Android Studio使用JavaMail API发邮件提示用户名/密码错误求助

你用Android Studio结合JavaMail API实现邮件发送功能，发件人和收件人是同一个Gmail邮箱，但执行代码时日志提示用户名和/或密码错误，以下是针对性的排查和解决方法：

核心原因 #

Gmail目前限制第三方应用使用普通密码登录，主要是出于账户安全考虑，常见情况是：账户开启了两步验证，或者未开启对应权限允许第三方应用访问。

解决步骤 #

1. 应用专用密码（推荐，适用于开启两步验证的账户） #

如果你的Gmail账户开启了两步验证，必须使用Google提供的应用专用密码替代普通密码：

• 登录你的Google账户，进入「安全」设置页面
• 找到「应用专用密码」选项，生成一个仅用于该Android应用的密码
• 将代码中stringPasswordSenderEmail的值替换为这个生成的密码

2. 临时开启不太安全的应用访问（仅测试用，不推荐正式环境） #

若未开启两步验证，可临时开启此选项让应用登录：

• 登录Google账户安全设置，找到「不太安全的应用访问」
• 开启该选项（注意：此操作会降低账户安全性，正式发布的应用不要使用）

3. 代码优化建议 #

你的代码配置基本正确，可补充以下配置确保SSL连接稳定：

// 在properties配置中添加
properties.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");

4. 其他检查点 #

• 确认发件人邮箱地址拼写完全正确，Gmail不区分大小写，但代码中尽量保持一致
• 确认设备网络正常，能正常访问Gmail服务器

以下是你提供的代码：

MainActivity.java

import android.os.Bundle;
import android.view.View;

import java.util.Properties;

import javax.mail.Authenticator;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void buttonSendEmail(View view){

        try {
            String stringSenderEmail = "SenderEmail963@gmail.com";
            String stringReceiverEmail = "receiveremail963@gmail.com";
            String stringPasswordSenderEmail = "Test*123";

            String stringHost = "smtp.gmail.com";

            Properties properties = System.getProperties();

            properties.put("mail.smtp.host", stringHost);
            properties.put("mail.smtp.port", "465");
            properties.put("mail.smtp.ssl.enable", "true");
            properties.put("mail.smtp.auth", "true");

            javax.mail.Session session = Session.getInstance(properties, new Authenticator() {
                @Override
                protected PasswordAuthentication getPasswordAuthentication() {
                    return new PasswordAuthentication(stringSenderEmail, stringPasswordSenderEmail);
                }
            });

            MimeMessage mimeMessage = new MimeMessage(session);
            mimeMessage.addRecipient(Message.RecipientType.TO, new InternetAddress(stringReceiverEmail));

            mimeMessage.setSubject("Subject: Android App email");
            mimeMessage.setText("Hello Programmer, \n\nProgrammer World has sent you this 2nd email. \n\n Cheers!\nProgrammer World");

            Thread thread = new Thread(new Runnable() {
                @Override
                public void run() {
                    try {
                        Transport.send(mimeMessage);
                    } catch (MessagingException e) {
                        e.printStackTrace();
                    }
                }
            });
            thread.start();

        } catch (AddressException e) {
            e.printStackTrace();
        } catch (MessagingException e) {
            e.printStackTrace();
        }
    }
}

build.gradle (Module level)

plugins {
    id 'com.android.application'
}

android {
    compileSdk 31

    defaultConfig {
        applicationId "com.programmerworld.sendemailapp"
        minSdk 31
        targetSdk 31
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

    packagingOptions{
        exclude 'META-INF/NOTICE.md'
        exclude 'META-INF/LICENSE.md'
    }

}

dependencies {

    implementation 'androidx.appcompat:appcompat:1.4.1'
    implementation 'com.google.android.material:material:1.5.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.1.3'
    testImplementation 'junit:junit:4.13.2'
    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'

    implementation 'com.sun.mail:android-mail:1.6.6'
    implementation 'com.sun.mail:android-activation:1.6.7'

}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.programmerworld.sendemailapp">

    <uses-permission android:name="android.permission.INTERNET"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.SendEmailApp">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="105dp"
        android:layout_marginTop="103dp"
        android:onClick="buttonSendEmail"
        android:text="Send Email"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

内容的提问来源于stack exchange，提问作者wuad