如何在Android Studio的Java项目中实现Google Firebase登录？

以下是可直接运行的Java代码实现，替换你现有空的点击事件逻辑：

package com.example.firebasegoogleauth4;

import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import com.google.android.gms.auth.api.identity.BeginSignInRequest;
import com.google.android.gms.auth.api.identity.Identity;
import com.google.android.gms.auth.api.identity.SignInClient;
import com.google.android.gms.auth.api.identity.SignInCredential;
import com.google.android.gms.common.api.ApiException;
import com.google.firebase.auth.AuthCredential;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.GoogleAuthProvider;

public class MainActivity extends AppCompatActivity {

    private Button btn;
    private SignInClient oneTapClient;
    private BeginSignInRequest signInRequest;
    private static final int REQ_ONE_TAP = 2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        btn = findViewById(R.id.button1);
        
        // 初始化OneTap登录客户端
        oneTapClient = Identity.getSignInClient(this);
        signInRequest = BeginSignInRequest.builder()
                .setGoogleIdTokenRequestOptions(BeginSignInRequest.GoogleIdTokenRequestOptions.builder()
                        .setSupported(true)
                        // 替换为你Firebase项目的Web客户端ID，在Firebase控制台>认证>登录方法>Google中获取
                        .setServerClientId(getString(R.string.default_web_client_id))
                        .setFilterByAuthorizedAccounts(false)
                        .build())
                .setAutoSelectEnabled(true)
                .build();
        
        btn.setOnClickListener(v -> startGoogleSignIn());
    }

    private void startGoogleSignIn() {
        oneTapClient.beginSignIn(signInRequest)
                .addOnSuccessListener(result -> {
                    try {
                        startIntentSenderForResult(
                                result.getPendingIntent().getIntentSender(),
                                REQ_ONE_TAP,
                                null, 0, 0, 0);
                    } catch (Exception e) {
                        Toast.makeText(this, "登录启动失败: " + e.getMessage(), Toast.LENGTH_SHORT).show();
                    }
                })
                .addOnFailureListener(e -> 
                        Toast.makeText(this, "无可用登录账号: " + e.getMessage(), Toast.LENGTH_SHORT).show());
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == REQ_ONE_TAP) {
            try {
                SignInCredential credential = oneTapClient.getSignInCredentialFromIntent(data);
                String idToken = credential.getGoogleIdToken();
                if (idToken != null) {
                    AuthCredential firebaseCredential = GoogleAuthProvider.getCredential(idToken, null);
                    FirebaseAuth.getInstance().signInWithCredential(firebaseCredential)
                            .addOnCompleteListener(task -> {
                                if (task.isSuccessful()) {
                                    Toast.makeText(this, "登录成功", Toast.LENGTH_SHORT).show();
                                    // 登录成功后可跳转主页或处理用户数据
                                } else {
                                    Toast.makeText(this, "登录失败: " + task.getException().getMessage(), Toast.LENGTH_SHORT).show();
                                }
                            });
                }
            } catch (ApiException e) {
                Toast.makeText(this, "认证失败: " + e.getMessage(), Toast.LENGTH_SHORT).show();
            }
        }
    }
}

关键配置检查 #

• 打开strings.xml，添加default_web_client_id字段，值从Firebase控制台认证>登录方法>Google的Web SDK配置中复制client_id。
• 确保Firebase控制台已启用Google登录功能。
• 确认模块级build.gradle中已添加依赖：

  implementation 'com.google.firebase:firebase-auth:22.3.1'
  implementation 'com.google.android.gms:play-services-auth:20.7.0'
  

• 测试前清理项目并重新构建，避免缓存问题。

内容的提问来源于stack exchange，提问作者Shiva Ramlal