PHP对接Amazon Product Advertising API触发FATAL ERROR求助

问题描述 #

近几日尝试使用PHP对接Amazon Product Advertising API，先后测试了SDK与非SDK两种对接方式均无法正常调用。运行非SDK实现代码时触发PHP FATAL ERROR，报错信息如下：

root@difmode:/var/www/html/cms# php index.php
PHP Fatal error: Uncaught Exception: Exception Occured in /var/www/html/cms/index.php:56
Stack trace:
#0 {main}
thrown in /var/www/html/cms/index.php on line 56

故障代码 #

<?php

/**
 * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * or in the "license" file accompanying this file. This file is distributed
 * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */
include ("aws.php");
$searchItemRequest = new SearchItemsRequest ();
$searchItemRequest->PartnerType = "Associates";
// Put your Partner tag (Store/Tracking id) in place of Partner tag
$searchItemRequest->PartnerTag = "***";
$searchItemRequest->Keywords = "Harry";
$searchItemRequest->SearchIndex = "All";
$searchItemRequest->Resources = ["Images.Primary.Small","ItemInfo.Title","Offers.Listings.Price"];
$host = "webservices.amazon.com";
$path = "/paapi5/searchitems";
$payload = json_encode ($searchItemRequest);
//Put your Access Key in place of <ACCESS_KEY> and Secret Key in place of <SECRET_KEY> in double quotes
$awsv4 = new AwsV4 ("***", "***");
$awsv4->setRegionName("us-east-1");
$awsv4->setServiceName("ProductAdvertisingAPI");
$awsv4->setPath ($path);
$awsv4->setPayload ($payload);
$awsv4->setRequestMethod ("POST");
$awsv4->addHeader ('content-encoding', 'amz-1.0');
$awsv4->addHeader ('content-type', 'application/json; charset=utf-8');
$awsv4->addHeader ('host', $host);
$awsv4->addHeader ('x-amz-target', 'com.amazon.paapi5.v1.ProductAdvertisingAPIv1.SearchItems');
$headers = $awsv4->getHeaders ();
$headerString = "";
foreach ( $headers as $key => $value ) {
    $headerString .= $key . ': ' . $value . "\r\n";
}
$params = array (
        'http' => array (
            'header' => $headerString,
            'method' => 'POST',
            'content' => $payload
        )
    );
$stream = stream_context_create ( $params );

$fp = @fopen ( 'https://'.$host.$path, 'rb', false, $stream );

if (! $fp) {
    throw new Exception ( "Exception Occured" );
}
$response = @stream_get_contents ( $fp );
if ($response === false) {
    throw new Exception ( "Exception Occured" );
}
echo $response;

class SearchItemsRequest {
    public $PartnerType;
    public $PartnerTag;
    public $Keywords;
    public $SearchIndex;
    public $Resources;
}
?>

故障排查&解决方案 #

你代码里用@符号压制了fopen和流读取的所有错误信息，导致看不到实际的请求失败原因，先把两处@删掉重新运行，就能拿到具体的接口返回错误。常见的触发56行报错的原因有以下几种：

• 配置参数错误：检查替换的Access Key、Secret Key、PartnerTag是否和亚马逊联盟后台的配置完全一致，不要多打空格或特殊字符
• 区域不匹配：如果你的亚马逊联盟账号对应区域不是美国站，需要把$host和setRegionName的值改成对应区域的配置，比如日本站host要改成webservices.amazon.co.jp，region改成us-west-2
• 签名生成错误：检查aws.php里的AwsV4类是否完整，签名算法是否符合PAAPI 5.0要求，常见错误是加密时漏加服务名、区域名参数
• 网络连通问题：检查运行代码的服务器是否能正常访问webservices.amazon.com，可以直接在服务器上执行curl https://webservices.amazon.com/paapi5/searchitems测试连通性，国内服务器大概率会因为网络问题无法请求亚马逊接口
• PHP配置问题：检查php.ini是否开启了allow_url_fopen，如果未开启fopen无法发起HTTP请求，改成开启状态或者用curl重写请求逻辑即可

内容的提问来源于stack exchange，提问作者iam_mine