[java][log4j] Install Log4j & how to use it

1. 下載log4j的jar檔 (log4j.1.12.17.jar)

2. 放到C:\Users\1409035\workspace\NewsstandWS\web\WEB-INF\lib 底下

3. 新增一個log4j_WS.properites檔放到
   C:\Users\1409035\workspace\NewsstandWS\web\WEB-INF\properties 底下
   設定內容直接參考code

4. 新增 Log4JInitServlet.java 到
   C:\Users\1409035\workspace\NewsstandWS\src\java\com\ws\controller
   做為初始化用 

5. 修改 web.xml 新增如下
   
    Log4JInitServlet
    com.ws.controller.Log4JInitServlet
     
    log4j-properties-location
        /WEB-INF/properties/log4j_WS.properties
     
    1 
   

6. 使用範例
   final Logger log = Logger.getLogger(GetZinioDataJobs.class);
   log.info("orderBook info message");




參考:
http://www.programcreek.com/2009/06/a-simple-example-to-show-how-to-use-java-properties-file/ [^]
http://www.avajava.com/tutorials/lessons/how-do-i-initialize-log4j-in-a-web-application.html [^]
http://www.codejava.net/coding/how-to-initialize-log4j-for-java-web-application [^]
http://toyangel.pixnet.net/blog/post/32953401-eclipse-%E4%BD%BF%E7%94%A8-log4j-%E7%9A%84%E5%BF%AB%E9%80%9F%E8%A8%AD%E5%AE%9A [^]

簡單版:

log4j.properties
直接放到src/java下面

web.xml
也可拿掉上述所新添加的部分。


===========================================
原因:
tomcat 啟動時的順序-->
tomcat --> AP(newsstands) -->看底下web-inf 裡面的classes jar, 
因為log4j 已經有default , 且我又將 properties 命名為 logj4.properties
所以他default找的到這隻，
如果我不命名為 logj4.properties，
就要遵循 本篇一開始的步驟

============================

將log4j改為 大於 10M 就產生新的檔案

# A2 is set to be a file
# produce log record document every day
#log4j.appender.A2 = org.apache.log4j.FileAppender
log4j.appender.A2 = org.apache.log4j.RollingFileAppender
log4j.appender.A2.layout = org.apache.log4j.PatternLayout
log4j.appender.A2.layout.ConversionPattern = [%d{yyyy-MM-dd HH:mm}][%p][%C-%L] %m%n
log4j.appender.A2.File =/volume1/homes/tomcatupload/logs/system_notice.log
log4j.appender.A2.MaxFileSize=10MB 

log4j.appender.A2.DatePattern = '.'yyyyMMdd-HHmm

log4j寫到不同file
=======================================================================
  log4j.rootLogger=TRACE, stdout

  log4j.appender.stdout=org.apache.log4j.ConsoleAppender
  log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
  log4j.appender.stdout.layout.ConversionPattern=%d [%24F:%t:%L] - %m%n

  log4j.appender.debugLog=org.apache.log4j.FileAppender
  log4j.appender.debugLog.File=logs/debug.log
  log4j.appender.debugLog.layout=org.apache.log4j.PatternLayout
  log4j.appender.debugLog.layout.ConversionPattern=%d [%24F:%t:%L] - %m%n

  log4j.appender.reportsLog=org.apache.log4j.FileAppender
  log4j.appender.reportsLog.File=logs/reports.log
  log4j.appender.reportsLog.layout=org.apache.log4j.PatternLayout
  log4j.appender.reportsLog.layout.ConversionPattern=%d [%24F:%t:%L] - %m%n

  log4j.category.debugLogger=TRACE, debugLog
  log4j.additivty.debugLogger=false

  log4j.category.reportsLogger=DEBUG, reportsLog
                 可自訂 可自訂
  log4j.additivty.reportsLogger=false
 

  [The configure the loggers in the Java code thusly:]

  static final Logger debugLog = Logger.getLogger("debugLogger");
  static final Logger resultLog = Logger.getLogger("reportsLogger");
=========================================================================
[Do you want output to go to stdout? If not, change the first line of log4j.properties to:]

  log4j.rootLogger=OFF
  and get rid of the stdout lines.


參考http://stackoverflow.com/questions/9652032/how-can-i-create-2-separate-log-files-with-one-log4j-config-file [^]