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