Java 使用p12证书从HTTPS访问JSON时发生异常

使用Java，我必须从带有p12证书的URL读取JSON字符串。我已使用成功地将证书导入jre1.8.0_51\lib\security\cacerts

keytool -importkeystore -deststorepass changeit -destkeystore cacerts -srckeystore ..\certificate\cert1.p12 -srcstoretype pkcs12 -srcstorepass mypass -alias cert1

我还可以在Chrome中看到JSON字符串。但是，当我尝试从Java阅读时，我得到：

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

我正在使用以下代码：

URL url = new URL("https://myurl");
KeyStore ks = KeyStore.getInstance("PKCS12");
FileInputStream fis = new FileInputStream("certificate/cert1.p12");
ks.load(fis, "mypass".toCharArray());
TrustManagerFactory tmf = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
tmf.init(ks);

KeyManagerFactory kmf = KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm());
kmf.init(ks, "mypass".toCharArray());

SSLContext sslCtx = SSLContext.getInstance("TLS");
sslCtx.init(kmf.getKeyManagers(), tmf.getTrustManagers(), null);
SSLSocketFactory sslSF = sslCtx.getSocketFactory();

URLConnection conn = url.openConnection();
if(conn instanceof HttpsURLConnection) {
            ((HttpsURLConnection) conn).setSSLSocketFactory(sslSF);
}
conn.connect();

但是，此代码会产生obove异常。我在Windows10上。我错过了什么？谢谢