java Web应用配置log4j日志记录

第一步：首先建立一个WEB工程，去log4j官网下log4j的JAR包导入到工程的lib目录下

第二步：在src目录下建一个log4j.properties 文件，文件命名可以由自己，只是记加载时候和这里名字一致就行；

log4j.properties 里边的内容如下：

### set log levels ###

log4j.rootLogger = debug,stdout,E

log4j.appender.stdout = org.apache.log4j.ConsoleAppender

log4j.appender.stdout.Target = System.out

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

log4j.appender.stdout.layout.ConversionPattern = %d{ABSOLUTE} %5p %c{1}:%L - %m%n

log4j.appender.E= org.apache.log4j.DailyRollingFileAppender

log4j.appender.E.File =${catalina.home}/logs/log_

log4j.appender.E.DatePattern=yyyy-MM-dd'.log'

log4j.appender.E.Threshold =DEBUG

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

log4j.appender.E.layout.ConversionPattern =%-d{yyyy-MM-dd HH\:mm\:ss}[%c] [%t\:%r] - [%p] %m%n

解释下几个常用的，其它的在详细的，请自己去网上查找资料：

stdout是一个日志记录配置，它的意思是把日志输出到控制台上，也就是这个配置属性--->log4j.appender.stdout.Target = System.out ,到时候到了生产上可以注解掉就可以了。

E是一个日志记录配置，它是把日志文件记录到文件中去，log4j.appender.E.File =${catalina.home}/logs/log_ 是放日志文件的路径，其中${catalina.home}是容器的路径

log4j.appender.E= org.apache.log4j.DailyRollingFileAppender 这个属性配置是一天产生一个新的日志文件（还有其它配置方式，这个是用的最多的）

log4j.appender.E.DatePattern=yyyy-MM-dd'.log' 这个属性是以时间为名字的文件日志，形式如下：

log_2011-06-26.log，log_2011-06-28.log，不过第一个生成的日志文件的名字是：log_

log4j.appender.E.layout.ConversionPattern =%-d{yyyy-MM-dd HH\:mm\:ss}[%c] [%t\:%r] - [%p] %m%n 这个是输出日志内容格式，详细情况请自己查阅资料；

log4j.appender.E.Threshold =DEBUG 这个是输出日志级别（意思是只输出比DEBUG级别高的日志信息）;

第三步：配置容器起动时候加载log4j配置文件：

建立一个servlet内容如下：

package com.tchzt.logTest;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import org.apache.log4j.PropertyConfigurator;

public class Log4jInit extends HttpServlet {

private static final long serialVersionUID = 1L;

public void destroy() {

super.destroy();

}

public Log4jInit() {

super();

}

/**

* Initialization of the servlet. <br>

*

* @throws ServletException if an error occurs

*/

public void init() throws ServletException {

String file =this.getInitParameter("log4j");//从web.xml配置读取，名字一定要和web.xml配置一致

if(file != null){

PropertyConfigurator.configure(file);

}

}

}

web.xml配置：

<servlet>

<servlet-name>Log4jInit</servlet-name>

<servlet-class>com.tchzt.logTest.Log4jInit</servlet-class>

<init-param>

<param-name>log4j</param-name>//这个是名字是下边路径配置的标识（好像KEY一样）

<param-value>/WEB-INF/classes/log4j.properties</param-value>//这是容器初始化时候加载log4j配置文件的路径（这好像一个value）;

</init-param>

</servlet>

好了基本上配置完了开始下测试了：

测试类：建立一个servlet内容如下：

package com.tchzt.logTest;

import java.io.IOException;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.apache.log4j.Logger;

public class Test extends HttpServlet {

private static final long serialVersionUID = 1L;

/**

* The doGet method of the servlet. <br>

*

* This method is called when a form has its tag value method equals to get.

*

* @param request the request send by the client to the server

* @param response the response send by the server to the client

* @throws ServletException if an error occurred

* @throws IOException if an error occurred

*/

public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

Logger logger = Logger.getLogger(Test.class.getName());

MyLog4j.getSomething();

System.out.println("================97987==============");

logger.info("日志信息开始!");

logger.info("日志信息结束!");

try {

Integer.parseInt("a");

} catch (NumberFormatException e) {

logger.error("解析数字出现异常",e);

e.printStackTrace();

}

}

/**

* The doPost method of the servlet. <br>

*

* This method is called when a form has its tag value method equals to post.

*

* @param request the request send by the client to the server

* @param response the response send by the server to the client

* @throws ServletException if an error occurred

* @throws IOException if an error occurred

*/

public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {

this.doGet(request, response);

}

}

这个servlet 的web.xml配置如下：

<servlet>

<servlet-name>Test</servlet-name>

<servlet-class>com.tchzt.logTest.Test</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>Test</servlet-name>

<url-pattern>/servlet/Test</url-pattern>

</servlet-mapping>

启动容器：输出URL：http://localhost:8080/Log4jWebTest/servlet/Test

第二次关闭容器，修改系统时间；在启动容器，最后生成日志文件如下：

log_；log_2011-06-26.log；log_2011-06-28.log；log_2011-06-30.log

内容这里选一个文件里的内容：

2011-06-30 21:59:28[test.jsp] [http-8080-2:0] - [ERROR] asdfasdf

2011-06-30 21:59:28[test.jsp] [http-8080-2:16] - [INFO] Test Logging in JSP

2011-06-30 21:59:28[test.jsp] [http-8080-2:16] - [FATAL] Test fatal logging in jsp page.

2011-06-30 21:59:28[test.jsp] [http-8080-2:16] - [ERROR] 解析数字出现异常

java.lang.NumberFormatException: For input string: "a"

at java.lang.NumberFormatException.forInputString(Unknown Source)

at java.lang.Integer.parseInt(Unknown Source)

at java.lang.Integer.parseInt(Unknown Source)

at org.apache.jsp.index_jsp._jspService(index_jsp.java:90)

at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)

at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)

at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:263)

at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)

at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:584)

at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)

at java.lang.Thread.run(Unknown Source)

2011-06-30 21:59:37[com.tchzt.logTest.MyLog4j] [http-8080-2:8641] - [ERROR] java.io.FileNotFoundException: F:\tt.txt (系统找不到指定的文件。)

2011-06-30 21:59:37[com.tchzt.logTest.Test] [http-8080-2:8656] - [INFO] 日志信息开始!

2011-06-30 21:59:37[com.tchzt.logTest.Test] [http-8080-2:8656] - [INFO] 日志信息结束!

2011-06-30 21:59:37[com.tchzt.logTest.Test] [http-8080-2:8656] - [ERROR] 解析数字出现异常

java.lang.NumberFormatException: For input string: "a"

at java.lang.NumberFormatException.forInputString(Unknown Source)

at java.lang.Integer.parseInt(Unknown Source)

at java.lang.Integer.parseInt(Unknown Source)

at com.tchzt.logTest.Test.doGet(Test.java:33)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:263)

at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)

at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:584)

at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)

at java.lang.Thread.run(Unknown Source)