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本文主要研究一下springboot的logback配置
defaults.xml
org/springframework/boot/logging/logback/defaults.xml
代码语言：javascript复制<?xml version="1.0" encoding="UTF-8"?>
<!--
Default logback configuration provided for import
-->
<included>
<conversionRule conversionWord="clr" converterClass="org.springframework.boot.logging.logback.ColorConverter" />
<conversionRule conversionWord="wex" converterClass="org.springframework.boot.logging.logback.WhitespaceThrowableProxyConverter" />
<conversionRule conversionWord="wEx" converterClass="org.springframework.boot.logging.logback.ExtendedWhitespaceThrowableProxyConverter" />
<property name="CONSOLE_LOG_PATTERN" value="${CONSOLE_LOG_PATTERN:-%clr(%d{${LOG_DATEFORMAT_PATTERN:-yyyy-MM-dd HH:mm:ss.SSS}}){faint} %clr(${LOG_LEVEL_PATTERN:-%5p}) %clr(${PID:- }){magenta} %clr(---){faint} %clr([.15t]){faint} %clr(%-40.40logger{39}){cyan} %clr(:){faint} %m%n${LOG_EXCEPTION_CONVERSION_WORD:-%wEx}}"/>
<property name="FILE_LOG_PATTERN" value="${FILE_LOG_PATTERN:-%d{${LOG_DATEFORMAT_PATTERN:-yyyy-MM-dd HH:mm:ss.SSS}} ${LOG_LEVEL_PATTERN:-%5p} ${PID:- } --- [%t] %-40.40logger{39} : %m%n${LOG_EXCEPTION_CONVERSION_WORD:-%wEx}}"/>
<logger name="org.apache.catalina.startup.DigesterFactory" level="ERROR"/>
<logger name="org.apache.catalina.util.LifecycleBase" level="ERROR"/>
<logger name="org.apache.coyote.http11.Http11NioProtocol" level="WARN"/>
<logger name="org.apache.sshd.common.util.SecurityUtils" level="WARN"/>
<logger name="org.apache.tomcat.util.net.NioSelectorPool" level="WARN"/>
<logger name="org.eclipse.jetty.util.component.AbstractLifeCycle" level="ERROR"/>
<logger name="org.hibernate.validator.internal.util.Version" level="WARN"/>
<logger name="org.springframework.boot.actuate.endpoint.jmx" level="WARN"/>
</included>spring-boot包含了defaults.xml，它定义了一些conversionRule、CONSOLE_LOG_PATTERN、FILE_LOG_PATTERN变量以及一些logger
console-appender.xml
org/springframework/boot/logging/logback/console-appender.xml
代码语言：javascript复制<?xml version="1.0" encoding="UTF-8"?>
<!--
Console appender logback configuration provided for import, equivalent to the programmatic
initialization performed by Boot
-->
<included>
<appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>${CONSOLE_LOG_PATTERN}</pattern>
</encoder>
</appender>
</included>console-appender.xml定义了CONSOLE这个appender，其pattern取决于CONSOLE_LOG_PATTERN变量
file-appender.xml
org/springframework/boot/logging/logback/file-appender.xml
代码语言：javascript复制<?xml version="1.0" encoding="UTF-8"?>
<!--
File appender logback configuration provided for import, equivalent to the programmatic
initialization performed by Boot
-->
<included>
<appender name="FILE"
class="ch.qos.logback.core.rolling.RollingFileAppender">
<encoder>
<pattern>${FILE_LOG_PATTERN}</pattern>
</encoder>
<file>${LOG_FILE}</file>
<rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
<cleanHistoryOnStart>${LOG_FILE_CLEAN_HISTORY_ON_START:-false}</cleanHistoryOnStart>
<fileNamePattern>${ROLLING_FILE_NAME_PATTERN:-${LOG_FILE}.%d{yyyy-MM-dd}.%i.gz}</fileNamePattern>
<maxFileSize>${LOG_FILE_MAX_SIZE:-10MB}</maxFileSize>
<maxHistory>${LOG_FILE_MAX_HISTORY:-7}</maxHistory>
<totalSizeCap>${LOG_FILE_TOTAL_SIZE_CAP:-0}</totalSizeCap>
</rollingPolicy>
</appender>
</included>file-appender.xml定义了RollingFileAppender这个appender，其pattern取决于FILE_LOG_PATTERN，其file取决于LOG_FILE变量，rollingPolicy为SizeAndTimeBasedRollingPolicy，cleanHistoryOnStart默认为false，fileNamePattern默认为
${LOG_FILE}.%d{yyyy-MM-dd}.%i.gz}，maxFileSize默认为10MB，maxHistory默认为7，totalSizeCap默认为0
base.xml
org/springframework/boot/logging/logback/base.xml
代码语言：javascript复制<?xml version="1.0" encoding="UTF-8"?>
<!--
Base logback configuration provided for compatibility with Spring Boot 1.1
-->
<included>
<include resource="org/springframework/boot/logging/logback/defaults.xml" />
<property name="LOG_FILE" value="${LOG_FILE:-${LOG_PATH:-${LOG_TEMP:-${java.io.tmpdir:-/tmp}}}/spring.log}"/>
<include resource="org/springframework/boot/logging/logback/console-appender.xml" />
<include resource="org/springframework/boot/logging/logback/file-appender.xml" />
<root level="INFO">
<appender-ref ref="CONSOLE" />
<appender-ref ref="FILE" />
</root>
</included>base.xml引入了defaults.xml、console-appender.xml、file-appender.xml，它主要是定义了LOG_FILE路径，默认为
${java.io.tmpdir:-/tmp}}}/spring.log
logback.xml示例
代码语言：javascript复制 <?xml version="1.0" encoding="UTF-8"?>
<configuration>
<include resource="org/springframework/boot/logging/logback/defaults.xml"/>
<include resource="org/springframework/boot/logging/logback/console-appender.xml" />
<root level="INFO">
<appender-ref ref="CONSOLE" />
</root>
<logger name="org.springframework.web" level="DEBUG"/>
</configuration>loadDefaults
org/springframework/boot/logging/logback/LogbackLoggingSystem.java
代码语言：javascript复制 @Override
protected void loadDefaults(LoggingInitializationContext initializationContext, LogFile logFile) {
LoggerContext context = getLoggerContext();
stopAndReset(context);
boolean debug = Boolean.getBoolean("logback.debug");
if (debug) {
StatusListenerConfigHelper.addOnConsoleListenerInstance(context, new OnConsoleStatusListener());
}
LogbackConfigurator configurator = debug ? new DebugLogbackConfigurator(context)
: new LogbackConfigurator(context);
Environment environment = initializationContext.getEnvironment();
context.putProperty(LoggingSystemProperties.LOG_LEVEL_PATTERN,
environment.resolvePlaceholders("${logging.pattern.level:${LOG_LEVEL_PATTERN:%5p}}"));
context.putProperty(LoggingSystemProperties.LOG_DATEFORMAT_PATTERN, environment.resolvePlaceholders(
"${logging.pattern.dateformat:${LOG_DATEFORMAT_PATTERN:yyyy-MM-dd HH:mm:ss.SSS}}"));
context.putProperty(LoggingSystemProperties.ROLLING_FILE_NAME_PATTERN, environment
.resolvePlaceholders("${logging.pattern.rolling-file-name:${LOG_FILE}.%d{yyyy-MM-dd}.%i.gz}"));
new DefaultLogbackConfiguration(initializationContext, logFile).apply(configurator);
context.setPackagingDataEnabled(true);
}在没有logback.xml或者logback-spring.xml的时候，默认走的loadDefaults，它定义了LOG_LEVEL_PATTERN、LOG_DATEFORMAT_PATTERN、ROLLING_FILE_NAME_PATTERN，然后创建DefaultLogbackConfiguration并作用了LogbackConfigurator
DefaultLogbackConfiguration
org/springframework/boot/logging/logback/DefaultLogbackConfiguration.java
代码语言：javascript复制class DefaultLogbackConfiguration {
private static final String CONSOLE_LOG_PATTERN = "%clr(%d{${LOG_DATEFORMAT_PATTERN:-yyyy-MM-dd HH:mm:ss.SSS}}){faint} "
"%clr(${LOG_LEVEL_PATTERN:-%5p}) %clr(${PID:- }){magenta} %clr(---){faint} "
"%clr([.15t]){faint} %clr(%-40.40logger{39}){cyan} "
"%clr(:){faint} %m%n${LOG_EXCEPTION_CONVERSION_WORD:-%wEx}";
private static final String FILE_LOG_PATTERN = "%d{${LOG_DATEFORMAT_PATTERN:-yyyy-MM-dd HH:mm:ss.SSS}} "
"${LOG_LEVEL_PATTERN:-%5p} ${PID:- } --- [%t] %-40.40logger{39} : %m%n${LOG_EXCEPTION_CONVERSION_WORD:-%wEx}";
private static final DataSize MAX_FILE_SIZE = DataSize.ofMegabytes(10);
private static final Integer MAX_FILE_HISTORY = 7;
private final PropertyResolver patterns;
private final LogFile logFile;
DefaultLogbackConfiguration(LoggingInitializationContext initializationContext, LogFile logFile) {
this.patterns = getPatternsResolver(initializationContext.getEnvironment());
this.logFile = logFile;
}
void apply(LogbackConfigurator config) {
synchronized (config.getConfigurationLock()) {
base(config);
Appender<ILoggingEvent> consoleAppender = consoleAppender(config);
if (this.logFile != null) {
Appender<ILoggingEvent> fileAppender = fileAppender(config, this.logFile.toString());
config.root(Level.INFO, consoleAppender, fileAppender);
}
else {
config.root(Level.INFO, consoleAppender);
}
}
}
//......
} DefaultLogbackConfiguration类似于defaults.xml, console-appender.xml及file-appender.xml，不过它把相关配置直接写在代码里头省去xml解析，效率高一点；这里的apply代码显示执行base(config)，再是创建consoleAppender，再创建fileAppender
小结
spring-boot定义了defaults.xml提供了conversion rules、CONSOLE_LOG_PATTERN、FILE_LOG_PATTERN变量及一些常用logger；console-appender.xml则定义了使用CONSOLE_LOG_PATTERN的ConsoleAppender；file-appender.xml则定义了使用FILE_LOG_PATTERN及ROLLING_FILE_NAME_PATTERN的RollingFileAppender；而base.xml是兼容旧版springboot定义的，它集成了defaults.xml、console-appender.xml、file-appender.xml；而新版的话默认是通过DefaultLogbackConfiguration来定义base、consoleAppender以及fileAppender的，省去xml解析，效率更高一点。
