发送电子邮件时出错：未找到提供者com.sun.mail.imap.IMAPProvider

Question

我正在使用javamail通过gmail帐户发送html电子邮件。它在Android模拟器上的应用程序中运行良好，但是当我在Android 9设备上安装应用程序并尝试发送电子邮件时，出现此错误：

d.b.o .：未找到提供者com.sun.mail.imap.IMAPProvider

这是我使用的课程：

import android.app.Activity;
import android.content.Context;
import android.content.SharedPreferences;
import android.os.StrictMode;
import android.text.Html;
import android.text.Spanned;
import android.util.Log;
import androidx.core.text.HtmlCompat;
import java.util.ArrayList;
import java.util.Properties;
import javax.mail.Authenticator;
import javax.mail.Message;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

public class SendHTMLEmail {

    public static boolean SendEmail(String dst, String subject, String body) {
            final String cemail;
            final String cpasswd;

            cemail= "[email protected]";
            cpasswd= "mypassword";

            StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
            StrictMode.setThreadPolicy(policy);

            Properties props = new Properties();
            props.put("mail.smtp.host", "smtp.googlemail.com");
            props.put("mail.smtp.socketFactory.port", "465");
            props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
            props.put("mail.smtp.auth", "true");
            props.put("mail.smtp.port", "465");

            try {

                Session session = Session.getDefaultInstance(props, new Authenticator() {
                    @Override
                    protected PasswordAuthentication getPasswordAuthentication() {
                        return new PasswordAuthentication(cemail, cpasswd);
                    }
                });

                if (session != null) {

                    Message message = new MimeMessage(session);
                    message.setFrom(new InternetAddress(cemail));
                    message.setSubject(subject);
                    message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(dst));
                    message.setContent(body, "text/html; charset=utf-8");

                    Transport.send(message);

                    return true;
                }
            } catch (Exception e) {
                e.printStackTrace();
                Log.e("EMAIL", e.getMessage());
            }

            return false;
    }
}

Answer 1

经过一些测试和更改，我发现了错误：

java.lang.ClassNotFoundException：com.sun.mail.imap.IMAPProvider引起原因：java.lang.ClassNotFoundException：com.sun.mail.pop3.POP3Provider

问题是ProGuard规则。可以这样解决：https://stackoverflow.com/a/57431949/1616700