[Log4J]一个只打Console并且设有最高级别的Appender
/* * Copyright 1999-2005 The Apache Software Foundation. * * Licensed 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. */ import java.io.IOException; import java.io.OutputStream; import org.apache.log4j.Layout; import org.apache.log4j.Level; import org.apache.log4j.WriterAppender; import org.apache.log4j.helpers.LogLog; import org.apache.log4j.spi.LoggingEvent; /** * 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>. * * @author Ceki Gülcü * @author Curt Arnold * @since 1.1 */ public class MyAppender extends WriterAppender { public static final String SYSTEM_OUT = "System.out"; public static final String SYSTEM_ERR = "System.err"; protected String target = SYSTEM_OUT; /** * Determines if the appender honors reassignments of System.out or * System.err made after configuration. */ private boolean follow = false; /** * Constructs an unconfigured appender. */ public MyAppender() { } /** * Creates a configured appender. * * @param layout * layout, may not be null. */ public MyAppender(Layout layout) { this(layout, SYSTEM_OUT); } /** * Creates a configured appender. * * @param layout * layout, may not be null. * @param targetStr * target, either "System.err" or "System.out". */ public MyAppender(Layout layout, String target) { setLayout(layout); setTarget(target); activateOptions(); } /** * Sets the value of the <b>Target</b> option. Recognized values are * "System.out" and "System.err". Any other value will be ignored. * */ public void setTarget(String value) { String v = value.trim(); if (SYSTEM_OUT.equalsIgnoreCase(v)) { target = SYSTEM_OUT; } else if (SYSTEM_ERR.equalsIgnoreCase(v)) { target = SYSTEM_ERR; } else { targetWarn(value); } } /** * Returns the current value of the <b>Target</b> property. The default * value of the option is "System.out". * * See also {@link #setTarget}. * */ public String getTarget() { return target; } /** * Sets whether the appender honors reassignments of System.out or * System.err made after configuration. * * @param newValue * if true, appender will use value of System.out or System.err * in force at the time when logging events are appended. * @since 1.2.13 */ public final void setFollow(final boolean newValue) { follow = newValue; } /** * Gets whether the appender honors reassignments of System.out or * System.err made after configuration. * * @return true if appender will use value of System.out or System.err in * force at the time when logging events are appended. * @since 1.2.13 */ public final boolean getFollow() { return follow; } @Override public void append(LoggingEvent event) { // Reminder: the nesting of calls is: // // doAppend() // - check threshold // - filter // - append(); // - checkEntryConditions(); // - subAppend(); //[yangyh] if (event.getLevel().isGreaterOrEqual(Level.WARN)) { return; } if (!checkEntryConditions()) { return; } subAppend(event); } void targetWarn(String val) { LogLog.warn("[" + val + "] should be System.out or System.err."); LogLog.warn("Using previously set target, System.out by default."); } /** * Prepares the appender for use. */ @Override public void activateOptions() { if (follow) { if (target.equals(SYSTEM_ERR)) { setWriter(createWriter(new SystemErrStream())); } else { setWriter(createWriter(new SystemOutStream())); } } else { if (target.equals(SYSTEM_ERR)) { setWriter(createWriter(System.err)); } else { setWriter(createWriter(System.out)); } } super.activateOptions(); } /** * {@inheritDoc} */ @Override protected final void closeWriter() { if (follow) { super.closeWriter(); } } /** * An implementation of OutputStream that redirects to the current * System.err. * */ private static class SystemErrStream extends OutputStream { public SystemErrStream() { } @Override public void close() { } @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) throws IOException { 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() { } @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); } } }
log4j.properties:
### set log levels ###
log4j.rootLogger = debug , stderr, D, A1
log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target = System.out
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern = %d{ABSOLUTE} %5p %c{1}:%L - %m%n
log4j.appender.stderr = org.apache.log4j.ConsoleAppender
log4j.appender.stderr.Target = System.err
log4j.appender.stderr.Threshold = WARN
log4j.appender.stderr.layout = org.apache.log4j.PatternLayout
log4j.appender.stderr.layout.ConversionPattern = %d{ABSOLUTE} %5p %c{1}:%L - %m%n
log4j.appender.A1 = com.baidu.tv.video.fetcher.log.MyAppender
log4j.appender.A1.Target = System.out
log4j.appender.A1.Threshold = DEBUG
log4j.appender.A1.layout = org.apache.log4j.PatternLayout
log4j.appender.A1.layout.ConversionPattern = %d{ABSOLUTE} %5p %c{1}:%L - %m%n
log4j.appender.D = org.apache.log4j.DailyRollingFileAppender
log4j.appender.D.File = logs/error.log
log4j.appender.D.Append = true
log4j.appender.D.Threshold = WARN
log4j.appender.D.layout = org.apache.log4j.PatternLayout
log4j.appender.D.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss} [ %t:%r ] - [ %p ] %m%n
貌似现在的Appender只有最低级别:Threshold
这里重写了WriterAppander的append方法
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