求基于PHP-7+CURL调用Google Shopping API的OAuth2.0完整示例

Got it, let's break this down for you. Since you're working with a backend service (no user-facing frontend), the right OAuth2 flow here is the Service Account JWT Grant—no need for user redirects or $_GET parameters. Below is a complete, pure cURL implementation for PHP 7 that handles both getting an access token and making a request to the Google Shopping API, no official libraries required.

Prerequisites #

Before you start, make sure you have:

• A Google Cloud Service Account key file (JSON format, downloaded from the Google Cloud Console)
• The Google Shopping Content API enabled in your Cloud Project
• Your service account granted the necessary permissions in your Merchant Center account (e.g., "Content API Editor" role)

Step 1: Generate OAuth2 Access Token via JWT #

Service accounts use JSON Web Tokens (JWT) to request access tokens directly from Google's auth endpoint. Here's how to implement this with pure cURL and PHP's openssl functions:

<?php
// Path to your service account JSON key file
$serviceAccountKeyPath = '/path/to/your/service-account-key.json';
$serviceAccountData = json_decode(file_get_contents($serviceAccountKeyPath), true);

// 1. Build JWT Header
$jwtHeader = json_encode([
    'alg' => 'RS256',
    'typ' => 'JWT'
]);

// 2. Build JWT Payload
$issuedAt = time();
$expirationTime = $issuedAt + 3600; // Token expires in 1 hour
$audience = 'https://oauth2.googleapis.com/token';

$jwtPayload = json_encode([
    'iss' => $serviceAccountData['client_email'],
    'scope' => 'https://www.googleapis.com/auth/content',
    'aud' => $audience,
    'iat' => $issuedAt,
    'exp' => $expirationTime
]);

// 3. Encode Header and Payload to Base64URL
function base64UrlEncode($data) {
    return rtrim(strtr(base64_encode($data), '+/', '-_'), '=');
}

$encodedHeader = base64UrlEncode($jwtHeader);
$encodedPayload = base64UrlEncode($jwtPayload);

// 4. Sign the JWT with the service account's private key
$signatureInput = $encodedHeader . '.' . $encodedPayload;
openssl_sign(
    $signatureInput,
    $signature,
    $serviceAccountData['private_key'],
    OPENSSL_ALGO_SHA256
);
$encodedSignature = base64UrlEncode($signature);

// 5. Combine into full JWT
$jwt = $encodedHeader . '.' . $encodedPayload . '.' . $encodedSignature;

// 6. Request access token via cURL
$tokenUrl = 'https://oauth2.googleapis.com/token';
$postData = [
    'grant_type' => 'urn:ietf:params:oauth:grant-type:jwt-bearer',
    'assertion' => $jwt
];

$ch = curl_init($tokenUrl);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($postData));
curl_setopt($ch, CURLOPT_HTTPHEADER, [
    'Content-Type: application/x-www-form-urlencoded'
]);

$tokenResponse = curl_exec($ch);
$httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);

if ($httpCode !== 200) {
    die("Failed to get access token: " . $tokenResponse);
}

$tokenData = json_decode($tokenResponse, true);
$accessToken = $tokenData['access_token'];
echo "Access token obtained: " . $accessToken . "\n";
?>

Step 2: Call Google Shopping API with the Access Token #

Once you have the access token, you can use it to make authenticated requests to the Shopping Content API. Below is an example that fetches a list of products from your Merchant Center account:

<?php
// Your Merchant Center ID (numeric ID, e.g., 123456789)
$merchantId = 'YOUR_MERCHANT_ID';
$apiUrl = "https://shoppingcontent.googleapis.com/content/v2.1/$merchantId/products";

// Set up cURL request
$ch = curl_init($apiUrl);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, [
    "Authorization: Bearer $accessToken",
    'Content-Type: application/json'
]);

// Optional: Add query parameters (e.g., limit results)
curl_setopt($ch, CURLOPT_URL, $apiUrl . '?maxResults=10');

$apiResponse = curl_exec($ch);
$httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);

// Handle response
if ($httpCode === 200) {
    $products = json_decode($apiResponse, true);
    print_r($products);
} else {
    die("API request failed: HTTP $httpCode - " . $apiResponse);
}
?>

Key Notes for Production #

• Cache the Access Token: Tokens are valid for 1 hour, so store it in a cache (e.g., Redis, filesystem) instead of requesting a new one every time.
• Error Handling: Add more robust error handling for cURL failures (e.g., timeouts, connection issues) and API error responses.
• Permissions: Ensure your service account is properly linked to your Merchant Center account (you can do this in Merchant Center > Settings > Users and permissions).
• PHP 7 Compatibility: All functions used here are compatible with PHP 7.0 and above.

内容的提问来源于stack exchange，提问作者Mike Robinson