标签：一个 ISE mod over led 日志 ble 决定 gre
1.spring boot日志概述spring boot使用Commons Logging作为内部的日志系统，并且给Java Util Logging，Log4J2以及Logback都提供了默认的配置。
如果使用了spring boot的Starters，那么默认会使用Logback用于记录日志。
2.spring boot日志默认配置
我们启动一个空的spring-boot项目看一下控制台的日志
控制台的默认配置
logging.pattern.console=%clr(%d{${LOG_DATEFORMAT_PATTERN:-yyyy-MM-dd HH:mm:ss.SSS}}){faint} %clr(${LOG_LEVEL_PATTERN:-%5p}) %clr(${PID:- }){magenta} %clr(---){faint} %clr([%15.15t]){faint} %clr(%-40.40logger{39}){cyan} %clr(:){faint} %m%n${LOG_EXCEPTION_CONVERSION_WORD:-%wEx}
其中%clr为配置不同的颜色输出，支持的颜色有以下几种：
blue
cyan
faint
green
magenta
red
yellow
输出顺序分析：
1、日期和时间--精确到毫秒，并按照时间进行简单的排序，格式为：
%clr(%d{${LOG_DATEFORMAT_PATTERN:-yyyy-MM-dd HH:mm:ss.SSS}}){faint}
2、日志级别--ERROR,WARN,INFO,DEBUG,TRACE
%clr(${LOG_LEVEL_PATTERN:-%5p})
3、进程ID号
%clr(${PID:- })
4、日志内容，用"---"分隔符分开
%clr(---){faint}
5、线程名字--括在方括号中
%clr([%15.15t]){faint}
6、日志的名字--通常对应的是类名
%clr(%-40.40logger{39}){cyan}
注意：Logback没有FATAL级别（映射到ERROR）
不同日志级别对应的颜色如下
3.spring boot日志配置
可以通过application.properties或者application.yml查看所有配置
每个配置后面都有说明，就不一一赘述了。
4.spring boot日志实现原理
点击配置属性，可以进入LoggingApplicationListener这个类，
`/**
它实现了GenericApplicationListener接口，它默认定义了日志组DEFAULT_GROUP_LOGGERS和日志级别LOG_LEVEL_LOGGERS
private static final Map<String, List<String>> DEFAULT_GROUP_LOGGERS;
static {
MultiValueMap<String, String> loggers = new LinkedMultiValueMap<>();
loggers.add("web", "org.springframework.core.codec");
loggers.add("web", "org.springframework.http");
loggers.add("web", "org.springframework.web");
loggers.add("web", "org.springframework.boot.actuate.endpoint.web");
loggers.add("web",
"org.springframework.boot.web.servlet.ServletContextInitializerBeans");
loggers.add("sql", "org.springframework.jdbc.core");
loggers.add("sql", "org.hibernate.SQL");
DEFAULT_GROUP_LOGGERS = Collections.unmodifiableMap(loggers);
}
private static final Map<LogLevel, List<String>> LOG_LEVEL_LOGGERS;
static {
MultiValueMap<LogLevel, String> loggers = new LinkedMultiValueMap<>();
loggers.add(LogLevel.DEBUG, "sql");
loggers.add(LogLevel.DEBUG, "web");
loggers.add(LogLevel.DEBUG, "org.springframework.boot");
loggers.add(LogLevel.TRACE, "org.springframework");
loggers.add(LogLevel.TRACE, "org.apache.tomcat");
loggers.add(LogLevel.TRACE, "org.apache.catalina");
loggers.add(LogLevel.TRACE, "org.eclipse.jetty");
loggers.add(LogLevel.TRACE, "org.hibernate.tool.hbm2ddl");
LOG_LEVEL_LOGGERS = Collections.unmodifiableMap(loggers);
}你也可以自定义logging.level和logging.group,它们都是map结构。LoggingApplicationListener重写了onApplicationEvent方法，实现日志的打印
@Override
public void onApplicationEvent(ApplicationEvent event) {
if (event instanceof ApplicationStartingEvent) {
onApplicationStartingEvent((ApplicationStartingEvent) event); //1
}
else if (event instanceof ApplicationEnvironmentPreparedEvent) {
onApplicationEnvironmentPreparedEvent(
(ApplicationEnvironmentPreparedEvent) event); //2
}
else if (event instanceof ApplicationPreparedEvent) {
onApplicationPreparedEvent((ApplicationPreparedEvent) event); //3
}
else if (event instanceof ContextClosedEvent && ((ContextClosedEvent) event)
.getApplicationContext().getParent() == null) {
onContextClosedEvent(); //4
}
else if (event instanceof ApplicationFailedEvent) {
onApplicationFailedEvent(); //5
}
}
第一步：根据classloader里加载的依赖决定使用哪个日志系统？
主要实现有JavaLoggingSystem，Log4J2LoggingSystem，LogbackLoggingSystem
private void onApplicationStartingEvent(ApplicationStartingEvent event) {
this.loggingSystem = LoggingSystem
.get(event.getSpringApplication().getClassLoader());
this.loggingSystem.beforeInitialize();
}第二步：通过classpath，enviroment等获取参数初始化日志系统
/**
* Initialize the logging system according to preferences expressed through the
* {@link Environment} and the classpath.
* @param environment the environment
* @param classLoader the classloader
*/
protected void initialize(ConfigurableEnvironment environment,
ClassLoader classLoader) {
new LoggingSystemProperties(environment).apply();
LogFile logFile = LogFile.get(environment);
if (logFile != null) {
logFile.applyToSystemProperties();
}
initializeEarlyLoggingLevel(environment);
initializeSystem(environment, this.loggingSystem, logFile);
initializeFinalLoggingLevels(environment, this.loggingSystem);
registerShutdownHookIfNecessary(environment, this.loggingSystem);
}第三步：注册springBootLoggingSystem
private void onApplicationPreparedEvent(ApplicationPreparedEvent event) {
ConfigurableListableBeanFactory beanFactory = event.getApplicationContext()
.getBeanFactory();
if (!beanFactory.containsBean(LOGGING_SYSTEM_BEAN_NAME)) {
beanFactory.registerSingleton(LOGGING_SYSTEM_BEAN_NAME, this.loggingSystem);
}
}第四步和第五步：日志系统清洗
private void onContextClosedEvent() {
if (this.loggingSystem != null) {
this.loggingSystem.cleanUp();
}
}
private void onApplicationFailedEvent() {
if (this.loggingSystem != null) {
this.loggingSystem.cleanUp();
}
}5.自定义配置文件
日志系统 自定义配置文件
Logback
logback-spring.xml, logback-spring.groovy, logback.xml, or logback.groovy
Log4j2
log4j2-spring.xml or log4j2.xml
JDK (Java Util Logging)
logging.properties
6.总结
spring boot日志系统封装了logback，log4j2和java log，默认情况下使用java log，一旦使用各种starts，则默认使用Log4J2，也可以通过classpath来改变，pom.xml指定
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-logging</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-log4j</artifactId>
</dependency> 参考资料【2】https://www.jb51.net/article/133795.htm
让你的spring-boot应用日志随心所欲--spring boot日志深入分析
标签：一个 ISE mod over led 日志 ble 决定 gre
原文地址：https://blog.51cto.com/davidwang456/2410579
