Httpclient基础！！！！实战训练！！！！

标签：实战 http 请求训练 org apache import response Httpclient

1. HttpClient

1.1 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

为什么要在Java程序中发送Http请求？有哪些应用场景呢？

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

其实，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>

HttpClient的核心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

1.2 入门案例

如果想测试一下可以查看创建springboot项目

Springboot项目创建！！！接口测试！！！（零基础也能完成！！！直接速通！！！统一返回结果！！！Swagger集成Knife4j！！微信支付测试！！）前端Vue！！！（快速创建项目）_用浏览器测试springboot项目的接口-CSDN博客

对HttpClient编程工具包有了一定了解后，那么，我们使用HttpClient在Java程序当中来构造Http的请求，并且把请求发送出去，接下来，就通过入门案例分别发送GET请求和POST请求，具体来学习一下它的使用方法。

1.2.1 GET方式请求

正常来说，首先，应该导入HttpClient相关的坐标，但在项目中，就算不导入，也可以使用相关的API。

因为在项目中已经引入了aliyun-sdk-oss坐标：

<dependency>
<groupId>com.aliyun.oss</groupId>
<artifactId>aliyun-sdk-oss</artifactId>
</dependency>

上述依赖的底层已经包含了HttpClient相关依赖。

故选择导入或者不导入均可。

编写测试代码，发送GET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

package com.example.demo1;

import com.alibaba.fastjson.JSONObject;
import com.example.demo1.utlis.HttpClientUtil;
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;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

@SpringBootTest
class Demo1ApplicationTests {
    /**
     * 一个关于HttpClient简单的测试案例
     * @throws IOException
     */

    @Test
    public void testPlaceOrder() throws IOException {

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

        //创建请求对象
        HttpGet httpGet = new HttpGet("http://localhost:8090/api/product/test");

        //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();

    }
   
}

运行结果

1.2.2 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

 @Test
    public void testPost() throws Exception { 
        CloseableHttpClient httpClient=HttpClients.createDefault();

        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());
        entity.setContentEncoding("utf-8");
        entity.setContentType("application/json");
        httpPost.setEntity(entity);

        CloseableHttpResponse response=httpClient.execute(httpPost);
        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);
        //为什么要转成字符串，虽然后端传入的是json字符串，但是在响应的时候数据是以流的形势，而且
        //这里HttpEntity entity1=response.getEntity();是对象，所以要转
        //关闭资源
        response.close();
        httpClient.close();
    }

结果如下

1.3封装

代码如下：

package com.example.demo1.utlis;

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;

public class HttpClientUtil {
    static final  int TIMEOUT_MSEC = 5 * 1000;
    /**
     * get 请求
     * @param url
     * @param paramMap
     * @return
     */

    public static String doGet(String url, Map<String,Object> paramMap){
        // 创建Httpclient对象
        CloseableHttpClient httpClient = HttpClients.createDefault();

        String result = "";
        CloseableHttpResponse response = null;

        try{
            //URIBuilder 用于构建请求的 URL。
            URIBuilder builder = new URIBuilder(url);
            if(paramMap != null){
                for (String key : paramMap.keySet()) {
                    builder.addParameter(key, (String) paramMap.get(key));
                }
            }
            URI uri = builder.build();

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

            //发送请求，接受响应结果
            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
     * application/x-www-form-urlencoded 格式的字符串
     * @param url
     * @param paramMap
     * @return
     * @throws IOException
     */
    public static String doPost(String url, Map<String, Object> 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, Object> param : paramMap.entrySet()) {
                    paramList.add(new BasicNameValuePair(param.getKey(), (String) param.getValue()));
                }
                // 模拟表单
                //UrlEncodedFormEntity 专门用于将表单参数（键值对）转换为 application/x-www-form-urlencoded 格式的字符串
                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
     * Json格式
     * @param url
     * @param paramMap
     * @return
     * @throws IOException
     */
    public static String doPost4Json(String url, Map<String, Object> 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, Object> 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();
    }

}

然后可以简写

package com.example.demo1;

import com.alibaba.fastjson.JSONObject;
import com.example.demo1.utlis.HttpClientUtil;
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;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

@SpringBootTest
class Demo1ApplicationTests {
    /**
     * 一个关于HttpClient简单的测试案例
     * @throws IOException
     */

    @Test
    public void testPlaceOrder() throws IOException {

        String s = HttpClientUtil.doGet("http://localhost:8090/api/product/test", null);
        System.out.println(s);
       /* //创建httpclient对象
        CloseableHttpClient httpClient = HttpClients.createDefault();

        //创建请求对象
        HttpGet httpGet = new HttpGet("http://localhost:8090/api/product/test");

        //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();
*/
    }
    @Test
    public void testPost() throws Exception {
        Map map=new HashMap();
        map.put("username","admin");
        map.put("password","123456");

        String s = HttpClientUtil.doPost4Json("http://localhost:8080/admin/employee/login", map);
        System.out.println(s);
       /* CloseableHttpClient httpClient=HttpClients.createDefault();

        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());
        entity.setContentEncoding("utf-8");
        entity.setContentType("application/json");
        httpPost.setEntity(entity);

        CloseableHttpResponse response=httpClient.execute(httpPost);
        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);
        //为什么要转成字符串，虽然后端传入的是json字符串，但是在响应的时候数据是以流的形势，而且
        //这里HttpEntity entity1=response.getEntity();是对象，所以要转
        //关闭资源
        response.close();
        httpClient.close();*/
    }
}

同样能得到结果

标签：实战,http,请求,训练,org,apache,import,response,Httpclient
From： https://blog.csdn.net/qq_56947957/article/details/143863993