web.xml 文件报错：Referenced file contains errors、cvc-id.3:A field of identity constraint

引言：导入maven工程，web.xml 报了三个错误！错误截图如下：    1.Referenced file contains errors (file:/D:/MyEclipse+/MyEclipse/configuration/org.eclipse.osgi/980/0/.cp/dtdsAndSchemas/  web-app_3_0.xsd). For more information

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