我试图在Android中构建一个电子邮件客户端应用程序，现在我想配置javaMail部分。
我试图建立与imap服务器的连接，但我的代码有问题..这是我的代码：

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;
    }
}

字符串
我从另一个类调用线程，就像这样

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

型
我得到以下错误：

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

型
我读了一些关于PKIX路径错误的东西，说要将证书作为可信证书添加到Java存储中，但我不知道这是否是解决方案，如果是，我不知道如何做到这一点。
//我无法访问邮件服务器
有什么建议吗？谢谢！