HTTPClient相关问题

1. 什么是httpClient?

HttpClient 是Apache Jakarta Common 下的子项目，可以用来提供高效的、最新的、功能丰富的支持 HTTP 协议的用户端编程工具包，并且它支持 HTTP 协议最新的版本和建议。

2. 什么是HttpClient不能做的?

· HttpClient不是浏览器，它是一个用户端 http协议传输类库。

· HttpClient被用来发送和接受Http消息。

· HttpClient会解决 http消息的内容，不会进行 javascript解析，不会关心content type，假如没有明确设置，httpclient也不会对请求进行格式化、重定向 url，或者者其余任何和

· http 消息传输相关的功能。

3. HttpClient有哪些特性？

· 实现了所有 HTTP 的方法（GET,POST,PUT,HEAD 等）

· 支持自动转向

· 支持 HTTPS 协议

· 支持代理商服务器等

4. HttpClient怎么发送带参数的GET请求？

引入依赖


 org.apache.httpcomponents
 httpcore
 4.4.6
 
 
 org.apache.httpcomponents
 httpclient
 4.5.3

简单的get和post请求

public static void main(String[] args) throws Exception{
 try {
 //此为百度一篇文章
 String url = "https://mbd.baidu.com/newspage/data/landingsuper?context=%7B%22nid%22%3A%22news_15984470154821203735%22%7D&amp;n_type=0&amp;p_from=1";
 // 使用默认配置创立httpclient的实例
 CloseableHttpClient client = HttpClients.createDefault();
// HttpPost post = new HttpPost(url);
 HttpGet get = new HttpGet(url);
// CloseableHttpResponse response = client.execute(post);
 CloseableHttpResponse response = client.execute(get);
 // 服务器返回码
 System.out.println(response.getStatusLine().toString());
 System.out.println(response.getStatusLine().getStatusCode());
 System.out.println(response.getStatusLine().getReasonPhrase());
 // 服务器返回内容
 String respStr = null;
 HttpEntity entity = response.getEntity();
 if(entity != null) {
 respStr = EntityUtils.toString(entity, "UTF-8");
 }
 System.out.println("respStr = " + respStr);
 // 释放资源
 EntityUtils.consume(entity);
 } catch (Exception e) {
 e.printStackTrace();
 }
 }

5. HttpClient怎么发送带参数的POST请求？

public static void main(String[] args) { 
try { 
String url = "http://localhost:9090"; // 使用默认配置创立httpclient的实例 CloseableHttpClient client = HttpClients.createDefault(); HttpPost post = new HttpPost(url); /** * 设置参数，常用的有StringEntity,UrlEncodedFormEntity,MultipartEntity * 具体看org.apache.http.entity包 */
List params = new ArrayList<>(); 
params.add(new BasicNameValuePair("username", "张三")); 
params.add(new BasicNameValuePair("password", "123456")); 
UrlEncodedFormEntity e = new UrlEncodedFormEntity(params, "UTF-8"); 
post.setEntity(e); 
CloseableHttpResponse response = client.execute(post); // 服务器返回码 
int status_code = response.getStatusLine().getStatusCode(); System.out.println(status_code); // 服务器返回内容 
String respStr = null; 
HttpEntity entity = response.getEntity(); 
if(entity != null) { 
respStr = EntityUtils.toString(entity, "UTF-8"); 
} 
System.out.println("respStr = " + respStr); // 释放资源 
EntityUtils.consume(entity); 
} catch (Exception e) { 
e.printStackTrace(); 
}
}

6. HttpClient怎么获取响应状态？

int StatusCode = httpResponse.getStatusLine().getStatusCode();

7. HttpClient怎么获取响应内容？

HttpEntity httpEntity = response.getEntity();
 if (httpEntity != null) {
 System.out.println("长度：\t" + httpEntity.getContentLength());
 System.out.println("内容：\t" + EntityUtils.toString(httpEntity,"UTF-8"));
 }

8. HttpClient怎么上传文件？

String uploadUrl = "http://localhost:9102/upload.do"; 
HttpPost httpPost = new HttpPost(uploadUrl); 
FileBody fileBody = new FileBody(new File("C:/Users/Administrator/Desktop/timg.jpg")); MultipartEntityBuilder multipartEntityBuilder = MultipartEntityBuilder.create(); multipartEntityBuilder.addPart("file",fileBody); 
// 设置其余参数 
List nvps = new ArrayList(); 
nvps.add(new NameValuePair("Accept","application/json, text/plain, */*")); nvps.add(new NameValuePair("Accept-Encoding","gzip, deflate, br")); 
nvps.add(new NameValuePair("Accept-Language","zh-CN,zh;q=0.9")); 
nvps.add(new NameValuePair("Connection","keep-alive")); 
nvps.add(new NameValuePair("Content-Length","28700")); 
nvps.add(new NameValuePair("Content-Type","multipart/form-data; boundary=----WebKitFormBoundarypaEfQmIQBbUrkI0c")); 
nvps.add(new NameValuePair("Host","localhost:9102")); 
nvps.add(new NameValuePair("Origin","http://localhost:9102")); 
nvps.add(new NameValuePair("Referer","http://localhost:9102/admin/goods_edit.html")); nvps.add(new NameValuePair("User-Agent","Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.146 Safari/537.36")); HttpEntity reqEntity = multipartEntityBuilder.build(); 
httpPost.setEntity(reqEntity);
CloseableHttpResponse response = httpClient.execute(httpPost);

来自：《Java网络编程面试题》

出版单位：北京尚学堂优效学院

优效学院由清华大学著名的IT教育领导者马士兵老师创办，是一家线上线下相互融合的互联网+培训机构。公司均由海外留学生和国内行业精英人士担任授课讲师，主要成员均硕士且拥有十多年的行业经验。毕业学生就职于国内BAT以及海外著名公司。优效学院，名师执教，高效学习，成就未来。

著：张洋

优效学院_张洋老师
11年工作经验曾就职联众游戏(程序员)、众信旅游(Team Leader)、精智教育(联合创始人)、中国石化(大数据高级顾问) 精通javaEE体系、互联网产品架构，熟习Sap Bw/HANA、多个大数据项目经验。

20180926版