spring boot——请求与参数校验——使用ResponseEntity处理http响应

package org.example.controller.requestparam;

import org.apache.ibatis.jdbc.Null;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class ResponseEntityController
{
    // http://localhost:8080//responseEntity
    /**
     * 通过 ResponseEntity 处理响应   基础使用
     * @param
     * @return
     */
    @RequestMapping("/responseEntity")
    public ResponseEntity<String> greeting(){

        return new ResponseEntity<>("hello there", HttpStatus.OK);
    }

    // http://localhost:8080//responseEntity-header
    /**
     * 通过 ResponseEntity 处理响应   添加自定义的http-header
     * @param
     * @return
     */
    @RequestMapping("/responseEntity-header")
    public ResponseEntity<String> greetingHeader(){

        HttpHeaders hds = new HttpHeaders();
        hds.add("Custem-Header","custemHeader");

        return new ResponseEntity<>("hello there", hds,HttpStatus.OK);
    }
    // httpStatus也可以返回不同的状态码


    @RequestMapping("/responseEntity-null")
    public ResponseEntity<Long> greetingNull(){


        return new ResponseEntity<>(null,HttpStatus.BAD_GATEWAY);
    }
}