, a Layout will generate a String
+ * and then call getBytes which may use a configured encoding or the system
+ * default. OTOH, a Writer cannot print byte streams.
+ */
+@Plugin(name = "Console", category = "Core", elementType = "appender", printObject = true)
+public final class ConsoleAppender extends AbstractOutputStreamAppender {
+
+    private static final String JANSI_CLASS = "org.fusesource.jansi.WindowsAnsiOutputStream";
+    private static ConsoleManagerFactory factory = new ConsoleManagerFactory();
+
+    /**
+     * Enumeration of console destinations.
+     */
+    public enum Target {
+        /** Standard output. */
+        SYSTEM_OUT,
+        /** Standard error output. */
+        SYSTEM_ERR
+    }
+
+    private ConsoleAppender(final String name, final Layout<? extends Serializable> layout, final Filter filter,
+                            final OutputStreamManager manager,
+                            final boolean ignoreExceptions) {
+        super(name, layout, filter, ignoreExceptions, true, manager);
+    }
+
+    /**
+     * Create a Console Appender.
+     * @param layout The layout to use (required).
+     * @param filter The Filter or null.
+     * @param t The target ("SYSTEM_OUT" or "SYSTEM_ERR"). The default is "SYSTEM_OUT".
+     * @param follow If true will follow changes to the underlying output stream.
+     * @param name The name of the Appender (required).
+     * @param ignore If {@code "true"} (default) exceptions encountered when appending events are logged; otherwise
+     *               they are propagated to the caller.
+     * @return The ConsoleAppender.
+     */
+    @PluginFactory
+    public static ConsoleAppender createAppender(
+            @PluginElement("Layout") Layout<? extends Serializable> layout,
+            @PluginElement("Filters") final Filter filter,
+            @PluginAttribute("target") final String t,
+            @PluginAttribute("name") final String name,
+            @PluginAttribute("follow") final String follow,
+            @PluginAttribute("ignoreExceptions") final String ignore) {
+        if (name == null) {
+            LOGGER.error("No name provided for ConsoleAppender");
+            return null;
+        }
+        if (layout == null) {
+            layout = PatternLayout.createLayout(null, null, null, null, null);
+        }
+        final boolean isFollow = Boolean.parseBoolean(follow);
+        final boolean ignoreExceptions = Booleans.parseBoolean(ignore, true);
+        final Target target = t == null ? Target.SYSTEM_OUT : Target.valueOf(t);
+        return new ConsoleAppender(name, layout, filter, getManager(isFollow, target, layout), ignoreExceptions);
+    }
+
+    private static OutputStreamManager getManager(final boolean follow, final Target target, final Layout<? extends Serializable> layout) {
+        final String type = target.name();
+        final OutputStream os = getOutputStream(follow, target);
+        return OutputStreamManager.getManager(target.name() + "." + follow, new FactoryData(os, type, layout), factory);
+    }
+
+    private static OutputStream getOutputStream(final boolean follow, final Target target) {
+        final String enc = Charset.defaultCharset().name();
+        PrintStream printStream = null;
+        try {
+            printStream = target == Target.SYSTEM_OUT ?
+                    follow ? new PrintStream(new SystemOutStream(), true, enc) : System.out :
+                    follow ? new PrintStream(new SystemErrStream(), true, enc) : System.err;
+        } catch (final UnsupportedEncodingException ex) { // should never happen
+            throw new IllegalStateException("Unsupported default encoding " + enc, ex);
+        }
+        final PropertiesUtil propsUtil = PropertiesUtil.getProperties();
+        if (!propsUtil.getStringProperty("os.name").startsWith("Windows") ||
+                propsUtil.getBooleanProperty("log4j.skipJansi")) {
+            return printStream;
+        }
+        try {
+            final ClassLoader loader = Loader.getClassLoader();
+            // We type the parameter as a wildcard to avoid a hard reference to Jansi.
+            final Class<?> clazz = loader.loadClass(JANSI_CLASS);
+            final Constructor<?> constructor = clazz.getConstructor(OutputStream.class);
+            return (OutputStream) constructor.newInstance(printStream);
+        } catch (final ClassNotFoundException cnfe) {
+            LOGGER.debug("Jansi is not installed, cannot find {}", JANSI_CLASS);
+        } catch (final NoSuchMethodException nsme) {
+            LOGGER.warn("{} is missing the proper constructor", JANSI_CLASS);
+        } catch (final Exception ex) {
+            LOGGER.warn("Unable to instantiate {}", JANSI_CLASS);
+        }
+        return printStream;
+    }
+
+    /**
+     * An implementation of OutputStream that redirects to the current System.err.
+     */
+    private static class SystemErrStream extends OutputStream {
+        public SystemErrStream() {
+        }
+
+        @Override
+        public void close() {
+            // do not close sys err!
+        }
+
+        @Override
+        public void flush() {
+            System.err.flush();
+        }
+
+        @Override
+        public void write(final byte[] b) throws IOException {
+            System.err.write(b);
+        }
+
+        @Override
+        public void write(final byte[] b, final int off, final int len)
+                throws IOException {
+            System.err.write(b, off, len);
+        }
+
+        @Override
+        public void write(final int b) {
+            System.err.write(b);
+        }
+    }
+
+    /**
+     * An implementation of OutputStream that redirects to the current System.out.
+     */
+    private static class SystemOutStream extends OutputStream {
+        public SystemOutStream() {
+        }
+
+        @Override
+        public void close() {
+            // do not close sys out!
+        }
+
+        @Override
+        public void flush() {
+            System.out.flush();
+        }
+
+        @Override
+        public void write(final byte[] b) throws IOException {
+            System.out.write(b);
+        }
+
+        @Override
+        public void write(final byte[] b, final int off, final int len)
+                throws IOException {
+            System.out.write(b, off, len);
+        }
+
+        @Override
+        public void write(final int b) throws IOException {
+            System.out.write(b);
+        }
+    }
+
+    /**
+     * Data to pass to factory method.
+     */
+    private static class FactoryData {
+        private final OutputStream os;
+        private final String type;
+        private final Layout<? extends Serializable> layout;
+
+        /**
+         * Constructor.
+         * @param os The OutputStream.
+         * @param type The name of the target.
+         * @param layout A Serializable layout
+         */
+        public FactoryData(final OutputStream os, final String type, final Layout<? extends Serializable> layout) {
+            this.os = os;
+            this.type = type;
+            this.layout = layout;
+        }
+    }
+
+    /**
+     * Factory to create the Appender.
+     */
+    private static class ConsoleManagerFactory implements ManagerFactory<OutputStreamManager, FactoryData> {
+
+        /**
+         * Create an OutputStreamManager.
+         * @param name The name of the entity to manage.
+         * @param data The data required to create the entity.
+         * @return The OutputStreamManager
+         */
+        @Override
+        public OutputStreamManager createManager(final String name, final FactoryData data) {
+            return new OutputStreamManager(data.os, data.type, data.layout);
+        }
+    }
+
+}