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這篇要介紹在Spring MVC上加入Log4j2的功能

以下就介紹如何加入Log4j2的方法

1. 開啟你設置好的專案, 並在build.gradle下添加Log4j2的dependencies

主要有下列3個

    //log4j2
    compile 'org.apache.logging.log4j:log4j-core:2.5'
    compile 'org.apache.logging.log4j:log4j-api:2.5'
    compile 'org.apache.logging.log4j:log4j-web:2.5'

2. 接著創造一個log4j2.xml的設定檔

它的位置會在\WEB-INF內範例如下

<!DOCTYPE xml>
<Configuration status="TRACE">
    <Appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n" />
        </Console>
    </Appenders>
    <Loggers>
        <Root level="error">
            <AppenderRef ref="Console" />
        </Root>
    </Loggers>
</Configuration>

3. 然後在web.xml下

加入

  <!-- log4j2-begin -->
     <listener>
         <listener-class>org.apache.logging.log4j.web.Log4jServletContextListener</listener-class>
     </listener>
     <filter>
         <filter-name>log4jServletFilter</filter-name>
         <filter-class>org.apache.logging.log4j.web.Log4jServletFilter</filter-class>
     </filter>
     <filter-mapping>
         <filter-name>log4jServletFilter</filter-name>
         <url-pattern>/*</url-pattern>
         <dispatcher>REQUEST</dispatcher>
         <dispatcher>FORWARD</dispatcher>
         <dispatcher>INCLUDE</dispatcher>
         <dispatcher>ERROR</dispatcher>
     </filter-mapping>
     <!-- log4j2-end -->

4. 最後在要使用的地方

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

宣告Logger logger = LogManager.getLogger(LogManager.ROOT_LOGGER_NAME);

並使用logger.error("輸出字串");

如果在輸出看的到就代表成功了