eclipse的工程類型切換

onverting a Java project to a Dynamic Web project in Eclipse (基於WTP，通過Project Facets)

What's WTP?
http://www.eclipse.org/projects/project_summary.php?projectid=webtools

引用The Eclipse Web Tools Platform (WTP) project extends the Eclipse platform with tools for developing Web and Java EE applications. It includes source and graphical editors for a variety of languages, wizards and built-in applications to simplify development, and tools and APIs to support deploying, running, and testing apps.

Converting a Java project to a Dynamic Web project in Eclipse:
http://greatwebguy.com/programming/eclipse/converting-a-java-project-to-a-dynamic-web-project-in-eclipse/

Eclipse – Project Facets:
http://www.beilers.com/2009/05/eclipse-project-facets/

將MyEclipse項目匯入到Eclipse中：
http://todaydiy.blog.163.com/blog/static/104189687201021035312604/

引用1.請首先確保你的eclipse是javaee版本的，或者已經安裝看wtp外掛程式
2.然後修改eclipse工程下的.project檔案： Xml代碼  

1. <!--在 <natures></natures>中加入-->  
2.     <nature>org.eclipse.wst.common.project.facet.core.nature</nature>  
3.     <nature>org.eclipse.wst.common.modulecore.ModuleCoreNature</nature>  
4.     <nature>org.eclipse.jem.workbench.JavaEMFNature</nature>  
5.   
6. <!--在 <buildSpec></buildSpec>中加入-->  
7.      <buildCommand>  
8.         <name>org.eclipse.wst.common.project.facet.core.builder</name>  
9.         <arguments>  
10.         </arguments>  
11.     </buildCommand>  
12.     <buildCommand>  
13.         <name>org.eclipse.wst.validation.validationbuilder</name>  
14.         <arguments>  
15.         </arguments>  
16.     </buildCommand>  

3.重新整理項目，項目->右擊->Properties->Project Facets->Modify Project，選擇Java和Dynamic Web Module
          配置Context Root 和Content Directory 以及源碼路徑。

A Error：

引用Java compiler level does not match the version of the installed Java project facet

解決：
http://www.eclipsezone.com/eclipse/forums/t80428.html

引用 A wtp project is composed of multiple units of functionality (known as facets).
Take a look at Project Properties -> Project Facets panel. The java facet version needs to always match the java compiler compliance level.
The best way to change java level is to use the Project Facets properties panel as that will update both places at the same time. 
Alternatively, when you get the error that you are referring to, there are quick fixes available to resolve it.