Log4j日志文件输出为相对路径的解决方法

方法一：将日志文件输出到tomcat自身的日志文件夹logs中

Java代码 
# Set root category priority to info and its only appender to console.   
log4j.rootCategory=info,console,R  
#log4j.debug=true 
 
# console is set to be a ConsoleAppender using a PatternLayout.   
log4j.appender.console=org.apache.log4j.ConsoleAppender   
log4j.appender.console.Threshold=info   
log4j.appender.console.layout=org.apache.log4j.PatternLayout   
log4j.appender.console.layout.ConversionPattern=- %m%n  
 
# R is set to be a File appender using a PatternLayout.  
log4j.appender.R=org.apache.log4j.RollingFileAppender  
log4j.appender.R.Append=true 
log4j.appender.R.Threshold=info   
log4j.appender.R.MaxFileSize=1024KB   
log4j.appender.R.MaxBackupIndex=10 
log4j.appender.R.File=../logs/abc.log  
log4j.appender.R.layout=org.apache.log4j.PatternLayout  
log4j.appender.R.layout.ConversionPattern=%-d{yyyy-MM-dd HH\:mm\:ss} [%c]-[%p] %m%n 

# Set root category priority to info and its only appender to console.
log4j.rootCategory=info,console,R
#log4j.debug=true

# console is set to be a ConsoleAppender using a PatternLayout.
log4j.appender.console=org.apache.log4j.ConsoleAppender
log4j.appender.console.Threshold=info
log4j.appender.console.layout=org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern=- %m%n

# R is set to be a File appender using a PatternLayout.
log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.Append=true
log4j.appender.R.Threshold=info
log4j.appender.R.MaxFileSize=1024KB
log4j.appender.R.MaxBackupIndex=10
log4j.appender.R.File=../logs/abc.log
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%-d{yyyy-MM-dd HH\:mm\:ss} [%c]-[%p] %m%n



方法二：将日志文件输出到自己程序WEB-INF\logs目录中



1、在web.xml配置一个servlet

Xml代码 
<servlet> 
    <servlet-name>lo4jInit</servlet-name> 
    <servlet-class>com.linder.util.log4j.init.Lo4jInit</servlet-class> 
    <init-param> 
        <param-name>log4j_init_path</param-name> 
        <param-value>WEB-INF\classes\log4j.properties</param-value> 
    </init-param> 
    <init-param> 
        <param-name>log4j_file_path</param-name> 
        <param-value>WEB-INF\logs\</param-value> 
    </init-param> 
    <load-on-startup>0</load-on-startup> 
</servlet> 

<servlet>
<servlet-name>lo4jInit</servlet-name>
<servlet-class>com.linder.util.log4j.init.Lo4jInit</servlet-class>
<init-param>
<param-name>log4j_init_path</param-name>
<param-value>WEB-INF\classes\log4j.properties</param-value>
</init-param>
<init-param>
<param-name>log4j_file_path</param-name>
<param-value>WEB-INF\logs\</param-value>
</init-param>
<load-on-startup>0</load-on-startup>
</servlet>

2、编写一个初始化log4j的Servlet

Java代码 
package com.linder.util.log4j.init;  
 
import java.io.FileInputStream;  
import java.io.IOException;  
import java.util.Properties;  
 
import javax.servlet.ServletException;  
import javax.servlet.http.HttpServlet;  
import javax.servlet.http.HttpServletRequest;  
import javax.servlet.http.HttpServletResponse;  
 
import org.apache.log4j.Logger;  
import org.apache.log4j.PropertyConfigurator;  
 
 
public class Lo4jInit   extends HttpServlet {  
 
    /** 
     *  
     */ 
    private static final long serialVersionUID = 1L;  
    private static Logger logger=Logger.getLogger(Lo4jInit.class);  
      
    public void init(){  
        String path=this.getServletContext().getRealPath("/");  
        String file=this.getInitParameter("log4j_init_path");  
        String logFile=this.getInitParameter("log4j_file_path");  
        if(file!=null)  
        {  
            Properties prop = new Properties();   
            try{  
                prop.load(new FileInputStream(path+file)); //加载log4j.properties  
                prop.setProperty("log4j.appender.R.File", path+logFile+ prop.getProperty("log4j.appender.R.File")); //设置日志文件的输出路径  
                PropertyConfigurator.configure(prop); //加载配置项  
            }catch(Exception e)  
            {  
                logger.info("初始化log4j日志输入路径异常，请检查web.xml参数配置是否正常，异常发生在"+this.getClass().getName()+"类的public void init()方法，异常的愿意是："+e.getMessage(), e.fillInStackTrace());  
            }  
        }  
          
 
    }  
    protected void service(HttpServletRequest request, HttpServletResponse response)  
    throws ServletException, IOException {  
          
    }  
 
} 

package com.linder.util.log4j.init;

import java.io.FileInputStream;
import java.io.IOException;
import java.util.Properties;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.log4j.Logger;
import org.apache.log4j.PropertyConfigurator;


public class Lo4jInit   extends HttpServlet {

/**
*
*/
private static final long serialVersionUID = 1L;
private static Logger logger=Logger.getLogger(Lo4jInit.class);

public void init(){
String path=this.getServletContext().getRealPath("/");
String file=this.getInitParameter("log4j_init_path");
String logFile=this.getInitParameter("log4j_file_path");
if(file!=null)
{
Properties prop = new Properties();
try{
prop.load(new FileInputStream(path+file)); //加载log4j.properties
prop.setProperty("log4j.appender.R.File", path+logFile+ prop.getProperty("log4j.appender.R.File")); //设置日志文件的输出路径
PropertyConfigurator.configure(prop); //加载配置项
}catch(Exception e)
{
logger.info("初始化log4j日志输入路径异常，请检查web.xml参数配置是否正常，异常发生在"+this.getClass().getName()+"类的public void init()方法，异常的愿意是："+e.getMessage(), e.fillInStackTrace());
}
}


}
protected void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

}

}
3、log4j.properties的配置信息

Java代码 
# Set root category priority to info and its only appender to console.   
log4j.rootCategory=info,console,R  
#log4j.debug=true 
 
# console is set to be a ConsoleAppender using a PatternLayout.   
log4j.appender.console=org.apache.log4j.ConsoleAppender   
log4j.appender.console.Threshold=info   
log4j.appender.console.layout=org.apache.log4j.PatternLayout   
log4j.appender.console.layout.ConversionPattern=- %m%n  
 
# R is set to be a File appender using a PatternLayout.  
log4j.appender.R=org.apache.log4j.RollingFileAppender  
log4j.appender.R.Append=true 
log4j.appender.R.Threshold=info   
log4j.appender.R.MaxFileSize=1024KB   
log4j.appender.R.MaxBackupIndex=10 
log4j.appender.R.File=abc.log  
log4j.appender.R.layout=org.apache.log4j.PatternLayout  
log4j.appender.R.layout.ConversionPattern=%-d{yyyy-MM-dd HH\:mm\:ss} [%c]-[%p] %m%n