已解决 - 我通过将我的cacerts文件从我的Windows机器复制到pi来解决它。
我正在编写一个应用程序，使用长轮询从Web服务器获取json字符串，应用程序在我正在开发的Windows机器上正常运行。然后我将源代码移动到了覆盆子pi并编译它，现在它抛出了这个异常：
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
at sun.security.ssl.Alerts.getSSLException(Alerts.java:192)
at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1917)
at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:301)
at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:295)
at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1369)
at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:156)
at sun.security.ssl.Handshaker.processLoop(Handshaker.java:925)
at sun.security.ssl.Handshaker.process_record(Handshaker.java:860)
at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1043)
at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1343)
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1371)
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1355)
at sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:563)
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:185)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1511)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1439)
at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:254)
at VideoBoard.main(VideoBoard.java:29)
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:387)
at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:292)
at sun.security.validator.Validator.validate(Validator.java:260)
at sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:324)
at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:229)
at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:124)
at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1351)
... 13 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
at sun.security.provider.certpath.SunCertPathBuilder.build(SunCertPathBuilder.java:145)
at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:131)
at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:280)
at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:382)
... 19 more
我的网站由GoDaddy托管，他们也提供SSL证书。通过浏览器或java从我的桌面访问站点时没有任何问题，并且所有迹象表明SSL证书有效且受我的机器信任。