使用 Gmail api 通过 Android 应用发送邮件

Question

我知道有很多教程、问题等，过去几周我一直在努力，但无法弄清楚。

我正在开发一个 Android 应用程序，我想使用我的 gmail 帐户向某个电子邮件地址发送电子邮件。

我已阅读所有 Google Developers 文档并尝试了所有示例，但仍然无法实现。

1.首先 - 我必须拥有 G Suite 帐户吗？它没有说我这样做，但Gmail Api overview 在 G Suite 部分下？？

如果我不需要 G Suite -

2.这是right guide通过应用发送邮件吗？

如果是这样

3. 我怎样才能获得Gmail service？我在console.developers.google 中打开了一个项目并得到了OAuth 2.0 Client IDs json 文件，但是我找不到如何在Android 中使用它来获取凭据的解释。

拜托，我知道这些是个大问题，但我迫切需要帮助。请给我任何答案或正确的链接（我还没有访问过......）。我也将感谢通过聊天/邮件等提供的帮助。

谢谢

编辑 8/10 我现在的代码：

主要活动 调用 AsyncMail

AsyncMail.java

package com.send.mymailapplication;

import android.content.Context;
import android.content.res.AssetManager;
import android.os.AsyncTask;

import com.google.api.client.extensions.android.http.AndroidHttp;
import com.google.api.client.http.HttpRequestInitializer;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.client.util.Base64;
import com.google.api.services.gmail.Gmail;
import com.google.api.services.gmail.GmailScopes;
import com.google.api.services.gmail.model.Message;
import com.google.auth.http.HttpCredentialsAdapter;
import com.google.auth.oauth2.AccessToken;
import com.google.auth.oauth2.GoogleCredentials;
import com.google.common.collect.Lists;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Collections;
import java.util.Properties;

import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;



public class AsyncMail extends AsyncTask<String, Void, Void> {

    Context context;

    static HttpTransport HTTP_TRANSPORT = AndroidHttp.newCompatibleTransport();
    static JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();

    public AsyncMail (Context c) {
        context = c;
    }


    @Override
    protected Void doInBackground (String... strings) {


        try {

            AssetManager assetManager = context.getAssets();
            InputStream jsonStream = assetManager.open("mail.json");

            // those 2 tryings also works but gave me the same error
            /*ServiceAccountCredentials sourceCredentials = ServiceAccountCredentials.fromStream(jsonStream);
            sourceCredentials = (ServiceAccountCredentials) sourceCredentials.createScoped(Arrays.asList("https://mail.google.com/", "https://www.googleapis.com/auth/iam"));

            GoogleCredential credential = GoogleCredential.fromStream(jsonStream).createScoped(Lists.newArrayList("https://www.googleapis.com/auth/cloud-platform", GmailScopes.MAIL_GOOGLE_COM));
            Gmail gmail = new Gmail.Builder(HTTP_TRANSPORT, JSON_FACTORY, credential).build();*/


            GoogleCredentials credential = GoogleCredentials.fromStream(jsonStream)
                           .createScoped(Lists.newArrayList("https://www.googleapis.com/auth/cloud-platform", "https://www.googleapis.com/auth/dialogflow", GmailScopes.MAIL_GOOGLE_COM));
            credential.refreshIfExpired();
            AccessToken accessToken = credential.getAccessToken ();
            String AuthToken = accessToken.getTokenValue ();


            HttpRequestInitializer requestInitializer = new HttpCredentialsAdapter (credential);


            Gmail gmail = new Gmail.Builder(HTTP_TRANSPORT, JSON_FACTORY, requestInitializer).build();

            MimeMessage mimeMessage = createEmail ("avitalh@gmail.com", "sendmail@mail-291708.iam.gserviceaccount.com", "subbb", "bodyyyy");

            Message message = createMessageWithEmail(mimeMessage);

            gmail.users().messages().send ("sendmail@mail-291708.iam.gserviceaccount.com", message).execute();


        } catch (IOException | MessagingException e) {
            e.printStackTrace ();
        }
        
        return null;
    }

    private Message createMessageWithEmail (MimeMessage emailContent) throws IOException, MessagingException {

        ByteArrayOutputStream buffer = new ByteArrayOutputStream();
        emailContent.writeTo(buffer);
        byte[] bytes = buffer.toByteArray();
        String encodedEmail = Base64.encodeBase64URLSafeString(bytes);
        Message message = new Message ();
        message.setRaw(encodedEmail);
        return message;
    }

    public static MimeMessage createEmail(String to, String from, String subject, String bodyText) throws MessagingException {

        Properties props = new Properties ();
        Session session = Session.getDefaultInstance(props, null);

        MimeMessage email = new MimeMessage(session);

        email.setFrom(new InternetAddress (from));
        email.addRecipient(javax.mail.Message.RecipientType.TO,
                new InternetAddress(to));
        email.setSubject(subject);
        email.setText(bodyText);
        return email;
    }
}

我也不确定：

1. 我应该获得哪些凭据？我认为它是ServiceAccountCredentials，但documentation 说要使用GoogleCredential，它已被弃用，所以我尝试了GoogleCredentials

2. 我应该使用哪个电子邮件地址作为发件人 - gmail？服务帐户？ “我”？有两个地方我应该使用它

3. 我应该如何处理令牌？

4. 在 Google Api 控制台顶部显示“您的免费试用正在等待：立即激活...” - 我必须激活帐户才能使用 api？我不这么认为，但不确定

Answer 1

我会尽量回答你的多个问题

1. 不，您不需要 G Suite 帐户即可使用 Gmail API，您可以使用普通 gmail 帐户。

2. 您链接的指南很好，只是认为在应用程序或控制台中，API 使用 REST 架构处理 HTTPs 请求，因此您可以在任何支持 HTTP 请求的平台中使用 API。

3. 最后一点很大程度上取决于您使用的架构，并考虑到我不是 Android 专家。但是“困难”的部分将是获得用户的授权，但我相信你可以正常使用Java。

有用的链接

• G Suite for Android
• Google Services sample
• Authenticate OAuth2 in Android
• JAVA Gmail API quicsktart

Answer 2

初始步骤：

1. 您需要使用您的 Google 帐户登录网络浏览器。

   如果不这样做，您将收到重定向错误错误 400 等。

2. 将应用添加到谷歌云平台， 为您将使用的所有签名添加 sha-1 密钥

3. 创建一个带有讨厌的重定向 URL 的网络应用程序！

最终的控制台将如下所示：

4. 下载 网络应用 credential.json。将其放入新文件夹 app/resources

   Gmail 类快速入门 {

   private static final String APPLICATION_NAME = "com.emable.getlabels" ; 
   private static final JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();
   private static final String TOKENS_DIRECTORY_PATH = "tokens";
   
   /**
    * Global instance of the scopes required by this quickstart.
    * If modifying these scopes, delete your previously saved tokens/ folder.
    */
   
   private static final List<String> SCOPES = Collections.singletonList( GmailScopes.GMAIL_LABELS ) ;
   private static final String CREDENTIALS_FILE_PATH = "/credentials.json";
   
   
   
   public static Message sendMessage(Gmail service,
                                     String userId,
                                     MimeMessage emailContent)
           throws MessagingException, IOException {
       Message message = createMessageWithEmail(emailContent);
       message = service.users().messages().send(userId, message).execute();
   
       System.out.println("Message id: " + message.getId());
       System.out.println(message.toPrettyString());
       return message;
   }
   
    public static Message createMessageWithEmail(MimeMessage emailContent)
            throws MessagingException, IOException {
        ByteArrayOutputStream buffer = new ByteArrayOutputStream();
        emailContent.writeTo(buffer);
        byte[] bytes = buffer.toByteArray();
        String encodedEmail = Base64.encodeBase64URLSafeString(bytes);
        Message message = new Message();
        message.setRaw(encodedEmail);
        return message;
    }
   
   private static LocalServerReceiver localServerReceiver = null;
   private static AuthorizationCodeInstalledApp localAuthorizationCodeInstalledApp = null;
   
   private static Credential getCredentials(final NetHttpTransport HTTP_TRANSPORT,Context context, String personId) throws IOException {
       // Load client secrets.
       InputStream in = GmailQuickstart.class.getResourceAsStream(CREDENTIALS_FILE_PATH);
       if (in == null) {
           throw new FileNotFoundException("Resource not found: " + CREDENTIALS_FILE_PATH);
       }
   
       GoogleClientSecrets clientSecrets = GoogleClientSecrets.load(JSON_FACTORY, new InputStreamReader(in));
   
       // Build flow and trigger user authorization request.
       GoogleAuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(
               HTTP_TRANSPORT, JSON_FACTORY, clientSecrets, SCOPES)
               .setDataStoreFactory(new FileDataStoreFactory(  context.getFilesDir() )) // new java.io.File(TOKENS_DIRECTORY_PATH)))
               .setAccessType("online")
               .setApprovalPrompt("force")
               .build();
        if (localServerReceiver == null) {
            localServerReceiver = new LocalServerReceiver.Builder().setPort(8888).build();
        }else{
            localServerReceiver.stop();
            localServerReceiver = new LocalServerReceiver.Builder().setPort(8888).build();
        }
   
       AuthorizationCodeInstalledApp  lAuthorizationCodeInstalledApp = new AuthorizationCodeInstalledApp(flow, localServerReceiver) {
               protected void onAuthorization(AuthorizationCodeRequestUrl authorizationUrl) throws IOException {
                   String url = (authorizationUrl.build());
                   Intent browserIntent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
                   (context).startActivity(browserIntent);
               }
           };
   
       return lAuthorizationCodeInstalledApp.authorize("user");
   }
   
   public static void start(Context c,String personId, TextView tview) throws IOException, GeneralSecurityException {
       // Build a new authorized API client service.
   
       final NetHttpTransport HTTP_TRANSPORT = new com.google.api.client.http.javanet.NetHttpTransport();
   
       Gmail service = new Gmail.Builder(HTTP_TRANSPORT, JSON_FACTORY,  getCredentials(HTTP_TRANSPORT, c, personId))
               .setApplicationName(APPLICATION_NAME)
               .build();
       new Handler(Looper.getMainLooper()).post(new Runnable() {
           @Override
           public void run() {
               Toast toast = Toast.makeText(c,"Gmail service ok", Toast.LENGTH_SHORT);
               toast.show();
           }
       });
       Log.i("TAG", "BLA");
       // Print the labels in the user's account.
       String userid = "me";
       ListLabelsResponse listResponse = service.users().labels().list(userid).execute();
       List<Label> labels = listResponse.getLabels();
       //service.
       if (labels.isEmpty()) {
           Log.i("TAG","  No Labels ");
   
       } else {
   
           for (Label label : labels) {
               new Handler(Looper.getMainLooper()).post(new Runnable() {
                   @Override
                   public void run() {
                       Toast toast = Toast.makeText(c, label.toString(), Toast.LENGTH_SHORT);
                       toast.show();
                   }
               });
           }
       }
   }
   

这个函数可以通过例如 Avtivity 中的按钮调用。

   public void SendEmailTest(Context context){

       AsyncTask<Void, Void, String> asyncTask = new AsyncTask<Void, Void, String>() {
           @Override
           protected String doInBackground(Void... params) {
               try {
                   try {
                      // ignore personId, tview your dont  really need them
                       GmailQuickstart.start(context, personId, tview);
                   } catch (IOException e) {
                       e.printStackTrace();
                   } catch (GeneralSecurityException e) {
                       e.printStackTrace();
                   }
               } catch (Exception e) {
                   e.printStackTrace();
               }
               return "";

           };

       };
       asyncTask.execute();





   }

添加用户权限：

<uses-permission android:name="android.permission.GET_ACCOUNTS" />
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.READ_SMS"/>
<uses-permission android:name="android.permission.RECEIVE_SMS" />
<uses-permission android:name="android.permission.SMS_RECEIVED" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="com.android.vending.BILLING" />

分级：

plugins {
    id 'com.android.application'
}

android {
    compileSdkVersion 30
    buildToolsVersion "30.0.3"
    repositories {
        google()
    }
    defaultConfig {
        applicationId "      bla bla bla bla bla your app id here"
        minSdkVersion 16
        targetSdkVersion 30
        versionCode 2
        versionName "1.0"
        multiDexEnabled true


        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

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

}




dependencies {

    implementation 'androidx.multidex:multidex:2.0.1'



    def billing_version = "4.0.0"

    implementation 'androidx.appcompat:appcompat:1.3.0'
    implementation 'com.google.android.material:material:1.4.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
    implementation 'com.google.android.gms:play-services-auth:19.2.0'
    implementation 'androidx.navigation:navigation-fragment:2.3.0'
    implementation 'androidx.navigation:navigation-ui:2.3.0'
    debugImplementation files('app/libs')
    debugImplementation fileTree(dir: 'libs', include: ['*.aar', '*.jar'], exclude: [])
    implementation fileTree(dir: 'libs', include: ['*.aar', '*.jar'], exclude: [])
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
    implementation "com.android.billingclient:billing:$billing_version"

    implementation 'com.google.api-client:google-api-client:1.23.0'
    implementation 'com.google.oauth-client:google-oauth-client-jetty:1.23.0'
    implementation 'com.google.apis:google-api-services-gmail:v1-rev83-1.23.0'




}

将 GmailScopes.GMAIL_LABELS 更改为 what ever 上帝帮助我们所有人