简介

JavaEE在开发的时候，如果是系统内部常量，一般提倡用枚举常量类，写在单独的类中，但是经常要修改的变量,比如数据源配置，如果存在数据库中，有种浪费。但是存在TXT中扩展性不好，就笔者观察，一般的程序员都喜欢把经常修改的常量存在xml文件或者properties文件。



存在xml文件最大的好处是扩展性很好，一般用sax或者dom这两个方向的框架，比如DOM4J,JDOM等。Sun推出的JAXM(Java API for XML Messaging)也是用的DOM4J。由于SAX的处理方式类似流媒体，是逐行的，不需要全部加载。而DOM是全部加载在内存，生成树。因而SAX的读取比DOM性能好，但是修改的话DOM略胜一筹。properties文件的扩展性不如xml，但是有很多xml没法实现的优势，比如加密之类的~



Helloworld

笔者根据自己开发中感受，写了一个工具包，用来体现读取xml或者properties的流程，大家在使用的时候记得修改文件路径。一共包含五个文件.本demo主要是用来模拟读取数据库的账户和密码的，读者可以在此基础上扩展。-Brief introduction

JavaEE development at the time, if the system constants are generally used to promote constant enumeration type, write in a separate category, but often want to modify the variables, such as the data source configuration, if the database exist, in one waste. But the existence of bad TXT extension on my observation, the programmers in general are often modified to enjoy the constant existence xml documents or document properties.



Xml files exist to expand the biggest benefits of a good sax or dom in general with the direction of these two frameworks, such as DOM4J, JDOM, etc.. Sun introduced JAXM (Java API for XML Messaging) is also used DOM4J. SAX approach because a similar streaming media, are progressive and do not need the full load. And DOM are all loaded in memory, spanning tree. SAX and thus the better read performance than the DOM, but DOM is better if modified. properties of paper as an extension of xml, but can not realize there is a lot of the advanta