# LogDemo

**Repository Path**: oopcoder/LogDemo

## Basic Information

- **Project Name**: LogDemo
- **Description**: No description available
- **Primary Language**: Java
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2026-05-10
- **Last Updated**: 2026-05-11

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# LogDemo
- [logback节点配置详解](https://www.cnblogs.com/DeepLearing/p/5663178.html)
- [logback的使用和logback.xml详解](https://www.cnblogs.com/warking/p/5710303.html)
- [logback 配置详解](https://www.jianshu.com/p/1ded57f6c4e3)
- [java 日志框架总结](https://www.cnblogs.com/baizhanshi/p/7911123.html)
- [log4j-over-slf4j与slf4j-log4j12共存stack overflow异常分析](https://www.cnblogs.com/pekkle/p/6813458.html)
- [Java之常用日志框架](https://www.jianshu.com/p/190c56429ec4)
- [JAVA日志框架概述](https://www.cnblogs.com/manayi/p/9570411.html)
- [slf4j与log4j、log4j2](https://blog.csdn.net/HarderXin/article/details/80422903)
- [Spring Boot（十）Logback和Log4j2集成与日志发展史](https://www.cnblogs.com/vipstone/p/9878862.html)

##### LoggingApplicationListener.java
```
/**
 * An {@link ApplicationListener} that configures the {@link LoggingSystem}. If the
 * environment contains a {@code logging.config} property it will be used to bootstrap the
 * logging system, otherwise a default configuration is used. Regardless, logging levels
 * will be customized if the environment contains {@code logging.level.*} entries and
 * logging groups can be defined with {@code logging.group}.
 **/
```

##### AbstractLoggingSystem.java
```
	@Override
	public void initialize(LoggingInitializationContext initializationContext, String configLocation, LogFile logFile) {
        // 如果配置了自定义 logging.config, 则使用自定义的配置文件，否则走默认流程
		if (StringUtils.hasLength(configLocation)) {
			initializeWithSpecificConfig(initializationContext, configLocation, logFile);
			return;
		}
		initializeWithConventions(initializationContext, logFile);
	}

	private void initializeWithSpecificConfig(LoggingInitializationContext initializationContext, String configLocation,
			LogFile logFile) {
		configLocation = SystemPropertyUtils.resolvePlaceholders(configLocation);
		loadConfiguration(initializationContext, configLocation, logFile);
	}

	private void initializeWithConventions(LoggingInitializationContext initializationContext, LogFile logFile) {
        // 获取日志本身支持的配置文件名
		String config = getSelfInitializationConfig();
        
		if (config != null && logFile == null) {
			// self initialization has occurred, reinitialize in case of property changes
            // 再次初始化
			reinitialize(initializationContext);
			return;
		}
        // 获取 *-spring.xml配置文件
		if (config == null) {
			config = getSpringInitializationConfig();
		}
		if (config != null) {
			loadConfiguration(initializationContext, config, logFile);
			return;
		}
		loadDefaults(initializationContext, logFile);

        // 优先级: 自定义 logging.config  > 框架本身支持的文件  > *-spring.xml  > springboot.jar 中提供的默认配置文件
        // 配置文件中的 属性 主要就是针对默认配置

        jar:file:/repository/org/springframework/boot/spring-boot/2.2.6.RELEASE/spring-boot-2.2.6.RELEASE.jar!
                 /org/springframework/boot/logging/log4j2/log4j2-file.xml
	}
```
##### Appender 里面拦截器分析

```
    UnsynchronizedAppenderBase.java

    public void doAppend(E eventObject) {
            .....
            // 返回 deny 则不打印
            if (getFilterChainDecision(eventObject) == FilterReply.DENY) {
                return;
            }

            // ok, we now invoke derived class' implementation of append
            this.append(eventObject);
            .....
    }

    FilterAttachableImpl.java

    /**
     * Loop through the filters in the list. As soon as a filter decides on
     * ACCEPT or DENY, then that value is returned. If all of the filters return
     * NEUTRAL, then NEUTRAL is returned.
     */
    public FilterReply getFilterChainDecision(E event) {

        final Filter<E>[] filterArrray = filterList.asTypedArray();
        final int len = filterArrray.length;

        for (int i = 0; i < len; i++) {
            final FilterReply r = filterArrray[i].decide(event);
            if (r == FilterReply.DENY || r == FilterReply.ACCEPT) {
                return r;
            }
        }

        // no decision
        return FilterReply.NEUTRAL;
    }
```
> 只要有拦截器返回 ACCEPT or DENY，就立马返回，不继续走拦截链了，类似于或的关系，所以特别注意不要在同一个拦截器中同时定义 ACCEPT or DENY，否则后面的拦截器就失效了，除非放最后面，或者有特殊需求

#### Springboot中 日志level的优先级
> 优先级：-Dlogging.level.root=ERROR  >  application.yml > logback-spring.xml

#### 在没有配置logback-spring.xml的前提下：

- 不配置logging.file.xxx，就打印到了控制台，级别为 INFO
- 如果只配置 logging.file.path=logs，logs目录下会有一个spring.log日志文件
- 如果只配置 logging.file.name=logs\\log.log，logs目录下就会有一个log.log文件
- 同时配置，以 logging.file.name 为准