HttpClient常用操作及封装工具类

介绍

HttpClient 是Apache Jakarta Common 下的子项目，可以用来提供高效的、最新的、功能丰富的支持 HTTP 协议的客户端编程工具包，并且它支持 HTTP 协议最新的版本和建议。

HttpClient作用：

发送HTTP请求
接收响应数据

HttpClient应用场景：

当我们在使用扫描支付、查看地图、获取验证码、查看天气等功能时

应用程序本身并未实现这些功能，都是在应用程序里访问提供这些功能的服务，访问这些服务需要发送HTTP请求，并且接收响应数据，可通过HttpClient来实现。

HttpClient的maven坐标：

<dependency>
	<groupId>org.apache.httpcomponents</groupId>
	<artifactId>httpclient</artifactId>
	<version>4.5.13</version>
</dependency>

核心API

HttpClient：Http客户端对象类型，使用该类型对象可发起Http请求。
HttpClients：可认为是构建器，可创建HttpClient对象。
CloseableHttpClient：实现类，实现了HttpClient接口。
HttpGet：Get方式请求类型。
HttpPost：Post方式请求类型。

HttpClient发送请求步骤：

创建HttpClient对象
创建Http请求对象
调用HttpClient的execute方法发送请求

案例

GET方式请求

实现步骤：

创建HttpClient对象
创建请求对象
发送请求，接受响应结果
解析结果
关闭资源

@SpringBootTest
public class HttpClientTest {
    
    
    /**
     * 测试通过httpclient发送GET方式的请求
     */
    @Test
    public void testGET() throws Exception{
    
    
        //创建httpclient对象
        CloseableHttpClient httpClient = HttpClients.createDefault();

        //创建请求对象
        HttpGet httpGet = new HttpGet("http://localhost:8080/user/shop/status");

        //发送请求，接受响应结果
        CloseableHttpResponse response = httpClient.execute(httpGet);

        //获取服务端返回的状态码
        int statusCode = response.getStatusLine().getStatusCode();
        System.out.println("服务端返回的状态码为：" + statusCode);

        HttpEntity entity = response.getEntity();
        String body = EntityUtils.toString(entity);
        System.out.println("服务端返回的数据为：" + body);

        //关闭资源
        response.close();
        httpClient.close();
    }
}

POST方式请求

在HttpClientTest中添加POST方式请求方法，相比GET请求来说，POST请求若携带参数需要封装请求体对象，并将该对象设置在请求对象中。

实现步骤：

创建HttpClient对象
创建请求对象
发送请求，接收响应结果
解析响应结果
关闭资源

/**
* 测试通过httpclient发送POST方式的请求
*/
@Test
public void testPOST() throws Exception{
    
    
// 创建httpclient对象
CloseableHttpClient httpClient = HttpClients.createDefault();

//创建请求对象
HttpPost httpPost = new HttpPost("http://localhost:8080/admin/employee/login");

JSONObject jsonObject = new JSONObject();
jsonObject.put("username","admin");
jsonObject.put("password","123456");

StringEntity entity = new StringEntity(jsonObject.toString());
//指定请求编码方式
entity.setContentEncoding("utf-8");
//数据格式
entity.setContentType("application/json");
httpPost.setEntity(entity);

//发送请求
CloseableHttpResponse response = httpClient.execute(httpPost);

//解析返回结果
int statusCode = response.getStatusLine().getStatusCode();
System.out.println("响应码为：" + statusCode);

HttpEntity entity1 = response.getEntity();
String body = EntityUtils.toString(entity1);
System.out.println("响应数据为：" + body);

//关闭资源
response.close();
httpClient.close();
}

工具类

import com.alibaba.fastjson.JSONObject;
import org.apache.http.NameValuePair;
import org.apache.http.client.config.RequestConfig;
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.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;

import java.io.IOException;
import java.net.URI;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
/**
 * Http工具类
 */
public class HttpClientUtil {
    
    

    static final int TIMEOUT_MSEC = 5 * 1000;

    /**
     * 发送GET方式请求
     *
     * @param url
     * @param paramMap
     * @return
     */
    public static String doGet(String url, Map<String, String> paramMap) {
    
    
        // 创建Httpclient对象
        CloseableHttpClient httpClient = HttpClients.createDefault();

        String result = "";
        CloseableHttpResponse response = null;

        try {
    
    
            URIBuilder builder = new URIBuilder(url);
            if (paramMap != null) {
    
    
                for (String key : paramMap.keySet()) {
    
    
                    builder.addParameter(key, paramMap.get(key));
                }
            }
            URI uri = builder.build();

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

            //发送请求
            response = httpClient.execute(httpGet);

            //判断响应状态
            if (response.getStatusLine().getStatusCode() == 200) {
    
    
                result = EntityUtils.toString(response.getEntity(), "UTF-8");
            }
        } catch (Exception e) {
    
    
            e.printStackTrace();
        } finally {
    
    
            try {
    
    
                response.close();
                httpClient.close();
            } catch (IOException e) {
    
    
                e.printStackTrace();
            }
        }

        return result;
    }

    /**
     * 发送POST方式请求
     *
     * @param url
     * @param paramMap
     * @return
     * @throws IOException
     */
    public static String doPost(String url, Map<String, String> paramMap) throws IOException {
    
    
        // 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 (paramMap != null) {
    
    
                List<NameValuePair> paramList = new ArrayList();
                for (Map.Entry<String, String> param : paramMap.entrySet()) {
    
    
                    paramList.add(new BasicNameValuePair(param.getKey(), param.getValue()));
                }
                // 模拟表单
                UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList);
                httpPost.setEntity(entity);
            }

            httpPost.setConfig(builderRequestConfig());

            // 执行http请求
            response = httpClient.execute(httpPost);

            resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
        } catch (Exception e) {
    
    
            throw e;
        } finally {
    
    
            try {
    
    
                response.close();
            } catch (IOException e) {
    
    
                e.printStackTrace();
            }
        }

        return resultString;
    }

    /**
     * 发送POST方式请求
     *
     * @param url
     * @param paramMap
     * @return
     * @throws IOException
     */
    public static String doPost4Json(String url, Map<String, String> paramMap) throws IOException {
    
    
        // 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);

            if (paramMap != null) {
    
    
                //构造json格式数据
                JSONObject jsonObject = new JSONObject();
                for (Map.Entry<String, String> param : paramMap.entrySet()) {
    
    
                    jsonObject.put(param.getKey(), param.getValue());
                }
                StringEntity entity = new StringEntity(jsonObject.toString(), "utf-8");
                //设置请求编码
                entity.setContentEncoding("utf-8");
                //设置数据类型
                entity.setContentType("application/json");
                httpPost.setEntity(entity);
            }

            httpPost.setConfig(builderRequestConfig());

            // 执行http请求
            response = httpClient.execute(httpPost);

            resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
        } catch (Exception e) {
    
    
            throw e;
        } finally {
    
    
            try {
    
    
                response.close();
            } catch (IOException e) {
    
    
                e.printStackTrace();
            }
        }

        return resultString;
    }

    private static RequestConfig builderRequestConfig() {
    
    
        return RequestConfig.custom()
                .setConnectTimeout(TIMEOUT_MSEC)
                .setConnectionRequestTimeout(TIMEOUT_MSEC)
                .setSocketTimeout(TIMEOUT_MSEC).build();
    }

}

HttpClient常用操作及封装工具类

目录

介绍

核心API

案例

GET方式请求

POST方式请求

工具类

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