Apache Httpclient 简明教程

Apache HttpClient - Http Get Request

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 的请求应该只检索数据而不应该对数据有其他影响。

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

按照下面的步骤使用 HttpClient 库发送 get 请求

Step 1 - Create a HttpClient object

createDefault() 类的 HttpClients 方法返回 CloseableHttpClient 对象，这是 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();

Step 2 - Create an HttpGet Object

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

通过实例化此类创建 HTTP GET 请求。此类接受表示 URI 的 String 值的构造函数。

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

Step 3 - Execute the Get Request

execute() 类的 CloseableHttpClient 方法接受 HttpUriRequest（接口）对象（即 HttpGet、HttpPost、HttpPut、HttpHead 等）并返回响应对象。

如下所示使用此方法执行请求 −

HttpResponse httpresponse = httpclient.execute(httpget);

Example

以下示例演示了使用 HttpClient 库执行 HTTP GET 请求。

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://www.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());
      }
   }
}

Output

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>