$baseUrl = 'http://foo';
$config = array();
$client = new Guzzle\Http\Client($baseUrl, $config);
为 Guzzle 设置默认标头而不将其作为参数传递给每个的新方法是什么$client->post($uri, $headers)？
有$client->setDefaultHeaders($headers)，但已弃用。
setDefaultHeaders is deprecated. Use the request.options array to specify default request options
如果您使用 Guzzle v=6.0.*
$client = new GuzzleHttp\Client(['headers' => ['X-Foo' => 'Bar']]);
阅读文档，还有更多选择。
$client = new Guzzle\Http\Client();
// Set a single header using path syntax
$client->setDefaultOption('headers/X-Foo', 'Bar');
// Set all headers
$client->setDefaultOption('headers', array('X-Foo' => 'Bar'));
看这里：
http://docs.guzzlephp.org/en/5.3/clients.html#request-options
正确，旧方法已被标记为@deprecated。这是为客户端上的多个请求设置默认标头的新建议方法。
// enter base url if needed
$url = "";
$headers = array('X-Foo' => 'Bar');
$client = new Guzzle\Http\Client($url, array(
"request.options" => array(
"headers" => $headers
)
));
如果您使用drupal，这对我有用；
<?php
$url = 'https://jsonplaceholder.typicode.com/posts';
$client = \Drupal::httpClient();
$post_data = $form_state->cleanValues()->getValues();
$response = $client->request('POST', $url, [
'headers' => ['Content-Type' => 'application/x-www-form-urlencoded'],
'form_params' => $post_data,
'verify' => false,
]);
$body = $response->getBody()->getContents();
$status = $response->getStatusCode();
dsm($body);
dsm($status);
要为 Guzzle 客户端设置默认标头（如果将客户端用作多个请求的基础），最好设置一个中间件，该中间件将在每个请求中添加标头。否则，其他请求标头将在新的客户端请求中被覆盖。
例如：
use GuzzleHttp\Client;
use GuzzleHttp\HandlerStack;
use GuzzleHttp\Middleware;
use Psr\Http\Message\RequestInterface;
...
$handler = HandlerStack::create();
$handler->push(Middleware::mapRequest(function (RequestInterface $request) {
return $request->withHeader('Authorization', "Bearer {$someAccessToken}");
}));
$client = new Client([
'base_uri' => 'https://example.com',
'handler' => $handler,
]);