Apache HttpClient POST HTTP请求示例

转x33g5p2x  于2022-10-07 转载在 Apache  
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在这篇快速文章中，我们将逐步讨论如何使用Apache HttpClient 4.5来进行HTTP POST请求。HTTP POST请求方法要求服务器接受请求中所包含的实体作为URI识别的网络资源的一个新的下级。

HttpClient支持HTTP/1.1规范中定义的所有HTTP方法：GET、HEAD、POST、PUT、DELETE、TRACE和OPTIONS。每种方法类型都有一个特定的类：HttpGet、HttpHead、HttpPost、HttpPut、HttpDelete、HttpTrace、和HttpOptions。
在这个例子中，我们将使用HttpPost类来处理POST HTTP方法。查看Apache HttpClient GET HTTP请求实例

使用Apache HttpClient - 添加依赖性

Apache HttpClient库允许处理HTTP请求。要使用这个库，请在你的Maven或Gradle构建文件中添加一个依赖项。你可以在这里找到最新版本：https://mvnrepository.com/artifact/org.apache.httpcomponents/httpclient

我们使用maven来管理我们的依赖关系，并使用Apache HttpClient 4.5版本。在你的项目中添加以下依赖项，以便进行HTTP POST请求方式。

  1. <dependency>
  2.  <groupId>org.apache.httpcomponents</groupId>
  3.  <artifactId>httpclient</artifactId>
  4.  <version>4.5</version>
  5. </dependency>

开发步骤

让我们创建一个逐步的例子，用HttpClient来做一个HTTP POST请求。

1. 使用辅助类HttpClients创建CloseableHttpClient的实例。

  1. CloseableHttpClient httpclient = HttpClients.createDefault()

HttpClients.createDefault()方法以默认配置创建CloseableHttpClient实例。

2. 创建一个基本的POST请求

  1. HttpPost httpPost = new HttpPost("http://localhost:8080/api/v1/users");

3. 为Post HTTP请求添加头信息

  1. HttpPost httpPost = new HttpPost("http://localhost:8080/api/v1/users");
  2. httpPost.setHeader("Accept", "application/json");
  3. httpPost.setHeader("Content-type", "application/json");

3. 在Post请求中添加JSON数据

  1. String json = "{\r\n" + 
  2.   "  \"firstName\": \"Ram\",\r\n" + 
  3.   "  \"lastName\": \"Jadhav\",\r\n" + 
  4.   "  \"emailId\": \"ramesh1234@gmail.com\",\r\n" + 
  5.   "  \"createdAt\": \"2018-09-11T11:19:56.000+0000\",\r\n" + 
  6.   "  \"createdBy\": \"Ramesh\",\r\n" + 
  7.   "  \"updatedAt\": \"2018-09-11T11:26:31.000+0000\",\r\n" + 
  8.   "  \"updatedby\": \"Ramesh\"\r\n" + 
  9.   "}";
  10. StringEntity stringEntity = new StringEntity(json);
  11. httpPost.setEntity(stringEntity);

4. 创建一个自定义的响应处理程序

  1. ResponseHandler < String > responseHandler = response - > {
  2.     int status = response.getStatusLine().getStatusCode();
  3.     if (status >= 200 && status < 300) {
  4.         HttpEntity entity = response.getEntity();
  5.         return entity != null ? EntityUtils.toString(entity) : null;
  6.     } else {
  7.         throw new ClientProtocolException("Unexpected response status: " + status);
  8.     }
  9. };

5. 通过execute()方法发送基本的POST请求

  1. String responseBody = httpclient.execute(httpPost, responseHandler);

HttpClient HTTP POST请求方法实例

让我们来讨论如何在实时项目中使用HttpClient。考虑到我们已经部署了Spring Boot Restful CRUD APIs。请看这篇文章 - Spring Boot 2 + hibernate 5 + CRUD REST API教程。

在下面的例子中，我们发送一个资源给http://localhost:8080/api/v1/users。这个资源接受请求的JSON，对其进行处理并将其存储到数据库中。这个服务还返回一个带有资源的响应。在这个例子中，我们使用Java 7 try-with-resources来自动处理ClosableHttpClient的关闭，我们也使用Java 8 lambdas来处理ResponseHandler。

  1. package com.javadevelopersguide.httpclient.examples;
  3. import java.io.IOException;
  5. import org.apache.http.HttpEntity;
  6. import org.apache.http.client.ClientProtocolException;
  7. import org.apache.http.client.ResponseHandler;
  8. import org.apache.http.client.methods.HttpPost;
  9. import org.apache.http.entity.StringEntity;
  10. import org.apache.http.impl.client.CloseableHttpClient;
  11. import org.apache.http.impl.client.HttpClients;
  12. import org.apache.http.util.EntityUtils;
  14. /**
  15. * This example demonstrates the use of {@link HttpPost} request method.
  16. * @author Ramesh Fadatare
  17. */
  18. public class HttpPostRequestMethodExample {
  20.     public static void main(String[] args) throws IOException {
  21.         postUser();
  22.     }
  24.     public static void postUser() throws IOException {
  25.         try (CloseableHttpClient httpclient = HttpClients.createDefault()) {
  26.             HttpPost httpPost = new HttpPost("http://localhost:8080/api/v1/users");
  27.             httpPost.setHeader("Accept", "application/json");
  28.             httpPost.setHeader("Content-type", "application/json");
  29.             String json = "{\r\n" +
  30.                 "  \"firstName\": \"Ram\",\r\n" +
  31.                 "  \"lastName\": \"Jadhav\",\r\n" +
  32.                 "  \"emailId\": \"ramesh1234@gmail.com\",\r\n" +
  33.                 "  \"createdAt\": \"2018-09-11T11:19:56.000+0000\",\r\n" +
  34.                 "  \"createdBy\": \"Ramesh\",\r\n" +
  35.                 "  \"updatedAt\": \"2018-09-11T11:26:31.000+0000\",\r\n" +
  36.                 "  \"updatedby\": \"Ramesh\"\r\n" +
  37.                 "}";
  38.             StringEntity stringEntity = new StringEntity(json);
  39.             httpPost.setEntity(stringEntity);
  41.             System.out.println("Executing request " + httpPost.getRequestLine());
  43.             // Create a custom response handler
  44.             ResponseHandler < String > responseHandler = response - > {
  45.                 int status = response.getStatusLine().getStatusCode();
  46.                 if (status >= 200 && status < 300) {
  47.                     HttpEntity entity = response.getEntity();
  48.                     return entity != null ? EntityUtils.toString(entity) : null;
  49.                 } else {
  50.                     throw new ClientProtocolException("Unexpected response status: " + status);
  51.                 }
  52.             };
  53.             String responseBody = httpclient.execute(httpPost, responseHandler);
  54.             System.out.println("----------------------------------------");
  55.             System.out.println(responseBody);
  56.         }
  57.     }
  58. }

输出

  1. Executing request POST http://localhost:8080/api/v1/users HTTP/1.1
  2. ----------------------------------------
  3. {"id":37,"firstName":"Ram","lastName":"Jadhav","emailId":"ramesh1234@gmail.com",
  4. "createdAt":"2018-10-29T09:37:09.821+0000","createdBy":"Ramesh","updatedAt":"2018-10-29T09:37:09.821+0000",
  5. "updatedby":"Ramesh"}

更多的例子

在下面的例子中，我们向资源http://httpbin.org/post发布数据。该资源确认数据并返回一个JSON对象，我们将简单地打印到控制台。 

  1. package com.javadevelopersguide.httpclient.examples;
  3. import java.io.IOException;
  5. import org.apache.http.HttpEntity;
  6. import org.apache.http.client.ClientProtocolException;
  7. import org.apache.http.client.ResponseHandler;
  8. import org.apache.http.client.methods.HttpPost;
  9. import org.apache.http.entity.StringEntity;
  10. import org.apache.http.impl.client.CloseableHttpClient;
  11. import org.apache.http.impl.client.HttpClients;
  12. import org.apache.http.util.EntityUtils;
  14. /**
  15. * This example demonstrates the use of {@link HttpPost} request method.
  16. */
  17. public class HttpPostRequestMethodExample {
  19.     public static void main(String[] args) throws IOException {
  20.         post();
  21.     }
  22.     public static void post() throws IOException {
  24.         try (CloseableHttpClient httpclient = HttpClients.createDefault()) {
  25.             HttpPost httpPost = new HttpPost("http://httpbin.org/post");
  26.             httpPost.setEntity(new StringEntity("Hello, World"));
  28.             System.out.println("Executing request " + httpPost.getRequestLine());
  30.             // Create a custom response handler
  31.             ResponseHandler < String > responseHandler = response - > {
  32.                 int status = response.getStatusLine().getStatusCode();
  33.                 if (status >= 200 && status < 300) {
  34.                     HttpEntity entity = response.getEntity();
  35.                     return entity != null ? EntityUtils.toString(entity) : null;
  36.                 } else {
  37.                     throw new ClientProtocolException("Unexpected response status: " + status);
  38.                 }
  39.             };
  40.             String responseBody = httpclient.execute(httpPost, responseHandler);
  41.             System.out.println("----------------------------------------");
  42.             System.out.println(responseBody);
  43.         }
  44.     }
  45. }

输出

  1. Executing request POST http://httpbin.org/post HTTP/1.1
  2. ----------------------------------------
  3. {
  4.   "args": {}, 
  5.   "data": "Hello, World", 
  6.   "files": {}, 
  7.   "form": {}, 
  8.   "headers": {
  9.     "Accept-Encoding": "gzip,deflate", 
  10.     "Connection": "close", 
  11.     "Content-Length": "12", 
  12.     "Content-Type": "text/plain; charset=ISO-8859-1", 
  13.     "Host": "httpbin.org", 
  14.     "User-Agent": "Apache-HttpClient/4.5 (Java/1.8.0_172)"
  15.   }, 
  16.   "json": null, 
  17.   "origin": "49.35.12.218", 
  18.   "url": "http://httpbin.org/post"
  19. }

版权说明 : 本文为转载文章, 版权归原作者所有 版权申明

原文链接 : https://www.javaguides.net/2018/10/apache-httpclient-post-http-request-example.html

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