HttpClientUtil

博客介绍了使用CloseableHttpClient的相关内容,这在后端开发的网络请求处理等方面有重要应用,能帮助开发者实现与外部服务的交互。

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使用CloseableHttpClient

package com.bjsxt.springboothelloworld;

import java.io.IOException;
import java.net.URI;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import org.apache.http.NameValuePair;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;

public class HttpClientUtil {

	public static String doGet(String url, Map<String, String> param) {

		// 创建Httpclient对象
		CloseableHttpClient httpclient = HttpClients.createDefault();

		String resultString = "";
		CloseableHttpResponse response = null;
		try {
			// 创建uri
			URIBuilder builder = new URIBuilder(url);
			if (param != null) {
				for (String key : param.keySet()) {
					builder.addParameter(key, param.get(key));
				}
			}
			URI uri = builder.build();

			// 创建http GET请求
			HttpGet httpGet = new HttpGet(uri);

			// 执行请求
			response = httpclient.execute(httpGet);
			// 判断返回状态是否为200
			if (response.getStatusLine().getStatusCode() == 200) {
				resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				if (response != null) {
					response.close();
				}
				httpclient.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return resultString;
	}

	public static String doGet(String url) {
		return doGet(url, null);
	}

	public static String doPost(String url, Map<String, String> param) {
		// 创建Httpclient对象
		CloseableHttpClient httpClient = HttpClients.createDefault();
		CloseableHttpResponse response = null;
		String resultString = "";
		try {
			// 创建Http Post请求
			HttpPost httpPost = new HttpPost(url);
			// 创建参数列表
			if (param != null) {
				List<NameValuePair> paramList = new ArrayList<>();
				for (String key : param.keySet()) {
					paramList.add(new BasicNameValuePair(key, param.get(key)));
				}
				// 模拟表单
				UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList,"utf-8");
				httpPost.setEntity(entity);
			}
			// 执行http请求
			response = httpClient.execute(httpPost);
			resultString = EntityUtils.toString(response.getEntity(), "utf-8");
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				response.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}

		return resultString;
	}

	public static String doPost(String url) {
		return doPost(url, null);
	}
	
	public static String doPostJson(String url, String json) {
		// 创建Httpclient对象
		CloseableHttpClient httpClient = HttpClients.createDefault();
		CloseableHttpResponse response = null;
		String resultString = "";
		try {
			// 创建Http Post请求
			HttpPost httpPost = new HttpPost(url);
			// 创建请求内容
			StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);
			httpPost.setEntity(entity);
			// 执行http请求
			response = httpClient.execute(httpPost);
			resultString = EntityUtils.toString(response.getEntity(), "utf-8");
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				response.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}

		return resultString;
	}
	
	public static void main(String[] args) {
		String url ="http://127.0.0.1:9090/shutdown";
		//该url必须要使用dopost方式来发送
		HttpClientUtil.doPost(url);
	}
}

 

### HttpClientUtil 类使用示例 #### 工具类概述 `HttpClientUtils` 是一个封装了常用 HTTP 请求操作的工具类,基于 Apache HttpClient 实现。该工具类支持 GET、POST、PUT、DELETE 等常见的请求方法,并提供了请求头设置、参数传递、响应处理以及超时设置等功能[^1]。 #### Maven依赖配置 为了使用 `HttpClientUtils` 或者直接使用 Apache HttpClient 进行开发,项目中需要引入相应的 Maven 依赖: ```xml <dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> <version>4.5.13</version> </dependency> <dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpmime</artifactId> <version>4.5.13</version> </dependency> ``` #### 发送GET请求实例 下面是一个简单的发送 GET 请求并打印服务器返回内容的例子: ```java import org.apache.http.client.methods.CloseableHttpResponse; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import org.apache.http.util.EntityUtils; public class HttpClientExample { public static void main(String[] args) throws Exception { CloseableHttpClient httpClient = HttpClients.createDefault(); try { HttpGet request = new HttpGet("https://jsonplaceholder.typicode.com/posts/1"); // 执行GET请求 CloseableHttpResponse response = httpClient.execute(request); try { System.out.println(EntityUtils.toString(response.getEntity())); } finally { response.close(); } } finally { httpClient.close(); } } } ``` 此代码创建了一个默认的 `CloseableHttpClient` 对象来执行 HTTP 请求。通过构建 `HttpGet` 来指定目标 URL 并调用 `execute()` 方法发起请求。最后读取响应实体的内容并通过 `EntityUtils.toString()` 转换成字符串形式输出到控制台[^4]。 对于更复杂的场景,比如 POST 表单提交或者上传文件,则可以通过调整上述模板中的具体实现细节完成相应功能需求。
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