1.右键项目-》属性-》java bulid path-》jre System Library-》access rules-》resolution选择accessible，下面填上** 点击确定即可。
2.在MyEclipse中编写Java代码时，用到了BASE64Decoder，import sun.misc.BASE64Decoder；可是Eclipse提示：
Access restriction: The type BASE64Decoder is not accessible due to restriction on required library C:\Program
files\java\jre6\lib\rt.jar
Access restriction : The constructor BASE64Decoder() is not accessible due to restriction on required library C:\Program files\java\jre6\lib\rt.jar
解决方案1（推荐）：
只需要在project build path中先移除JRE System Library，再添加库JRE System Library，重新编译后就一切正常了。
解决方案2：
Windows -> Preferences -> Java -> Compiler -> Errors/Warnings ->
Deprecated and trstricted API -> Forbidden reference (access rules): -> change to warning
原文来自：http://blog.csdn.net/jbxiaozi/article/details/7351768
