在巨大的目录中转换XML时的java.lang.OutOfMemoryError

I want to transform XML files using XSLT2, in a huge directory with a lot of levels. There are more than 1 million files, each file is 4 to 10 kB. After a while I always receive java.lang.OutOfMemoryError: Java heap space.I want to transform XML files using XSLT2, in a