java操作http请求的三种方式

一、HttpClient

步骤：

1.获取一个Http客户端

CloseableHttpClient httpClient=HttpClients.createDefault();

2.创建一个请求

HttpGet httpGet = new HttpGet("http://sign.hrit.haier.net/api/get");//get请求
HttpPost httpPost = new HttpPost("http://sign.hrit.haier.net/api/get"); //post请求
HttpPut httpPut = new HttpPut("http://sign.hrit.haier.net/api/get");  //put请求
HttpDelete httpDelete = new HttpDelete("http://sign.hrit.haier.net/api/get"); //delete请求
......

3.设置请求头（不需要可忽略）

//设置请求头请求体的格式为JSON
httpPost.setHeader("Content-Type","application/json;charset=UTF-8");
//在请求头设置认证token
httpPost.setHeader("Authorization","Basic " + Base64.getEncoder().encodeToString("username:password".getBytes()));

4.设置请求参数

//设置请求参数
HttpEntity httpEntity = new StringEntity(JSON.toJSONString(null), ContentType.APPLICATION_JSON);
//将参数放入请求
httpPost.setEntity(httpEntity);

5.执行请求并获取响应

CloseableHttpResponse response = httpClient.execute(httpPost);
System.out.println(EntityUtils.toString(response.getEntity()));

6.关闭连接

response.close();
httpClient.close();

例如

 public void testGetWithRest(){
        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpGet httpGet = new HttpGet("http://sign.hrit.haier.net/api/get");
        HttpPost httpPost = new HttpPost("http://sign.hrit.haier.net/api/get");
        HttpPut httpPut = new HttpPut("http://sign.hrit.haier.net/api/get");
        HttpDelete httpDelete = new HttpDelete("http://sign.hrit.haier.net/api/get");
        httpPost.setHeader("Content-Type","application/json;charset=UTF-8");
        httpPost.setHeader("Authorization","Basic " + Base64.getEncoder().encodeToString("username:password".getBytes()));
        CloseableHttpResponse response =null;
        try {
            HttpEntity httpEntity = new StringEntity(JSON.toJSONString(null), ContentType.APPLICATION_JSON);
            httpPost.setEntity(httpEntity);
            long time = System.currentTimeMillis();
            response = httpClient.execute(httpPost);
            System.out.println("延迟时间：" + (System.currentTimeMillis() - time));
            System.out.println(response.getStatusLine().getStatusCode());
            System.out.println(EntityUtils.toString(response.getEntity()));
            response.close();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if (response !=null){
                try {
                    response.close();
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            if (httpClient!=null){
                try {
                    httpClient.close();
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
        }
    }

二、RestTemplate

步骤：

1.获取一个Http客户端或注入一个RestTemplate

RestTemplate template = new RestTemplate();

2.创建一个请求头，并设置参数

//创建一个请求头
HttpHeaders headers = new HttpHeaders();
//设置请求头的参数类型为JSON
headers.setContentType(MediaType.APPLICATION_JSON);
//设置请求头的权限认证参数
headers.setBasicAuth("");

3.使用参数和请求头创建一个HttpEntity

 HttpEntity<Object> http = new HttpEntity<>(new MdmCustomer(),headers);

4.发送请求并获取返回值

ResponseEntity<String> http1 = template.postForEntity("http://localhost:8080/dept", http, String.class);
System.out.println(http1.getStatusCode().value());
System.out.println(http1.getBody());

三、OpenFeign

@FeignClient(name = "cv" ,url = "http://localhost:8080/dept")
public interface CustomerVendorRemote {
    @PostMapping(value = "/aa",produces = MediaType.APPLICATION_JSON_VALUE,headers="Authorization=Basic ${third.erp.authorization}")
    String queryDataOnTime(@RequestBody Dept dept);
}

url:指定的http的url地址
headers：设置请求的请求头信息
produces:设置响应类型为JSON
@ReuestBody：设置请求参数为JSON