> a simple refresh期：

Can you switch to the navigator view,right-click refresh the project,make sure it’s not in the LIB dir,
Then try and drag and drop the JAR into the lib dir and see if it shows up.

>流程问题(从cached blog entry开始,original one不可用)：

When you have total control of you web container/app server,deploying jar files is as easy as dropping the folder in your common lib folder.
If you don’t package your web apps as a war file then it’s even easier because you only have to drop the jars in the WEB-INF/lib folder of your webapp.
But if you don’t have total control of your web server or application server,your only choice is to package the jars you’ve used with your war file.

While developing a web project using my recently developed utility(a jar file),I encountered a NoClassDefFound error. Of course,it’s pretty obvIoUs that the jar file I’ve made and using on my web project could not be found (not visible in the CLASSPATH).
Adding the jar to the build path only eliminated the compilation problem. Dragging the jar file into the lib folder of my Eclipse workspace isn’t a very good idea.
It took me a couple of hours before I figured out the solution:

1. Right Click on your web project
2. Click Properties
3. Select J2EE Module Dependencies
4. Click the Web Libraries Tab
5. Add external jars (if the jar is outside of your project). An entry will be added under Jar/Module,make sure you click on the checkBox (checked).

And everything should be fine. I tried exporting to a war file and then checked the content and my jar files are indeed deployed with the war.

>项目配置问题

OP ufk在评论中提到：

I resolved the issue by:

• adding a “Web App Libraries” library in “java build path” and
• adding all the relevant jars into WebContent/WEB-INF/lib