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88 lines
3.4 KiB
Markdown
88 lines
3.4 KiB
Markdown
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在这个案例里，动态修改应用的Logger Level。
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### 查找UserController的ClassLoader
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`sc -d com.example.demo.arthas.user.UserController | grep classLoaderHash`{{execute T2}}
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```bash
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$ sc -d com.example.demo.arthas.user.UserController | grep classLoaderHash
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classLoaderHash 1be6f5c3
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```
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注意hashcode是变化的，需要先查看当前的ClassLoader信息，提取对应ClassLoader的hashcode。
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如果你使用`-c`，你需要手动输入hashcode：`-c <hashcode>`
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```bash
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$ ognl -c 1be6f5c3 @com.example.demo.arthas.user.UserController@logger
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```
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对于只有唯一实例的ClassLoader可以通过`--classLoaderClass`指定class name，使用起来更加方便：
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```bash
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$ ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader @org.springframework.boot.SpringApplication@logger
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@Slf4jLocationAwareLog[
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FQCN=@String[org.apache.commons.logging.LogAdapter$Slf4jLocationAwareLog],
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name=@String[org.springframework.boot.SpringApplication],
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logger=@Logger[Logger[org.springframework.boot.SpringApplication]],
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]
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```
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`--classLoaderClass` 的值是ClassLoader的类名，只有匹配到唯一的ClassLoader实例时才能工作，目的是方便输入通用命令，而`-c <hashcode>`是动态变化的。
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### 用ognl获取logger
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`ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '@com.example.demo.arthas.user.UserController@logger'`{{execute T2}}
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```bash
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$ ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '@com.example.demo.arthas.user.UserController@logger'
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@Logger[
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serialVersionUID=@Long[5454405123156820674],
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FQCN=@String[ch.qos.logback.classic.Logger],
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name=@String[com.example.demo.arthas.user.UserController],
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level=null,
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effectiveLevelInt=@Integer[20000],
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parent=@Logger[Logger[com.example.demo.arthas.user]],
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childrenList=null,
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aai=null,
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additive=@Boolean[true],
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loggerContext=@LoggerContext[ch.qos.logback.classic.LoggerContext[default]],
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]
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```
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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。
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### 单独设置UserController的logger level
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`ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '@com.example.demo.arthas.user.UserController@logger.setLevel(@ch.qos.logback.classic.Level@DEBUG)'`{{execute T2}}
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再次获取`UserController@logger`，可以发现已经是`DEBUG`了：
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`ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '@com.example.demo.arthas.user.UserController@logger'`{{execute T2}}
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```bash
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$ ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '@com.example.demo.arthas.user.UserController@logger'
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@Logger[
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serialVersionUID=@Long[5454405123156820674],
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FQCN=@String[ch.qos.logback.classic.Logger],
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name=@String[com.example.demo.arthas.user.UserController],
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level=@Level[DEBUG],
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effectiveLevelInt=@Integer[10000],
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parent=@Logger[Logger[com.example.demo.arthas.user]],
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childrenList=null,
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aai=null,
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additive=@Boolean[true],
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loggerContext=@LoggerContext[ch.qos.logback.classic.LoggerContext[default]],
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]
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```
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### 修改logback的全局logger level
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通过获取`root` logger，可以修改全局的logger level：
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`ognl --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader '@org.slf4j.LoggerFactory@getLogger("root").setLevel(@ch.qos.logback.classic.Level@DEBUG)'`{{execute T2}}
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