R tm包用于预测分析。如何对新文档进行分类？

This is a general question about the procedures concerning text mining. Suppose one has a Corpus of documents classified as Spam/No_Spam. As standard procedure one pre-process the data, removing punctuation, stops words etc. After converting it into a DocumentTermMatrix one can build some models to predict spam/No_Spam. Here is my problem. Now I want to use the model built for new documents arrive. In order to check a single document I would have to build a DocumentTerm*This is a general question about the procedures