如何在 HttpClient 的请求中添加、设置和获取 Header？答案

【问题标题】：How to add,set and get Header in request of HttpClient?如何在 HttpClient 的请求中添加、设置和获取 Header？
【发布时间】：2012-11-24 10:59:13
【问题描述】：

在我的应用程序中，我需要在请求中设置标头，并且需要在控制台中打印标头值... 所以请举一个例子来做这个 HttpClient 或在我的代码中编辑这个......

我的代码是，

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;

public class SimpleHttpPut { 
  public static void main(String[] args) {
    HttpClient client = new DefaultHttpClient();
    HttpPost post = new HttpPost("http://http://localhost:8089/CustomerChatSwing/JoinAction");
    try {
      List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(1);
      nameValuePairs.add(new BasicNameValuePair("userId",
      "123456789"));
      post.setEntity(new UrlEncodedFormEntity(nameValuePairs));

      HttpResponse response = client.execute(post);
      BufferedReader rd = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
      String line = "";
      while ((line = rd.readLine()) != null) {
    System.out.println(line);
      }

    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}

提前谢谢...

【问题讨论】：

如果您想为所有请求设置特定的标头，那么您可以在客户端上设置它们，而不是请求：stackoverflow.com/questions/18707676/…

标签： java http servlets httpclient apache-httpclient-4.x

【解决方案1】：

可以使用HttpPost，有一些方法可以在Request中添加Header。

DefaultHttpClient httpclient = new DefaultHttpClient();
String url = "http://localhost";
HttpPost httpPost = new HttpPost(url);

httpPost.addHeader("header-name" , "header-value");

HttpResponse response = httpclient.execute(httpPost);

【讨论】：

DefaultHttpClient 已弃用
CloseableHttpClient 正在使用中。

【解决方案2】：

在 apache 页面上：http://hc.apache.org/httpcomponents-client-ga/tutorial/html/fundamentals.html

你有这样的东西：

URIBuilder builder = new URIBuilder();
builder.setScheme("http").setHost("www.google.com").setPath("/search")
    .setParameter("q", "httpclient")
    .setParameter("btnG", "Google Search")
    .setParameter("aq", "f")
    .setParameter("oq", "");
URI uri = builder.build();
HttpGet httpget = new HttpGet(uri);
System.out.println(httpget.getURI());

【讨论】：

【解决方案3】：

您可以完全按照使用公共 GitHub API 的方式测试此代码（不要超出请求限制）：

public class App {

    public static void main(String[] args) throws IOException {

        CloseableHttpClient client = HttpClients.custom().build();

        // (1) Use the new Builder API (from v4.3)
        HttpUriRequest request = RequestBuilder.get()
                .setUri("https://api.github.com")
                // (2) Use the included enum
                .setHeader(HttpHeaders.CONTENT_TYPE, "application/json")
                // (3) Or your own
                .setHeader("Your own very special header", "value")
                .build();

        CloseableHttpResponse response = client.execute(request);

        // (4) How to read all headers with Java8
        List<Header> httpHeaders = Arrays.asList(response.getAllHeaders());
        httpHeaders.stream().forEach(System.out::println);

        // close client and response
    }
}

【讨论】：