Log4j日志文件存放到项目目录下

方法一：直接在log4j配置中写绝对路劲

方法二：新建一个ServletContextListener的实现类Log4jConfigListener，Log4jConfigListener做：

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String path = Environment.class.getResource("").getPath();  
String webAppPath = path.substring(0, path.toUpperCase().lastIndexOf("WEB-INF/")).replaceAll("%20", " ");  
System.setProperty("webapp",webAppPath + "logs/log.log");

在log4j配置中：

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log4j.appender.A2.File=${webapp}/logs/log.log

方法三（跟Spring集成）：在web.xml中配置

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<context-param>  
        <param-name>webAppRootKey</param-name>    
        <param-value>webapp.root</param-value>    
    </context-param>   
    <context-param>  
                <param-name>log4jConfigLocation</param-name>  
                <param-value>/WEB-INF/config/log4j.properties</param-value>  
    </context-param>   
    <context-param>  
                <param-name>log4jRefreshInterval</param-name>  
                <param-value>6000</param-value>  
    </context-param>  
    <listener>  
             <listener-class>org.springframework.web.util.Log4jConfigListener</listener-class>  
    </listener>

然后在log4j中用上述配置的webAppRootKey对应的值

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log4j.appender.file.File=${webapp.root}/WEB-INF/logs/log.log