java log4j.properties 中的这些属性是什么意思？
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What does these properties in log4j.properties mean?
提问by Anand
log4j.rootCategoryfeild in log4j.properties can have 4 different values namely:
log4j.rootCategorylog4j.properties 中的字段可以有 4 个不同的值，即：
DEBUG,WARN,INFO and ERROR. Can you tell me which is most suitable for what cases?
DEBUG,WARN,INFO and ERROR. 你能告诉我哪种最适合什么情况吗？
回答by bluish
From the least severe to the most one:
从最轻到最严重：
ALL < DEBUG < INFO < WARN < ERROR < FATAL < OFF
If you choose one of them log4j will print all messages of that type and of more severe type.
如果您选择其中之一，log4j 将打印该类型和更严重类型的所有消息。
Purposes:
目的：
ALL: prints all messages*DEBUG: debug messagesINFO: information that aren't problemsWARN: not error but something that could cause a future errorERROR: something went wrong, a problem that the application manages, the application could be stopped or not, usually must be reportedFATAL: an error that crashes the applicationOFF: prints no messages*
ALL: 打印所有消息*DEBUG: 调试信息INFO: 没有问题的信息WARN: 不是错误，而是可能导致未来错误的东西ERROR: 出现问题，应用程序管理的问题，应用程序可以停止或不停止，通常必须报告FATAL：导致应用程序崩溃的错误OFF: 不打印消息*
(*) these are only keywords; for these categories there are no methods all(msg)and off(msg), like we have error(msg)or debug(msg).
(*) 这些只是关键字；对于这些类别，没有方法all(msg)和off(msg)，就像我们有error(msg)或 一样debug(msg)。
Usually during development I set to ALLor DEBUG, while when deployed I set to INFOor WARN.
通常在开发过程中我设置为ALL或DEBUG，而在部署时我设置为INFO或WARN。
