Log4j学习实践

新建一个初始化属性配置类：Log4jInit.
package com.longxin.entity;
import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.apache.log4j.PropertyConfigurator;

 

public class Log4jInit extends HttpServlet {

       public void init() {

              // 通过web.xml来动态取得配置文件

              String prefix = getServletContext().getRealPath("/");

              String file = getInitParameter("log4j-init-file");

              // 如果没有给出相应的配置文件，则不进行初始化

 

              if (file != null) {

                     PropertyConfigurator.configure(prefix + file);// （1）

              }

       }

 

       public void doGet(HttpServletRequest req, HttpServletResponse res) {

       }

 

}

 

 在web.xml中配置一个servlet,以保证在系统运行时初始化配置文件。

<servlet>

 <servlet-name>log4j</servlet-name>

 <servlet-class>com.longxin.entity.Log4jInit</servlet-class>

 <init-param>

 <param-name>log4j</param-name>

 <param-value>/WEB-INF/log4j.properties</param-value>

 </init-param> 

   </servlet>

新建配置文件：

#1 定义了两个输出端

log4j.rootLogger = INFO, A1,A2,A3

#2 定义A1输出到控制器，输出到控制台

log4j.appender.A1 = org.apache.log4j.ConsoleAppender

#3 定义A1的布局模式为PatternLayout

log4j.appender.A1.layout = org.apache.log4j.PatternLayout

#4 定义A1的输出格式

log4j.appender.A1.layout.ConversionPattern = %-4r [%t] %-5p %c - %m%n

#5 定义A2输出到文件

log4j.appender.A2 = org.apache.log4j.RollingFileAppender

#6 定义A2要输出到哪一个文件

log4j.appender.A2.File = c:\\example3.log

#7 定义A2的输出文件的最大长度

log4j.appender.A2.MaxFileSize = 1KB

#8 定义A2的备份文件数

log4j.appender.A2.MaxBackupIndex = 3

#9 定义A2的布局模式为PatternLayout

log4j.appender.A2.layout = org.apache.log4j.PatternLayout

#10 定义A2的输出格式

log4j.appender.A2.layout.ConversionPattern = %d{yyyy-MM-dd hh:mm:ss}:%p %t %c - %m%n

#11区 定义A3输出到数据库

log4j.appender.A3 = org.apache.log4j.jdbc.JDBCAppender

log4j.appender.A3.BufferSize = 40

log4j.appender.A3.Driver = com.microsoft.jdbc.sqlserver.SQLServerDriver

log4j.appender.A3.URL = jdbc:microsoft:sqlserver://zxl;databasename=hmsc;SelectMethod=Cursor

log4j.appender.A3.User =sa

log4j.appender.A3.Password =sa

log4j.appender.A3.layout = org.apache.log4j.PatternLayout

log4j.appender.A3.layout.ConversionPattern = INSERT INTO log4j (createDate, thread, priority, category, message) values(getdate(), '%t', '%-5p', '%c', '%m')

定义输出到数据库时，见表语句：

create table log4j(
logID int primary key identity,
message varchar(1024),
priority varchar(10),
milliseconds int,
category varchar(256),
thread varchar(100),
NDC varchar(256),
createDate datetime,
location varchar(256),
caller varchar(100),
method varchar(100),
filename varchar(100),
line int
)

应用程序中调用：

       static Logger logger = Logger.getLogger(SailingDateAction.class.getName());

 

logger.info("数据更新成功！");