最近时不时老遇到这个问题，怎么解决：？
eclipse项目编译版本是1.6,但是引用的jar包的编译版本是1.7
，报错信息如下：
Description Resource Path Location Type Incompatible .class files version in required binaries. Project '28[nanjing]' is targeting a 1.6 runtime, but is compiled against '28[nanjing]/lib/capitalapi.jar' which requires a 1.7 runtime 28[nanjing] Build path Build Path Problem
有时候也会遇到这个问题：
Description Resource Path Location Type The project cannot be built until build path errors are resolved 28[nanjing] Unknown Java Problem
