RestTemplate、HttpHeaders、HttpEntity<String>

import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.web.client.RestTemplate;

public static String handelPost(String url, String body){
   RestTemplate restTemplate = new RestTemplate();
   HttpHeaders headers = new HttpHeaders();
   HttpEntity<String> formEntity = new HttpEntity<>(body, headers);
   String str= restTemplate.postForEntity(url, formEntity, String.class).getBody();
   return str;
}

HttpEntity和@RequestBody和@ResponseBody很像。除了能够访问请求和响应体，HttpEntity（和子类ResponseEntity）也能访问请求（和响应）头

@RequestMapping("/something")

public ResponseEntity<String> handle(HttpEntity<byte[]> requestEntity) throws UnsupportedEncodingException 

{
    String requestHeader = requestEntity.getHeaders().getFirst("MyRequestHeader");
    byte[] requestBody = requestEntity.getBody();
    // do something with request header and body
    HttpHeaders responseHeaders = new HttpHeaders();
    responseHeaders.set("MyResponseHeader", "MyValue");
    return new ResponseEntity<String>("Hello World", responseHeaders, HttpStatus.CREATED);
}

  上面的例子获取MyRequestHeader请求头的值，读取请求体为字节数组。还把MyResponseHeader添加到响应中，把Hello World写到响应流中，并设置响应状态码为 201（创建）。

  就像@RequestBody和@ResponseBody一样，Spring 使用HttpMessageConverter在请求和响应流之间进行转换。