Apache HttpClient - Http 获取请求

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GET 方法用于使用给定的 URI 从给定的服务器检索信息。使用 GET 的请求应只检索数据，不得对数据产生任何其他影响。

HttpClient API 提供了一个名为 HttpGet 的类，它表示 get 请求方法。

按照以下步骤发送使用 HttpClient 库的 get 请求

步骤 1 - 创建一个 HttpClient 对象

HttpClients 类的 createDefault() 方法返回一个 CloseableHttpClient 对象，它就是 HttpClient 接口的基本实现。

使用此方法，如下所示创建 HttpClient 对象 −

CloseableHttpClient httpclient = HttpClients.createDefault();

步骤 2 - 创建一个 HttpGet 对象

HttpGet 类表示 HTTPGET 请求，它使用 URI 检索给定服务器的信息。

通过实例化此类创建 HTTP GET 请求。此类的构造函数接受一个表示 URI 的字符串值。

HttpGet httpget = new HttpGet("https://tutorialspoint.com/");

步骤 3 - 执行获取请求

CloseableHttpClient 类的 execute() 方法接受一个 HttpUriRequest（接口）对象（即 HttpGet、HttpPost、HttpPut、HttpHead 等），并返回一个响应对象。

使用此方法执行请求，如下所示 −

HttpResponse httpresponse = httpclient.execute(httpget);

示例

以下是演示使用 HttpClient 库执行 HTTP GET 请求的一个示例。

import java.util.Scanner;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

public class HttpGetExample {
 
   public static void main(String args[]) throws Exception{
 
      //Creating a HttpClient object
      CloseableHttpClient httpclient = HttpClients.createDefault();

      //Creating a HttpGet object
      HttpGet httpget = new HttpGet("https://tutorialspoint.com/ ");

      //Printing the method used
      System.out.println("Request Type: "+httpget.getMethod());

      //Executing the Get request
      HttpResponse httpresponse = httpclient.execute(httpget);

      Scanner sc = new Scanner(httpresponse.getEntity().getContent());

      //Printing the status line
      System.out.println(httpresponse.getStatusLine());
      while(sc.hasNext()) {
         System.out.println(sc.nextLine());
      }
   }
}

输出

上述程序生成以下输出 −

Request Type: GET
<!DOCTYPE html>
<!--[if IE 8]><html class = "ie ie8"> <![endif]-->
<!--[if IE 9]><html class = "ie ie9"> <![endif]-->
<!--[if gt IE 9]><!-->
<html lang = "en-US"> <!--<![endif]-->
<head>
<!-- Basic -->
<meta charset = "utf-8">
<title>Parallax Scrolling, Java Cryptography, YAML, Python Data Science, Java
i18n, GitLab, TestRail, VersionOne, DBUtils, Common CLI, Seaborn, Ansible,
LOLCODE, Current Affairs 2018, Apache Commons Collections</title>
<meta name = "Description" content = "Parallax Scrolling, Java Cryptography, YAML,
Python Data Science, Java i18n, GitLab, TestRail, VersionOne, DBUtils, Common
CLI, Seaborn, Ansible, LOLCODE, Current Affairs 2018, Intellij Idea, Apache
Commons Collections, Java 9, GSON, TestLink, Inter Process Communication (IPC),
Logo, PySpark, Google Tag Manager, Free IFSC Code, SAP Workflow"/>
<meta name = "Keywords" content = "Python Data Science, Java i18n, GitLab,
TestRail, VersionOne, DBUtils, Common CLI, Seaborn, Ansible, LOLCODE, Gson,
TestLink, Inter Process Communication (IPC), Logo"/>
<meta http-equiv = "X-UA-Compatible" content = "IE = edge">
<meta name = "viewport" content = "width = device-width,initial-scale = 1.0,userscalable = yes">
<link href = "https://cdn.muicss.com/mui-0.9.39/extra/mui-rem.min.css"
rel = "stylesheet" type = "text/css" />
<link rel = "stylesheet" href="/questions/css/home.css?v = 3" />
<script src = "/questions/js/jquery.min.js"></script>
<script src = "/questions/js/fontawesome.js"></script>
<script src = "https://cdn.muicss.com/mui-0.9.39/js/mui.min.js"></script>
</head>
. . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . .
</script>
</body>
</html>
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