找到出错的jar包文件位置，删掉_maven.repositories文件（或用文本编辑器打开，将“>main=”改为“>=”，即删除main，当然main也可能是其他值），然后update project。
_maven.repositories简介：
_maven.repositories hold the information about the origin of the artefacts. Maven tries to update your jar from the old location (as saved in _maven.repositories) and fails. The presumtion here is that the same aftifact on a different remote repository might be different.
eclipse导入maven工程missing artifact（实际是存在的）错误解决
原文：http://www.cnblogs.com/zxy500/p/5836044.html