Question

使用Java httpClient时，我试图设置主机头。我发现可以使用setVirtualHost在apache httpClient中完成。我该如何使用Java httpClient做同样的事情。

Answer 1

如果发送请求，则会自动设置主机头。以下程序向GET发送httpbin.org/headers请求，并显示到达服务器端的标头。

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

public class Test {

    public static void main(String[] args) throws Exception {
        HttpClient client = HttpClient.newHttpClient();

        HttpRequest request = HttpRequest.newBuilder()
                .uri(new URI("http://httpbin.org/headers"))
                .GET()
                .build();

        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
        System.out.println(response.body());
    }

}

该程序的输出为

{
  "headers": {
    "Content-Length": "0", 
    "Host": "httpbin.org", 
    "Http2-Settings": "AAEAAEAAAAIAAAABAAMAAABkAAQBAAAAAAUAAEAA", 
    "Upgrade": "h2c", 
    "User-Agent": "Java-http-client/11.0.2", 
    "X-Amzn-Trace-Id": "Root=1-5e89b28a-7028ca70c49af58d120493b1"
  }
}

您可以通过定义另一个URI来更改Host字段的值，例如如果使用URI http://www.httpbin.org/headers，则Host标头字段的值为www.httpbin.org。

Host标头不能单独设置。在类jdk.internal.net.http.common.Utils中定义了一组不允许的标头。

private static final Set<String> DISALLOWED_HEADERS_SET;

static {
    // A case insensitive TreeSet of strings.
    TreeSet<String> treeSet = new TreeSet<>(String.CASE_INSENSITIVE_ORDER);
    treeSet.addAll(Set.of("connection", "content-length",
            "date", "expect", "from", "host", "upgrade", "via", "warning"));
    DISALLOWED_HEADERS_SET = Collections.unmodifiableSet(treeSet);
}

在Java httpClient中设置主机头

1 个答案: