Apache HttpClient - Http 获取请求
GET 方法用于使用给定 URI 从给定服务器检索信息。使用 GET 的请求应该只检索数据，而不应该对数据产生其他影响。
HttpClient API 提供了一个名为HttpGet的类，它表示 get 请求方法。
按照下面给出的步骤使用 HttpClient 库发送 get 请求
第 1 步 - 创建 HttpClient 对象
HttpClients类的createDefault ()方法返回一个CloseableHttpClient对象，它是HttpClient接口的基本实现。
使用此方法，创建一个 HttpClient 对象，如下所示 -
CloseableHttpClient httpclient = HttpClients.createDefault();
第 2 步 - 创建 HttpGet 对象
HttpGet类表示 HTTPGET 请求，该请求使用 URI 检索给定服务器的信息。
通过实例化此类来创建 HTTP GET 请求。此类的构造函数接受表示 URI 的字符串值。
HttpGet httpget = new HttpGet("https://www.tutorialspoint.com/");
第 3 步 - 执行获取请求
CloseableHttpClient类的execute ()方法接受HttpUriRequest（接口）对象（即HttpGet、HttpPost、HttpPut、HttpHead 等）并返回响应对象。
使用此方法执行请求，如下所示 -
HttpResponse httpresponse = httpclient.execute(httpget);
例子
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());
}
}
}
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>