在使用PHP+elasticsearch的时候出现PHP Fatal error: Uncaught Error: Class "Elasticsearch\ClientBuilder" not found in......

最后在国外的网站找到了答案。原来elasticsearch php的类的文件夹变化了。打开ClientBuilder.php，可以看见内容为：

namespace Elastic\Elasticsearch;

use Elastic\Elasticsearch\Exception\AuthenticationException;

use Elastic\Elasticsearch\Exception\ConfigException;

use Elastic\Elasticsearch\Exception\HttpClientException;

use Elastic\Elasticsearch\Exception\InvalidArgumentException;

全部都是在Elastic这个文件夹内。所以我们将代码修改为

require 'vendor/autoload.php';

use Elastic\Elasticsearch\ClientBuilder;

$builder = Elastic\Elasticsearch\ClientBuilder::create();

$builder->setHosts(array("127.0.0.1:9200"));

$client = $builder->build();

就能够正确地调用class了。