当Google登录客户端始终返回RESULT_CANCELED时，可能是由于以下几个原因：

1. 未正确配置Google登录的OAuth 2.0客户端凭据。
2. 未正确处理ActivityResult。

下面是一种解决方法的示例代码：

首先，在您的Android项目的build.gradle文件中添加以下依赖项：

implementation 'com.google.android.gms:play-services-auth:19.2.0'

接下来，在您的Activity中，添加以下代码：

import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;

import com.google.android.gms.auth.api.Auth;
import com.google.android.gms.auth.api.credentials.Credential;
import com.google.android.gms.auth.api.credentials.CredentialRequest;
import com.google.android.gms.auth.api.credentials.CredentialRequestResult;
import com.google.android.gms.auth.api.credentials.CredentialsOptions;
import com.google.android.gms.auth.api.credentials.HintRequest;
import com.google.android.gms.auth.api.credentials.IdentityProviders;
import com.google.android.gms.auth.api.credentials.IdentityProviders;
import com.google.android.gms.auth.api.credentials.IdToken;
import com.google.android.gms.auth.api.credentials.PasswordSpecification;
import com.google.android.gms.auth.api.credentials.CredentialPickerConfig;

public class LoginActivity extends AppCompatActivity {
    private static final int RC_HINT = 1001;
    private static final int RC_SIGN_IN = 1002;
    private static final String TAG = "LoginActivity";

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

        // 在适当的位置调用请求凭据的方法
        requestCredentials();
    }

    private void requestCredentials() {
        CredentialRequest credentialRequest = new CredentialRequest.Builder()
                .setPasswordLoginSupported(true)
                .setAccountTypes(IdentityProviders.GOOGLE)
                .build();

        Auth.CredentialsApi.request(this, credentialRequest).setResultCallback(
                new ResultCallback() {
                    @Override
                    public void onResult(@NonNull CredentialRequestResult credentialRequestResult) {
                        if (credentialRequestResult.getStatus().isSuccess()) {
                            // 凭据请求成功
                            Credential credential = credentialRequestResult.getCredential();
                            // 使用凭据进行登录
                            signInWithCredential(credential);
                        } else {
                            // 凭据请求被取消或出现错误
                            Log.e(TAG, "Credential request failed: " + credentialRequestResult.getStatus());
                        }
                    }
                });
    }

    private void signInWithCredential(Credential credential) {
        // 使用凭据进行登录
        // 这里可以使用凭据中的身份验证信息来进行登录
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if (requestCode == RC_HINT) {
            // 处理凭据提示结果
            if (resultCode == RESULT_OK) {
                // 用户选择了一个凭据
                Credential credential = data.getParcelableExtra(Credential.EXTRA_KEY);
                // 使用凭据进行登录
                signInWithCredential(credential);
            } else {
                // 用户取消了凭据提示
                Log.e(TAG, "Credential hint selection canceled");
            }
        } else if (requestCode == RC_SIGN_IN) {
            // 处理Google登录结果
            // 检查resultCode是否为RESULT_OK
            if (resultCode == RESULT_OK) {
                // Google登录成功
                // 这里可以处理登录成功后的逻辑
            } else {
                // Google登录被取消或出现错误
                Log.e(TAG, "Google sign-in canceled or failed");
            }
        }
    }

    private void requestGoogleSignIn() {
        CredentialsOptions options = new CredentialsOptions.Builder()
                .forceEnableSaveDialog()
                .build();

        HintRequest hintRequest = new HintRequest.Builder()
                .setHintPickerConfig(new CredentialPickerConfig.Builder()
                        .setShowCancelButton(true)
                        .build())
                .setEmailAddressIdentifierSupported(true)
                .setAccountTypes(IdentityProviders.GOOGLE)
                .setCredentialsOptions(options)
                .build();

        PendingIntent intent = Auth.CredentialsApi.getHintPickerIntent(this, hintRequest);

        try {
            startIntentSenderForResult(intent.getIntentSender(), RC_HINT, null, 0, 0, 0);
        } catch (IntentSender.SendIntentException e) {
            Log.e(TAG, "Error starting hint picker intent", e);
        }
    }

    private void requestGoogleSignInWithIdToken()