导入以前的web项目后会出现以下三个错误：
1. Archive for required library: ‘WebContent/WEB-INF/lib/readme.txt’ in project ‘xxxxxxxxx’ cannot be read or is not a valid ZIP file
2. The project cannot be built until build path errors are resolved
3. Target runtime Apache Tomcat v6.0 is not defined.
这三个问题都很好解决，方法如下：
1. 用记事本打开项目根目录的.classpath文件，找到“<classpathentry kind=”lib” path=”WebContent/WEB-INF/lib/readme.txt”/>”这一行，删掉
2. 第一个问题解决后，此问题也会消失
3. 打开项目根目录下.settings文件夹中的org.eclipse.wst.common.project.facet.core.xml文件，将“<runtime name=”Apache Tomcat v6.0″/>”这一句改成现在所需要的tomcat版本，或者删除中间几行，只留下下面三行就行 “<?xml version=”1.0″ encoding=”UTF-8″?> <faceted-project> </faceted-project>”