If the inputfile exists, then we must create a new output file.
如果该输入文件存在，那么我们必须开辟一个新的输出文件。
2
With an input and outputfile, it's now possible to see how JAXB does at round-tripping, by comparing the files to each other (remember that the original file was shown back in Listing 1).
现在有了输入和输出文件，通过互相比较可以看看JAXB在往返中是如何工作的(原始文件如清单1所示)。
3
Obtain the selected input and outputfile locations.