日志框架学习（5）— Spring中使用Log4j

这里要实现web项目中利用Spring来使用Log4j。

（1）导入Spring的包和日志包

（2）web.xml 文件

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
    id="WebApp_ID" version="3.0">
    <display-name>LogLearning_Springdisplay-name>
    <servlet>
        <servlet-name>Log4JTestServletservlet-name>
        <servlet-class>com.lpf.Log4JTestServletservlet-class>
    servlet>

    <servlet-mapping>
        <servlet-name>Log4JTestServletservlet-name>
        <url-pattern>/testurl-pattern>
    servlet-mapping>

    
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListenerlistener-class>
    listener>
    <context-param>
        <param-name>contextConfigLocationparam-name>
        <param-value>classpath:applicationContext.xmlparam-value>
    context-param>

    
    <context-param>
        <param-name>webAppRootKeyparam-name>
        <param-value>webapp.rootparam-value>
    context-param>

    <context-param>
        <param-name>log4jConfigLocationparam-name>
        <param-value>/WEB-INF/classes/log4j.propertiesparam-value>
    context-param>
    
    <context-param>
        <param-name>log4jRefreshIntervalparam-name>
        <param-value>3000param-value>
    context-param>
    <listener>
        <listener-class>org.springframework.web.util.Log4jConfigListenerlistener-class>
    listener>
web-app>

（3）applicationContext.xml

没有内容：

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="  
           http://www.springframework.org/schema/beans  
           http://www.springframework.org/schema/beans/spring-beans-3.2.xsd  
           http://www.springframework.org/schema/aop  
           http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
           http://www.springframework.org/schema/context  
           http://www.springframework.org/schema/context/spring-context-3.2.xsd">
beans>

（4）log4j.properties

 ### set log levels ###
log4j.rootLogger = debug,stdout,D,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 = [%-5p] %d{yyyy-MM-dd HH:mm:ss,SSS} method:%l%n%m%n

log4j.appender.D = org.apache.log4j.DailyRollingFileAppender
log4j.appender.D.File = E://logs/debug.log
log4j.appender.D.Append = true
log4j.appender.D.Threshold = DEBUG 
log4j.appender.D.layout = org.apache.log4j.PatternLayout
log4j.appender.D.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m%n

log4j.appender.E = org.apache.log4j.DailyRollingFileAppender
log4j.appender.E.File =E://logs/error.log 
log4j.appender.E.Append = true
log4j.appender.E.Threshold = ERROR 
log4j.appender.E.layout = org.apache.log4j.PatternLayout
log4j.appender.E.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m%n 

（5）这样日志就跟随Spring启动而启动了

程序一运行，就会自动把日志打印


error.log为空，因为它只打印error级别以上的信息

浏览器输入http://127.0.0.1/LogLearning_Spring/test

附：实验过程中发生的问题

message Error instantiating servlet class Log4JTestServlet

description The server encountered an internal error that prevented it from fulfilling this request.

exception

javax.servlet.ServletException: Error instantiating servlet class Log4JTestServlet
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023)
    org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
    java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    java.lang.Thread.run(Thread.java:745)


root cause

java.lang.ClassNotFoundException: Log4JTestServlet
    org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1714)
    org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1559)
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023)
    org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
    java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    java.lang.Thread.run(Thread.java:745)

这个问题找了半天也没找出原因，但是重新启动了一下电脑就好了。