xalan.jar版本引发的问题

java.lang.NoClassDefFoundError: org/apache/xml/serializer/TreeWalker
at org.apache.xalan.processor.TransformerFactoryImpl.newTransformer(TransformerFactoryImpl.java:821)
at com.fredck.FCKeditor.connector.ConnectorServlet.doGet(ConnectorServlet.java:151)
找不到TreeWalker这个类。 原本这个类是包含在xalan.jar中的，但是xalan-j2.7.0版的发布包中，将serializer包中的类单独打包成serializer.jar，不再包含在xalan.jar中，所以才会即使添加了xalan.jar也无法找到该类，添加后即可解决问题。
网上的相关资料：
> You need to include serializer.jar file also. This file includes the
> serializer. In the Xalan Java 2.7 release, serializer code is included in
> this jar file. The release 2.6 has serializer code included in the
> xalan.jar file.