HttpClientr入门

HttpClientr入门

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协议的版本和建议。

依赖导入

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

核心API

• HttpClient
• HttpClients
• CloseableHttpClient
• HttpGet
• HttpPost

发送请求步骤：

1. 创建HttpClient对象
2. 创建Http请求对象
3. 调用HttpClient的execute方法发送请求

import com.alibaba.fastjson.JSONObject;
import lombok.extern.slf4j.Slf4j;
import org.apache.http.HttpEntity;
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.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
@Slf4j
public class HttpClientTest {

    @Test
    public void HttpGET() throws Exception {
        //1.创建请求HttpClient对象
        CloseableHttpClient httpClient = HttpClients.createDefault();

        //2.创建Http请求对象
        HttpGet httpGet = new HttpGet("http://localhost:8080/user/shop/status");

        //3.调用HttpClient的execute方法发送请求
        CloseableHttpResponse response = httpClient.execute(httpGet);

        //获取数据
        //获取响应的状态码
        int code = response.getStatusLine().getStatusCode();
        System.out.println("返回的状态码是:"+code);
        //获取响应的数据
        HttpEntity entity = response.getEntity();
        String body = EntityUtils.toString(entity);
        System.out.println("服务器返回的数据为："+body);

        //关闭请求
        httpClient.close();
        response.close();
    }
    @Test
    public void HttpPost() throws Exception{

        //创建HttpClient对象
        CloseableHttpClient httpClient = HttpClients.createDefault();

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

        //构建请求的参数
        JSONObject jsonObject = new JSONObject();
        jsonObject.put("username","admin");
        jsonObject.put("password","123456");
        StringEntity stringEntity = new StringEntity(jsonObject.toString());
        //指定编码格式
        stringEntity.setContentEncoding("utf-8");
        //数据格式
        stringEntity.setContentType("application/json");
        post.setEntity(stringEntity);
        //发送请求
        CloseableHttpResponse response = httpClient.execute(post);

        //获取响应回来的参数
        int statusCode = response.getStatusLine().getStatusCode();
        System.out.println("状态码："+statusCode);
        HttpEntity entity = response.getEntity();
        String body = EntityUtils.toString(entity);
        System.out.println("post请求响应回来的参数："+body);

        //关闭服务
        httpClient.close();
        post.clone();
    }
}

HttpClientUtil 工具类，使用的时候直接调用

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();
    }

}