The type HttpExchange is not accessible due to restriction on required library 错误

参考：http://stackoverflow.com/questions/860187/access-restriction-on-class-due-to-restriction-on-required-library-rt-jar

问题描述：

import com.sun.net.httpserver.HttpExchange;

报错

Access restriction: The type HttpExchange is not accessible due torestriction on required library C:\Program Files\Java\jre7\lib\rt.jar

解决：

将 JRE System Library 从 Libraries 中删除，然后重新添加 JRE System Library

原因：

工程中存在多个jar中的多个class冲突，其中只有一个class是正确的class。

删除 JRE System Library 后重新添加，会让正确的class成为首选class，从而被正确找到。

（This works because you have multiple classes in different jar files. Removing and re-adding the jre lib will make the right classes be first. If you want a fundamental solution make sure you exclude the jar files with the same classes.）