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2005年03月18日
Ajax渐热
最近在国外的blog看到Ajax出现的次数越来越多了,应用的例子也越来越多了,google的新东东,如google suggest、google map、gmail等都用了Ajax,看来会成为一个趋势了。
Ajax是什么?
Ajax是Jesse James Garrett在Ajax: A New Approach to Web Applications中先提出来的。引用: The name is shorthand for Asynchronous JavaScript + XML, and it represents a fundamental shift in what’s possible on the Web.
Ajax isn’t a technology. It’s really several technologies, each flourishing in its own right, coming together in powerful new ways. Ajax incorporates:
standards-based presentation using XHTML and CSS;
dynamic display and interaction using the Document Object Model;
data interchange and manipulation using XML and XSLT;
asynchronous data retrieval using XMLHttpRequest;
and JavaScript binding everything together
Ajax的代码片段:http://www.fiftyfoureleven.com/resources/programming/xmlhttprequest/examples
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2005年03月16日
MyEclipse与Eclipse的版本对应关系
MyEclipse是Eclipse中相当特殊的插件,安装它的话一定要看它是对应哪个版本的eclipse,如果版本不兼容的话会有相当多的问题的,如语法高亮丢失、打开XML文件出错等等。
目前最新的MyEclipse的版本是3.8.4,是for eclipse 3.1M4的。
又,eclipse 3.1M5a的性能不如3.1M4(网上有测试,个人感觉也如此),加上与MyEclipse的兼容性问题,不建议安装3.1M5a。
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2005年03月07日
如何选择Cache组件?
Java世界开源的好东东太多,享受高质量的选择的同时也常常面临抉择的痛苦。这不,要用一个Cache组件都是一个dilemma:Ehcache or OSCache?
Ehcache出自Hibernate,后来才自立门户,不过,由于与Hibernate的血缘关系,自然是Hibernate的推荐cache了;而且acegi也用了Ehcache。然而OSCache是OpenSymphony(http://www.opensymphony.com)出品的,也自不凡(OS出品,必属精品:-)),而且OSCache还有一个WEB 组件 可以根据URL等缓存动态页面。
如何选择?嗯,鱼与熊掌兼得最好了,Ehcache与OSCache并无任何的兼容性问题,就让它们各展所长好了:hibernate/acegi使用EhCache,而web页面缓存采用OSCache。 -
2005年02月18日
Tomcat5.5.X与Tomcat5.0.X配置数据库连接池的不同之处
Tomcat5.0.X配置数据库连接池,是分别配置Resource和ResourceParams,如代码: <Resource name="jdbc/ExampleDB" auth="Container" type="javax.sql.DataSource"/>
<ResourceParams name="jdbc/ExampleDB">
<parameter>
<name>factory</name>
<value>org.apache.commons.dbcp.BasicDataSourceFactory</value>
</parameter>
<!-- Maximum number of dB connections in pool. Make sure you
configure your mysqld max_connections large enough to handle
all of your db connections. Set to 0 for no limit.
-->
<parameter>
<name>maxActive</name>
<value>100</value>
</parameter>
<!-- Maximum number of idle dB connections to retain in pool.
Set to 0 for no limit.
-->
<parameter>
<name>maxIdle</name>
<value>30</value>
</parameter>
<!-- Maximum time to wait for a dB connection to become available
in ms, in this example 10 seconds. An Exception is thrown if
this timeout is exceeded. Set to -1 to wait indefinitely.
-->
<parameter>
<name>maxWait</name>
<value>10000</value>
</parameter>
<!-- MySQL dB username and password for dB connections -->
<parameter>
<name>username</name>
<value>root</value>
</parameter>
<parameter>
<name>password</name>
<value></value>
</parameter>
<!-- Class name for mm.mysql JDBC driver -->
<parameter>
<name>driverClassName</name>
<value>com.mysql.jdbc.Driver</value>
</parameter>
<!-- The JDBC connection url for connecting to your MySQL dB.
The autoReconnect=true argument to the url makes sure that the
mm.mysql JDBC Driver will automatically reconnect if mysqld closed the
connection. mysqld by default closes idle connections after 8 hours.
-->
<parameter>
<name>url</name>
<value>jdbc:mysql://192.168.0.88:3306/quickoa</value>
</parameter>
</ResourceParams>
而在Tomcat5.5.X中,这两者合二为一了,直接配置Resource就可以了,如代码: <Resource name="jdbc/ExampleDB" auth="Container"
type="javax.sql.DataSource" driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost/quickoa" username="root"
password="" maxActive="100" maxIdle="30" maxWait="10000" />
又,值得注意的是在Tomcat5.5.X中,dbcp组件需要自己额外下载的,不像在Tomcat5.0.X中已经附带了。 -
2005年01月28日
Hibernate - XDoclet Tutorial
http://www.downside.ch/hibernate/
The tutorial covers the generation of Hibernate mapping files with XDoclet. If you are new to the Hibernate/XDoclet combo and want to have a glimpse into the world of ORM tools or you are just interested in some mapping examples then this is for you.







