手机上的Gmail附加组件中没有显示通用操作。

要在手机上的Gmail附加组件中显示通用操作，可以使用Gmail API和Android开发进行自定义开发。下面是一个示例解决方案：

1. 首先，确保已设置好Gmail API。请参考Gmail API文档进行设置。

2. 创建一个Android项目，添加所需的依赖项。在build.gradle文件中添加以下依赖项：

implementation 'com.google.api-client:google-api-client:1.30.9'
implementation 'com.google.api-client:google-api-client-android:1.30.9'
implementation 'com.google.apis:google-api-services-gmail:v1-rev110-1.30.9'
implementation 'com.google.android.gms:play-services-auth:19.2.0'

3. 在Android项目中创建一个GmailUtils类，用于管理Gmail API的调用。示例代码如下：

import android.content.Context;
import android.os.AsyncTask;
import com.google.api.client.extensions.android.http.AndroidHttp;
import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
import com.google.api.client.googleapis.extensions.android.gms.auth.GoogleAccountCredential;
import com.google.api.client.googleapis.util.Utils;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.JsonObjectParser;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.client.util.ExponentialBackOff;
import com.google.api.services.gmail.Gmail;
import com.google.api.services.gmail.GmailScopes;
import com.google.api.services.gmail.model.ListMessagesResponse;
import com.google.api.services.gmail.model.Message;

import java.io.IOException;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

public class GmailUtils {
    private static final String[] SCOPES = {GmailScopes.GMAIL_MODIFY};
    private static final String APPLICATION_NAME = "Gmail API Android";
    private static final JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();

    private GoogleAccountCredential credential;
    private Gmail gmailService;

    public GmailUtils(Context context) {
        credential = GoogleAccountCredential
                .usingOAuth2(context, Collections.singletonList(GmailScopes.GMAIL_MODIFY))
                .setBackOff(new ExponentialBackOff());

        // TODO: add your Google API project credentials
        // credential.setSelectedAccountName("your-account-name");

        gmailService = new Gmail.Builder(
                AndroidHttp.newCompatibleTransport(),
                JSON_FACTORY,
                credential)
                .setHttpRequestInitializer(credential)
                .setApplicationName(APPLICATION_NAME)
                .build();
    }

    public void listMessages() {
        new AsyncTask<Void, Void, List<Message>>() {
            @Override
            protected List<Message> doInBackground(Void... voids) {
                try {
                    String user = "me";
                    ListMessagesResponse response = gmailService.users().messages().list(user).execute();
                    return response.getMessages();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                return null;
            }

            @Override
            protected void onPostExecute(List<Message> messages) {
                // handle the list of messages
            }
        }.execute();
    }
}

4. 在你的Activity中使用GmailUtils类来调用Gmail API。示例代码如下：

import android.Manifest;
import android.accounts.AccountManager;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.View;
import android.widget.Button;
import androidx.appcompat.app.AppCompatActivity;
import com.google.android.gms.common.AccountPicker;
import pub.devrel.easypermissions.AfterPermissionGranted;
import pub.devrel.easypermissions.EasyPermissions;

public class MainActivity extends AppCompatActivity {
    private static final int REQUEST_ACCOUNT_PICKER = 1000;
    private static final int REQUEST_PERMISSION_GET_ACCOUNTS = 1001;

    private Button button;

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

        button = findViewById(R.id.button);

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                getResultsFromApi();
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == REQUEST_ACCOUNT_PICKER && resultCode == RESULT_OK) {
            String accountName = data.getStringExtra(AccountManager.KEY_ACCOUNT_NAME);
            if (accountName != null) {
                SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(this);
                SharedPreferences.Editor editor = settings.edit();
                editor.putString("accountName", accountName);
                editor.apply();
                getResultsFromApi();
            }
        }
    }

    @AfterPermissionGranted