应该是eclipse出问题了，eclipse尽量备份了能够抢救的文件。（我也出现了相似情况，当时是没保存电脑就断电了，eclipse.exe源程序就出现了这个p2bu后缀。
Additional Notes on Backup for File Operation Actions
The Native Touchpoint stores a temporary backup of files that are deleted or overwritten during the installation process. If an installation succeeds the backup is simply removed. If however the installation fails, the files in backup are restored to their original location. If the restore works as expected, the backup copy is also removed. Two "disaster" cases remain:
It was not possible to restore files (probably because of faulty hardware, running out of disk, or manual tampering with files during the installation).
The system crashed during the install
The backup is placed in a directory under the directory referenced by the system property "java.io.tmpdir". The backup directory has a name with the prefix ".p2bu" which is followed by a unique key per running backup instance. Under the ".p2bu..." directory files are stored in a hierarchy that reflects their original location.
In both of the disaster cases, the backup store under java.io.tempdir will contain copies of all files that were not automatically restored. If a restore is wanted, this can be performed manually by copying the content back to their original position (which is evident from the structure under ".p2bu"). This can be made with tools like zip (simply zip everything relative to .p2bu, and then unzip it from the real file system root).
In case something goes wrong during restore of a backup, the event is logged with details of what needs to be manually restored. This is best effort support so in the case of a system crash file loss is possible.
——引用自eclipse帮助文档