问如何使用Firebase函数在用户创建后发送电子邮件验证？

EN

const functions = require('firebase-functions');
const fetch = require('node-fetch');

// Send email verification through express server
exports.sendVerificationEmail = functions.auth.user().onCreate((user) => {
  // Example of API ENPOINT URL 'https://mybackendapi.com/api/verifyemail/'
  return fetch( < API ENDPOINT URL > , {
      method: 'POST',
      body: JSON.stringify({
        user: user
      }),
      headers: {
        "Content-Type": "application/json"
      }
    }).then(res => console.log(res))
    .catch(err => console.log(err));
});

// File name 'middleware.js'
import firebase from 'firebase';
import admin from 'firebase-admin';

// Get Service account file from firebase console
// Store it locally - make sure not to commit it to GIT
const serviceAccount = require('<PATH TO serviceAccount.json FILE>');
// Get if from Firebase console and either use environment variables or copy and paste them directly
// review security issues for the second approach
const config = {
  apiKey: process.env.APIKEY,
  authDomain: process.env.AUTHDOMAIN,
  projectId: process.env.PROJECT_ID,
};
// Initialize Firebase Admin
admin.initializeApp({
  credential: admin.credential.cert(serviceAccount),
});

// Initialize firebase Client
firebase.initializeApp(config);

export const verifyEmail = async(req, res, next) => {
  const sentUser = req.body.user;
  try {
    const customToken = await admin.auth().createCustomToken(sentUser.uid);
    await firebase.auth().signInWithCustomToken(customToken);
    const mycurrentUser = firebase.auth().currentUser;
    await mycurrentUser.sendEmailVerification();
    res.locals.data = mycurrentUser;
    next();
  } catch (err) {
    next(err);
  }
};

// Filename 'app.js'
import express from 'express';
import bodyParser from 'body-parser';
// If you don't use cors, the api will reject request if u call it from Cloud functions
import cors from 'cors';
import {
  verifyEmail
} from './middleware'

app.use(cors());
app.use(bodyParser.urlencoded({
  extended: true,
}));
app.use(bodyParser.json());

const app = express();
// If you use the above example for endpoint then here will be
// '/api/verifyemail/'
app.post('<PATH TO ENDPOINT>', verifyEmail, (req, res, next) => {
  res.json({
    status: 'success',
    data: res.locals.data
  });
  next()
})

 private void sendVerification() {
             FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
             user.sendEmailVerification().addOnCompleteListener(new OnCompleteListener<Void>() {
                @Override
                public void onComplete(@NonNull Task<Void> task) {
                    if (task.isSuccessful()) {
                         system.print.out("Verification Email sent Champion")
                          }
                         }
                });
}

 private void checkEmail() {

    FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();

    if (user.isEmailVerified()) {
           // email verified ...
    } else {
       // error : email not verified ...
    }
}