Usage of NetBean 6.x Editor

Hot keys:

1. Ctrl + space : Code completion.
   
2. Alt + Insert : Generate "getter and setter; constructor; delegate; add property; etc"
   
3. Alt + Enter : ???
   
4. Ctrl + R : factoring name.
   
5. Shift + Esc : enlarge current window.
   

Tutorial on using NetBean IDE

Persist LOB using JPA in J2EE/J2SE

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JPA (Sun persistence standard)==> Persistence Provider (Toplink) ==> JDBC (version 11.)

1) JPA provides a simple solution for persisting LOB in Database. Developer only need to annotate the Entity variable that is a LOB. Looks like that, at least from the document, that I have read.
2) However, persistence manager seems cannot persist a string bigger than 4000 byte. Why?
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The reason is that the JDBC driver, I am using, ojdbc14.jar, which is only compatible for jdk1.4 not for jdk1.5. It doesn't support write BLOB into database just like writing in a String. So I download the latest version JDBC driver, ojdbc5.jar, and problem solved at once.
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JDBC driver: ojdbc14.

• Specification-Title: "Oracle JDBC driver classes for use with JDK1.4"
• Specification-Version: "Oracle JDBC Driver version - 9.0.2.0.0"

JDBC driver 10.2 above, it can treat Clob as if they were strings, with code like:

ps = conn.createPreparedStatement( "update tab set lob =?");
ps.setString(1,"Bob")

The actual way this is done internally depends on the size of String set on the bind-parameter.

Better performance can be squeezed out of this for String between 4000 bytes and 32Kb, using a bit of PL/SQL:

ps = conn.prepareStatement("begin \n
update tab set lob= ? where id = ?;\n
End;")
Ps.setString(1, StringUpTo32K);

Log4j notes

log4j.rootLogger=debug, stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d [%t] %-5p %c{1} - %m%n

Log4j提供的appender有以下几种：

1. org.apache.log4j.ConsoleAppender（控制台）
2. org.apache.log4j.FileAppender（文件）
3. org.apache.log4j.DailyRollingFileAppender（每天产生一个日志文件）
4. org.apache.log4j.RollingFileAppender（文件大小到达指定尺寸的时候产生新文件）
5. org.apache.log4j.WriterAppender（将日志信息以流格式发送到任意指定的地方）

Log4j提供的layout有以下几种：

1. org.apache.log4j.HTMLLayout（以HTML表格形式布局），
2. org.apache.log4j.PatternLayout（可以灵活地指定布局模式），
3. org.apache.log4j.SimpleLayout（包含日志信息的级别和信息字符串），
4. org.apache.log4j.TTCCLayout（包含日志产生的时间、线程、类别等等信息）

Log4j 自定义格式

1. %p 输出优先级，即DEBUG，INFO，WARN，ERROR，FATAL
2. %r 输出自应用启动到输出该log信息耗费的毫秒数
3. %c 输出所属的类目，通常就是所在类的全名
4. %t 输出产生该日志事件的线程名
5. %n 输出一个回车换行符，Windows平台为“\r\n”，Unix平台为“\n”
6. %d 输出日志时间点的日期或时间，默认格式为ISO8601，也可以在其后指定格式，比如：%d{yyy MMM dd HH:mm:ss,SSS}，输出类似： 2002年10月18日 22：10：28，921
7. %l 输出日志事件的发生位置，包括类目名、发生的线程，以及在代码中的行数。举例：Testlog4.main(TestLog4.java:10)