HTTP请求(HttpClient和PostMan)

在没有页面的情况下来获取接口返回的数据(一般都是为JSON),我们可以通过一些工具模拟HTTP请求

服务端模拟HTTP请求

通过JAVA代码进行HTTP请求的发送

1.准备依赖

    <!-- https://mvnrepository.com/artifact/org.apache.httpcomponents/httpclient -->
    <dependency>
      <groupId>org.apache.httpcomponents</groupId>
      <artifactId>httpclient</artifactId>
      <version>4.5.6</version>
    </dependency>

2.创建post和get方式请求的方法

package com.ty.http;


import org.apache.http.HttpEntity;
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.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.util.ArrayList;
import java.util.List;

public class MyHttpClient {
    private static void myPost() throws IOException {
        //建立连接请求
        CloseableHttpClient httpClient = HttpClients.createDefault();
        //创建post请求
        HttpPost httpPost = new HttpPost("http://eureka7002.com:6061/myServlet");
        //创建参数队列
        List<NameValuePair> nameValuePairList=new ArrayList<>();
        //准备请求参数队列
        nameValuePairList.add(new BasicNameValuePair("userName","天雁"));
        //
        UrlEncodedFormEntity urlEncodedFormEntity=new UrlEncodedFormEntity(nameValuePairList,"UTF-8");
        //讲实体封装到请求当中
        httpPost.setEntity(urlEncodedFormEntity);
        //发送请求
        CloseableHttpResponse response = httpClient.execute(httpPost);
        HttpEntity entity = response.getEntity();
        if (entity!=null){
            System.out.println("接收到的响应信息:--------"+EntityUtils.toString(entity,"UTF-8"));
        }
        //资源释放
        response.close();
        httpClient.close();

    }

    private static void myGet() throws IOException {

        //建立连接请求
        CloseableHttpClient httpClient = HttpClients.createDefault();
        //创建get请求
        HttpGet get=new HttpGet("https://www.baidu.com/");
        CloseableHttpResponse response = httpClient.execute(get);
        int statusCode = response.getStatusLine().getStatusCode();
        //响应成功在操作
        if (statusCode==200) {
            //获取响应实体
            HttpEntity entity = response.getEntity();

            //打印响应内容长度
            System.out.println("响应文本长度:"+entity.getContentLength());
            //打印响应内容
            System.out.println("响应内容如下:\n"+EntityUtils.toString(entity,"UTF-8"));
        }
        System.out.println("--------------------------响应内容打印完毕");
        //释放资源
        response.close();
        httpClient.close();
    }

    public static void main(String[] args) {
        try {
          //  myGet();
            myPost();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

4.get测试百度返回结果

5.post测试本机的另一个服务

5.1给项目准备依赖

    <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>com.alibaba</groupId>
      <artifactId>fastjson</artifactId>
      <version>1.2.58</version>
    </dependency>

5.2创建一个Servlet,接收一个参数,返回json串

package com.ty.servlet;

import com.alibaba.fastjson.JSON;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet("/myServlet")
public class MyServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    doPost(req,resp);
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("UTF-8");
        String userName = req.getParameter("userName");
        resp.setHeader("Content-type", "text/html;charset=UTF-8");
        System.out.println("接受到的数据:"+userName);
        String json="成功响应";
        resp.getWriter().write(JSON.toJSONString(json));
    }
}