大家好，又见面了，我是全栈君。

来源： case-ognl-update-logger-level

案例: 动态更新应用Logger Level

在这个案例里，动态修改应用的Logger Level。

查找UserController的ClassLoader

sc -d com.example.demo.arthas.user.UserController | grep classLoaderHash

$ sc -d com.example.demo.arthas.user.UserController | grep classLoaderHash
 classLoaderHash   1be6f5c3

用ognl获取logger

ognl –classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader ‘@com.example.demo.arthas.user.UserController@logger’

$ ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '@com.example.demo.arthas.user.UserController@logger'
@Logger[
    serialVersionUID=@Long[5454405123156820674],
    FQCN=@String[ch.qos.logback.classic.Logger],
    name=@String[com.example.demo.arthas.user.UserController],
    level=null,
    effectiveLevelInt=@Integer[20000],
    parent=@Logger[Logger[com.example.demo.arthas.user]],
    childrenList=null,
    aai=null,
    additive=@Boolean[true],
    loggerContext=@LoggerContext[ch.qos.logback.classic.LoggerContext[default]],
]

可以知道UserController@logger实际使用的是logback。可以看到level=null，则说明实际最终的level是从root logger里来的。

单独设置UserController的logger level

ognl –classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader ‘@com.example.demo.arthas.user.UserController@logger.setLevel(@ch.qos.logback.classic.Level@DEBUG)’

再次获取UserController@logger，可以发现已经是DEBUG了：

ognl –classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader ‘@com.example.demo.arthas.user.UserController@logger’

$ ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '@com.example.demo.arthas.user.UserController@logger'
@Logger[
    serialVersionUID=@Long[5454405123156820674],
    FQCN=@String[ch.qos.logback.classic.Logger],
    name=@String[com.example.demo.arthas.user.UserController],
    level=@Level[DEBUG],
    effectiveLevelInt=@Integer[10000],
    parent=@Logger[Logger[com.example.demo.arthas.user]],
    childrenList=null,
    aai=null,
    additive=@Boolean[true],
    loggerContext=@LoggerContext[ch.qos.logback.classic.LoggerContext[default]],
]

修改logback的全局logger level

ognl –classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader ‘@org.slf4j.LoggerFactory@getLogger(“root”).setLevel(@ch.qos.logback.classic.Level@DEBUG)’