获取openid失败？

后台请求https:api.weixin.qq.com/sns/jscode2session?报错，报错信息：javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target，请问怎么解决