【Web后端】java发起HTTP请求

引入依赖

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.2</version>
</dependency>

导入jar包

import com.alibaba.fastjson.JSONObject;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
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.HttpClientBuilder;
import org.apache.http.message.BasicHeader;
import org.apache.http.protocol.HTTP;
import org.apache.http.util.EntityUtils;

发起HTTP请求

get方法

String url = "url";
//创建HttpClient对象
CloseableHttpClient httpClient = HttpClientBuilder.create().build();
HttpGet httpGet = new HttpGet(url);
try {
    HttpResponse response = httpClient.execute(httpGet);
    //HttpStatus.SC_OK = 200
    if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
        JSONObject obj = JSONObject.parseObject(res);
        System.out.println(obj);
    }
} catch (IOException e) {
    e.printStackTrace();
}

post方法

JSONObjcet result = new JSONObject();

// 创建HttpPost对象，设置URL地址
HttpPost httpPost=new HttpPost(URL);

// 封装参数
JSONObject param = new JSONObject();
param.put("name","tom");

//装填参数
StringEntity entity = new StringEntity(param.toString(), "utf-8");
entity .setContentEncoding(new BasicHeader(HTTP.CONTENT_TYPE,"application/json"));

//设置参数到请求对象中
httpPost.setEntity(entity);

//设置报头
httpPost.setHeader("Content-type", "application/json");

try{
    //执行请求操作，并拿到结果（同步阻塞）
    CloseableHttpResponse response = httpClient.execute(httpPost);
    //获取结果实体
    HttpEntity entity = response.getEntity();
    if (entity != null) {
        //按指定编码转换结果实体为String类型
        String res = EntityUtils.toString(entity, "UTF-8");
        result= JSONObject.parseObject(res);
    }
    //释放链接
    response.close();
}catch (IOException e) {
    e.printStackTrace();
}

return result;