Java API connectiong failed: PKIX path-CodePudding

I have been seeking for some solutions about javax.net.ssl.SSLHandshakeException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target exception, but the solutions that are provided in the posts I read did not solve the issue, that is why I am asking here.

Basically, in my code, I am using Unirest for connection, as the code below:

public void httpConnectionHourlyPred() {
   try {
      Map<String, String> asHeaders = new HashMap<String, String>();
      asHeaders.put("cache-control", "no-cache");
      asHeaders.put("api_key", getsKey());
      HttpResponse response = Unirest.get(sURLHourlyPred).headers(asHeaders).asString();
      System.out.println(response);
}

The API to which I am connecting the AEMET Open Data service (

The same script for python also works and I got the result. However, due to the use of a hardware only compatible with Java, I have to program in Java. Thus, when I run the script, I obtain the exception below. I am using the OpenJDK virtual machine (in particular, openjdk-8u312-b07). How could I fix it?

Many thanks in advance

com.mashape.unirest.http.exceptions.UnirestException: javax.net.ssl.SSLHandshakeException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at com.mashape.unirest.http.HttpClientHelper.request(HttpClientHelper.java:143)
    at com.mashape.unirest.request.BaseRequest.asString(BaseRequest.java:56)
    at es.cartif.aemet.AEMETConnector.httpConnectionHourlyPred(AEMETConnector.java:55)
    at es.cartif.main.AEMETMain.main(AEMETMain.java:10)
Caused by: javax.net.ssl.SSLHandshakeException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at java.base/sun.security.ssl.Alert.createSSLException(Alert.java:131)
    at java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:369)
    at java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:312)
    at java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:307)
    at java.base/sun.security.ssl.CertificateMessage$T12CertificateConsumer.checkServerCerts(CertificateMessage.java:654)
    at java.base/sun.security.ssl.CertificateMessage$T12CertificateConsumer.onCertificate(CertificateMessage.java:473)
    at java.base/sun.security.ssl.CertificateMessage$T12CertificateConsumer.consume(CertificateMessage.java:369)
    at java.base/sun.security.ssl.SSLHandshake.consume(SSLHandshake.java:396)
    at java.base/sun.security.ssl.HandshakeContext.dispatch(HandshakeContext.java:480)
    at java.base/sun.security.ssl.HandshakeContext.dispatch(HandshakeContext.java:458)
    at java.base/sun.security.ssl.TransportContext.dispatch(TransportContext.java:199)
    at java.base/sun.security.ssl.SSLTransport.decode(SSLTransport.java:171)
    at java.base/sun.security.ssl.SSLSocketImpl.decode(SSLSocketImpl.java:1497)
    at java.base/sun.security.ssl.SSLSocketImpl.readHandshakeRecord(SSLSocketImpl.java:1403)
    at java.base/sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:441)
    at java.base/sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:412)
    at org.apache.http.conn.ssl.SSLConnectionSocketFactory.createLayeredSocket(SSLConnectionSocketFactory.java:290)
    at org.apache.http.conn.ssl.SSLConnectionSocketFactory.connectSocket(SSLConnectionSocketFactory.java:259)
    at org.apache.http.impl.conn.HttpClientConnectionOperator.connect(HttpClientConnectionOperator.java:125)
    at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.connect(PoolingHttpClientConnectionManager.java:319)
    at org.apache.http.impl.execchain.MainClientExec.establishRoute(MainClientExec.java:363)
    at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:219)
    at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:195)
    at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:86)
    at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:108)
    at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:184)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:106)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:57)
    at com.mashape.unirest.http.HttpClientHelper.request(HttpClientHelper.java:138)
    ... 3 more
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 java.base/sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:439)
    at java.base/sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:306)
    at java.base/sun.security.validator.Validator.validate(Validator.java:264)
    at java.base/sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:231)
    at java.base/sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:132)
    at java.base/sun.security.ssl.CertificateMessage$T12CertificateConsumer.checkServerCerts(CertificateMessage.java:638)
    ... 28 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at java.base/sun.security.provider.certpath.SunCertPathBuilder.build(SunCertPathBuilder.java:141)
    at java.base/sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:126)
    at java.base/java.security.cert.CertPathBuilder.build(CertPathBuilder.java:297)
    at java.base/sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:434)
    ... 33 more
Error making the data request javax.net.ssl.SSLHandshakeException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

CodePudding user response：

It looks like you didn't configured the ssl configuration of Unirest. The specific exceptions could mean that the server is not trusted by the client. What you could do is extract the certificate from:

I would advice to put the certificate into either a p12 or jks truststore file and create a sslcontext out of it.

Here is a code snippet for creating a sslcontext from a truststore:

InputStream trustStoreStream = ...; // your InputStream from the trust store file

KeyStore trustStore = KeyStore.getInstance(KeyStore.getDefaultType());
trustStore.load(trustStoreStream, "password".toCharArray());

TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
trustManagerFactory.init(trustStore);

SSLContext sslContext = SSLContext.getInstance("TLS");
sslContext.init(null, trustManagerFactory.getTrustManagers(), null);

And configure your primary instance of Unirest like the snippet below:

Unirest.primaryInstance()
    .config()
    .sslContext(sslContext)