jar檔可以用壓縮軟體壓縮

http://download.oracle.com/javase/1.4.2/docs/guide/extensions/spec.html

Each optional package or application consists of at least one JAR file containing an optional manifest, code and assorted resources. As described below, this primary JAR file can also include additional information in its manifest to describe dependencies on other JAR files. The jar command line tool included with the Java 2 SDK provides a convenient means of packaging optional packages, although any ZIP-compatible archiving tool should work as well.

由官方規格即知jar檔只要是ZIP相容即可,基本上我都用7-zip壓
只是jar工具程式壓的可能包含了一些相依資訊
另外放在$/JAVA_HOME/jre/lib/ext的套件也是可以壓成jar或zip檔

WebSphere設定jndi (DB2)

http://www.ibm.com/developerworks/cn/data/library/techarticles/dm-0512zhanghzh/

http://publib.boulder.ibm.com/infocenter/wasinfo/v6r0/index.jsp?topic=%2Fcom.ibm.websphere.express.doc%2Finfo%2Fexp%2Fae%2Fudat_minreq.html

使用in的欄位要有index

如果使用in的欄位沒有建index
就會TBSCAN

ex.
good.status in ('a','b','c')
gooddetail.status in ('a','b','c')


good.status沒有建index =>TBSCAN
gooddetail.status 有建index =>IXSCAN
good.status也可以調成or or的形式避免執行太久dead lock

log4j進階應用

過濾不同的Level：org.apache.log4j.varia.levelrangefilter

過濾字串(比如過濾哪種Exception才輸出)：org.apache.log4j.varia.StringMatchFilter
發送email通知：org.apache.log4j.net.SMTPAppender

ref:
http://wiki.apache.org/logging-log4j/Log4jXmlFormat

(DB2)Max number of existing agents

db2=>GET DATABASE MANAGER CONFIGURATION

Max number of existing agents是設定db2這個instance最大可用的Node Agent數目
如果AP(如:Websphere)的Connection Pool沒有到上限，資料庫卻無法連線
可能是這裡設定太小

查看LOG大檔的好幫手-KFK

http://www.kcsoftwares.com/index.php?kfk
LOG太大不好查看
可以用KFK分割，只查看某時段的LOG
方便好用，分割檔案也滿快的
也可以分割其他種檔案
但是沒用過，我都是拿來分割LOG
有中文介面，也可免安裝

另外一套工具是HJSplit，可見以下網站說明
如何使用 HJSplit 分割、合併大型檔案
https://briian.com/6810/hjsplit.html

GlassFish Full Build Instructions

http://wikis.sun.com/display/GlassFish/FullBuildInstructions