Log4j2的Filters配置详解

╰半橙微兮° 2024-03-24 12:37 34阅读 0赞

> 官方配置文档：[https://logging.apache.org/log4j/2.x/manual/filters.html][https_logging.apache.org_log4j_2.x_manual_filters.html]

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## 日志级别 ##

level.共有8个级别，日志级别以及优先级排序: `OFF` > `FATAL` > `ERROR` > `WARN` > `INFO` > `DEBUG` > `TRACE` > `ALL`。

程序会打印`高于`或`等于`所设置级别的日志，设置的日志等级`越高`，打印出来的日志就`越少`。

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## Filter 特性 ##

A Filter will be called on one of its filter methods and will return a Result, which is an Enum that has one of 3 values - `ACCEPT（接受）`, `DENY（拒绝）` or `NEUTRAL（放行）`.

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## 分类 ##

### ThresholdFilter ###

This filter returns the onMatch result if the level in the LogEvent is `the same(==)` or `more specific than(>=)` the configured level and the onMismatch value otherwise.

#### Threshold Filter Parameters ####

<table> 
 <thead> 
  <tr> 
   <th align="left">Parameter Name</th> 
   <th align="left">Type</th> 
   <th align="left">Description</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td align="left">level</td> 
   <td align="left">String</td> 
   <td align="left">A valid Level name to match on.</td> 
  </tr> 
  <tr> 
   <td align="left">onMatch</td> 
   <td align="left">String</td> 
   <td align="left">Action to take when the filter matches. May be <code>ACCEPT</code>, <code>DENY</code> or <code>NEUTRAL</code>. <code>The default value is NEUTRAL</code>.</td> 
  </tr> 
  <tr> 
   <td align="left">onMismatch</td> 
   <td align="left">String</td> 
   <td align="left">Action to take when the filter does not match. May be <code>ACCEPT</code>, <code>DENY</code> or <code>NEUTRAL</code>. <code>The default value is DENY</code>.</td> 
  </tr> 
 </tbody> 
</table>

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#### 场景1：不加Filter场景，会受到`root level`控制 ####

[2023-04-02 12:01:01] [TRACE] [main] [LogTest.java:9] → [这是测试trace1]
    [2023-04-02 12:01:01] [DEBUG] [main] [LogTest.java:10] → [这是测试debug1]
    [2023-04-02 12:01:01] [INFO ] [main] [LogTest.java:11] → [这是测试info1]
    [2023-04-02 12:01:01] [WARN ] [main] [LogTest.java:12] → [这是测试warn1]
    [2023-04-02 12:01:01] [ERROR] [main] [LogTest.java:13] → [这是测试error1]
    [2023-04-02 12:01:01] [FATAL] [main] [LogTest.java:14] → [这是测试fatal1]

[2023-04-02 12:04:17] [ERROR] [main] [LogTest.java:13] → [这是测试error1]
    [2023-04-02 12:04:17] [FATAL] [main] [LogTest.java:14] → [这是测试fatal1]

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#### 场景2：加Filter过滤 `level >= ThresholdFilter level`的日志 ####

如果`ThresholdFilter level = INFO` 则打印 `FATAL, ERROR, WARN, INFO`；但是会受到`root level`影响。  
可以理解为：`root level`为第一道门，`ThresholdFilter level`为第二道门。

*  Demo1： `<root level="all">` ☞ 放行所有，`<ThresholdFilter level="info">`继续拦截

[2023-04-02 12:07:22] [INFO ] [main] [LogTest.java:11] → [这是测试info1]
    [2023-04-02 12:07:22] [WARN ] [main] [LogTest.java:12] → [这是测试warn1]
    [2023-04-02 12:07:22] [ERROR] [main] [LogTest.java:13] → [这是测试error1]
    [2023-04-02 12:07:22] [FATAL] [main] [LogTest.java:14] → [这是测试fatal1]

*  Demo2： `<root level="error">` ☞ `>=error`放行，`<ThresholdFilter level="info">` ☞ `>=info`放行，因为配置了`root level >= error` 导致到这里的都是`>=error`的日志

[2023-04-02 12:08:58] [ERROR] [main] [LogTest.java:13] → [这是测试error1]
    [2023-04-02 12:08:58] [FATAL] [main] [LogTest.java:14] → [这是测试fatal1]

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#### 场景3：Filter过滤`指定范围`的日志， ####

例如定制仅查看 `WARN` `INFO` 级别日志

[2023-04-02 12:39:31] [INFO ] [main] [LogTest.java:11] → [这是测试info1]
    [2023-04-02 12:39:31] [WARN ] [main] [LogTest.java:12] → [这是测试warn1]

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### TimeFilter ###

The time filter can be used to restrict filter to only a certain portion of the day.

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#### Time Filter Parameters ####

<table> 
 <thead> 
  <tr> 
   <th align="left">Parameter Name</th> 
   <th align="left">Type</th> 
   <th align="left">Description</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td align="left">start</td> 
   <td align="left">String</td> 
   <td align="left">A time in <code>HH:mm:ss format</code>.</td> 
  </tr> 
  <tr> 
   <td align="left">end</td> 
   <td align="left">String</td> 
   <td align="left">A time in <code>HH:mm:ss format</code>. Specifying an end time less than the start time will result in no log entries being written.<br>指定的结束时间小于开始时间将导致不写入日志项</td> 
  </tr> 
  <tr> 
   <td align="left">timezone</td> 
   <td align="left">String</td> 
   <td align="left">The <code>timezone</code> to use when comparing to the event timestamp.</td> 
  </tr> 
  <tr> 
   <td align="left">onMatch</td> 
   <td align="left">String</td> 
   <td align="left">Action to take when the filter matches. May be ACCEPT, DENY or NEUTRAL. <code>The default value is NEUTRAL</code>.</td> 
  </tr> 
  <tr> 
   <td align="left">onMismatch</td> 
   <td align="left">String</td> 
   <td align="left">Action to take when the filter does not match. May be ACCEPT, DENY or NEUTRAL. <code>The default value is DENY</code>.</td> 
  </tr> 
 </tbody> 
</table>

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#### 场景1：`from 5:00 to 5:30 am each day` using `the default timezone` ####

A sample configuration that only allows the event to be written by the appender `from 5:00 to 5:30 am each day` using `the default timezone`:

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[https_logging.apache.org_log4j_2.x_manual_filters.html]: https://logging.apache.org/log4j/2.x/manual/filters.html