Erreur dans JavaMail : PKIX chemin d'accès du bâtiment a échoué impossible de trouver le chemin de certification valide à la demande de la cible

Je suis en train de construire un client de messagerie app android, et maintenant je veux configurer le javaMail partie.

que j'essaie d'établir la connexion avec le serveur imap mais quelque chose de mal avec mon code..
voici mon code:

package mailpackage;
import java.util.Properties;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.NoSuchProviderException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Store;
public class Connection implements Runnable
{
boolean done;
public Connection()
{
this.done=false;
}
@Override
public void run()
{
System.out.println("Hello from Connection Thread!");
while(!done)
{
String host = "myhost";//change accordingly
String mailStoreType = "imap";
String username = "myusername";//change accordingly
String password = "mypasswd";//change accordingly
check(host, mailStoreType, username, password);
}
}
public static void receiveEmail(String host, String storeType,  String username, String password)
{
try
{
Properties properties = new Properties();  
properties.put("mail.imap.com", host);  
properties.put("mail.imap.starttls.enable","true");
properties.put("mail.imap.auth", "true");  //If you need to authenticate
//Use the following if you need SSL
properties.put("mail.imap.socketFactory.port", 993);
properties.put("mail.imap.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
properties.put("mail.imap.socketFactory.fallback", "false");
Session emailSession = Session.getDefaultInstance(properties);  
emailSession.setDebug(true);
//2) create the IMAP store object and connect with the Imap server  
IMAPStore emailStore = (IMAPStore) emailSession.getStore(storeType);
emailStore.connect(host, username, password);  
//3) create the folder object and open it  
Folder emailFolder = emailStore.getFolder("INBOX");  
emailFolder.open(Folder.READ_ONLY);  
//4) retrieve the messages from the folder in an array and print it  
Message[] messages = emailFolder.getMessages();  
for (int i = 0; i <messages.length; i++) 
{
Message message = messages[i];  
MimeMessage m = new MimeMessage(emailSession);
m.setContent(((MimeMessage)messages[i]).getContent() , "text/plain; charset=UTF-8");
System.out.println("---------------------------------");  
System.out.println("Email Number " + (i + 1));  
System.out.println("Subject: " + message.getSubject());  
System.out.println("From: " + message.getFrom()[0]);  
System.out.println("Text: " + message.getContent().toString());  
m.writeTo(System.out);
}  
//5) close the store and folder objects  
emailFolder.close(false);  
emailStore.close();  
} 
catch (NoSuchProviderException e) {e.printStackTrace();}   
catch (MessagingException e) {e.printStackTrace();}  
catch (IOException e) {e.printStackTrace();}
}
public void stopThread()
{
this.done=true;
}
}

J'appelle le fil d'une autre classe, comme ce

connec=new Connection();
(new Thread(connec)).start();

J'obtiens les erreurs Suivantes:

javax.mail.MessagingException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target;
nested exception is:
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 com.sun.mail.imap.IMAPStore.protocolConnect(IMAPStore.java:571)
at javax.mail.Service.connect(Service.java:288)
at javax.mail.Service.connect(Service.java:169)
at mailpackage.Connection.check(Connection.java:63)
at mailpackage.Connection.run(Connection.java:33)
at java.lang.Thread.run(Thread.java:744)
Caused by: 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:1884)
at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:276)
at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:270)
at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1341)
at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:153)
at sun.security.ssl.Handshaker.processLoop(Handshaker.java:868)
at sun.security.ssl.Handshaker.process_record(Handshaker.java:804)
at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1016)
at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1312)
at sun.security.ssl.SSLSocketImpl.readDataRecord(SSLSocketImpl.java:882)
at sun.security.ssl.AppInputStream.read(AppInputStream.java:102)
at com.sun.mail.util.TraceInputStream.read(TraceInputStream.java:110)
at java.io.BufferedInputStream.fill(BufferedInputStream.java:235)
at java.io.BufferedInputStream.read(BufferedInputStream.java:254)
at com.sun.mail.iap.ResponseInputStream.readResponse(ResponseInputStream.java:98)
at com.sun.mail.iap.Response.<init>(Response.java:96)
at com.sun.mail.imap.protocol.IMAPResponse.<init>(IMAPResponse.java:61)
at com.sun.mail.imap.protocol.IMAPResponse.readResponse(IMAPResponse.java:135)
at com.sun.mail.imap.protocol.IMAPProtocol.readResponse(IMAPProtocol.java:261)
at com.sun.mail.iap.Protocol.<init>(Protocol.java:114)
at com.sun.mail.imap.protocol.IMAPProtocol.<init>(IMAPProtocol.java:104)
at com.sun.mail.imap.IMAPStore.protocolConnect(IMAPStore.java:538)
... 5 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 sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:385)
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:326)
at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:231)
at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:126)
at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1323)
... 23 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:196)
at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:268)
at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:380)
... 29 more

j'ai lu quelque chose à propos de PKIX chemin erreur qui dit que pour ajouter le cert de java magasin de confiance cert, mais je ne sais pas si c'est la solution pour ce faire, et si elle est, je ne sais pas comment le faire.

//je n'ai pas accès au serveur de messagerie

Des suggestions? merci!