实现效果开源协议Copyright(C)2016Thisprogramisfreesoftware;youcanredistributeitand/ormodifyitunderthetermsoftheGNUGeneralPublicLicenseaspublishedbytheFreeSoftwareFoundation;eitherversion2oftheLicense,or(atyouroption)anylaterversion.Thisprogramisdistributedinthehopethatitwillbeuseful,