get请求

上代码干货，测试接口来源  http://www.httpbin.org/

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import org.apache.http.HttpEntity;
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;
import org.testng.annotations.Test;
import java.io.IOException;

public class HttpRequest {
    @Test
    public void httpGet() throws IOException {
        //创建client有两种途径，查看源码可知最终都是调用 HttpClientBuilder.create().build();
        CloseableHttpClient client= HttpClients.createDefault();
        //CloseableHttpClient client= HttpClients.custom().build();

        //创建 get 对象,
        HttpGet get=new HttpGet("http://www.httpbin.org/get");
        //设置 请求头
        get.setHeader("Referer","http://www.httpbin.org/");
        get.setHeader("accept","application/json");
        // HttpGet还可以设置connectTimeout,socketTimeout等，使用 get.setConfig();

        //获取响应
        CloseableHttpResponse response=client.execute(get);
        HttpEntity entity=response.getEntity();
        String result=EntityUtils.toString(entity);
        //关闭流,释放连接
        EntityUtils.consume(entity);
        response.close();

        //解析result，是json的话，可以使用 fastjson来解析
        JSONObject resultJson= JSON.parseObject(result);
        System.out.println(resultJson.getString("headers"));
    }
}

1. 设置请求头有两个方法：

　　httpGet.setHeader("key","value");  设置一个请求头，有则覆盖，无则新增

　　httpGet.addHeader("key","value");  添加一个新的请求头，允许有重复

2. 请求头常见的三种 content-type 

　　application/x-www-form-urlencoded ，会将表单参数携带在url中进行传递，可以直接将参数用键=值&键=值的形式进行拼接到url中

　　application/json， 将参数以json格式进行传递

　　multiPart/form-data，混合表单，上传文件时使用

3. 关于  get.setConfig() ，其中的更多属性设置查看源码可知

结果

{"Accept":"application/json","Referer":"http://www.httpbin.org/","User-Agent":"Apache-HttpClient/4.5.3 (Java/1.8.0_231)","Host":"www.httpbin.org","Accept-Encoding":"gzip,deflate"}