# log4j1 升級到 log4j2 的實戰紀錄
[前情提要](https://hackmd.io/zGqT5FsGRtSZKdDwmyVIoQ)
---
## 本篇還有加入slf4j

### Step1: 替換掉相關的jar檔
**原本log4j1 的相關jar檔**

**要替換的log4j2 和 slf4j的相關jar檔**
log4j-slf4j-impl 的jar檔是用來實現log4j2

### Step2: 修改呼叫logger相關的程式
**原本log4j1的 呼叫logger的寫法**

**改成用slf4j來呼叫logger的寫法**
(前人都用了slf4j但卻不知道為啥沒寫)

### Step3: 修改log4j.xml配置檔
**原本log4j1的相關設定檔**

**原本log4j1的xml配置**

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
	
    <appender name="CONSOLE" class="org.apache.log4j.ConsoleAppender">
        <param name="Encoding" value="UTF-8"/>
        <param name="Threshold" value="debug"/>
        <param name="Target" value="System.out"/>
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern"
                value="[%t] %d{HH:mm:ss} %-5p %-20C{1} L:%-4L - %m%n"/>
        </layout>
    </appender>
    
    <appender name="FILE" class="org.apache.log4j.DailyRollingFileAppender">
    	<param name="Encoding" value="UTF-8"/>
        <param name="File" value="log/nia_interview_srv.log" />
        <param name="DatePattern" value="'.'yyyyMMdd" />
        <param name="Append" value="true" />
        <param name="Threshold" value="DEBUG" />
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="[%-13.13t] %d{yyyyMMdd HH:mm:ss.SSS} %-5p %-20C{1} - %m%n" />
        </layout>
    </appender>
	
        
    <logger name="inspector.online">
        <level value="debug" />
        <appender-ref ref="FILE" />
    </logger>
	
    <logger name="org.apache.activemq">
    	<level value="info" />
    	<appender-ref ref="FILE" />
	</logger>
	
  	<logger name="org.springframework.transaction">
    	<level value="info" />
    	<appender-ref ref="FILE" />
	</logger>

    <root>
        <level value="error" />
        <appender-ref ref="CONSOLE" />
    </root>
</log4j:configuration>

---
**修改成log4j2的格式**

<?xml version="1.0" encoding="UTF-8" ?>

<configuration>
	<appenders>
		<Console name="CONSOLE" target="SYSTEM_OUT">
			<ThresholdFilter level="DEBUG" onMatch="ACCEPT"
				onMismatch="DENY" />
			<PatternLayout
				pattern="[%t] %d{HH:mm:ss} %-5p %-20C{1} L:%-4L - %m%n"
				charset="UTF-8" />
		</Console>

		<!-- 實現log4j1 的DailyRollingFileAppender -->
		<RollingFile name="FILE" fileName="log/nia_interview_srv.log"
			filePattern="log/%d{yyyyMMdd}_nia_interview_srv.log" append="true">
			<ThresholdFilter level="DEBUG" onMatch="ACCEPT"
				onMismatch="DENY" />
			<PatternLayout
			<PatternLayout
				pattern="[%-13.13t] %d{yyyyMMdd HH:mm:ss.SSS} %-5p %-20C{1} - %m%n"
				charset="UTF-8" />
			<Policies>
				<TimeBasedTriggeringPolicy interval="1" />
			</Policies>
		</RollingFile>

	</appenders>

	<loggers>
		<logger name="inspector.online" level="DEBUG"
			additivity="false">
			<appender-ref ref="FILE" />
		</logger>

		<logger name="org.apache.activemq" level="INFO"
			additivity="false">
			<appender-ref ref="FILE" />
		</logger>

		<logger name="org.springframework.transaction" level="INFO"
			additivity="false">
			<appender-ref ref="FILE" />
		</logger>

		<root level="ERROR">
			<appender-ref ref="CONSOLE" />
		</root>
	</loggers>
</configuration>

**Tip1:** log4j2 不再用log4j.dtd，所以刪掉log4j.dtd檔
**Tip2:** log4j2 沒有DailyRollingFileAppender，所以要用RollingFile 搭配<TimeBasedTriggeringPolicy interval="1" />
來實現
**Tip3:**<param name="Encoding" value="UTF-8"/>**改成在PatternLayout上面加上charset="UTF-8"**

---
### 修改完成

[log4j2配置檔參考資料 1: Pattern Layout詳細設置](https://www.jianshu.com/p/37ef7bc6d6eb)
[log4j2配置檔參考資料 2: log4j1和log4j2兩者的比較](https://blog.csdn.net/u012060033/article/details/104150519)
[log4j1 直接升 log4j2](https://blog.csdn.net/z69183787/article/details/74910675)

###### tags: `Java`