Springboot中@PathVariable，@RequestParam，@RequestBody，HttpServletRequest区别

@PathVariable

//接收请求URL中占位符的值
@GetMapping("/getId/{id}")//{id}写在请求URL中，参数来源于URL中，所以@PathVariable可以多个
//单个入参时id可不写，多个入参需要写
public String pathVariable(@PathVariable("id") Integer id) {

}

@RequestParam

//将URL的请求参数绑定到控制器的方法参数上
@GetMapping("/getId")//例：getId?id=0001，参数来源于URL中，所以@RequestParam可以多个
//单个入参时id可不写，甚至@RequestParam("id")都可不写，多个入参需要写全
public String requestParam(@RequestParam("id") Integer id) {

}

@RequestBody

//接收的是请求体里面的数据
@PostMapping("/getRequestBody")
//入参可以为：实体类，Map ，JsonObject，String等可存储key-value的对象
//参数来源于请求body中，所以@RequestBody只能一个
public String RequestBody(@RequestBody User user) {

}

HttpServletRequest

//通过getParameter直接获取，参数来源于URL中
@GetMapping("/getHttpServletRequest")
public String getHttpServletRequestValue(HttpServletRequest request) {
  String id = request.getParameter("id");
}

//通过参数集获取，参数来源于URL中
@GetMapping("/getHttpServletRequest")
public String getHttpServletRequestValue(HttpServletRequest request) {
  Map<String, String[]> parameterMap = request.getParameterMap();
  String[] ids = parameterMap.get("id");
  String id = ids[0];
}

//通过流获取body中的值，参数来源于请求body中
@PostMapping("/getHttpServletRequest")
public String getHttpServletRequestValue(HttpServletRequest request) throws IOException {
  BufferedReader reader = new BufferedReader(new InputStreamReader(request.getInputStream()));
  String line = "";
  String body = "";
  while((line = reader.readLine()) != null){
    body += line;
  }
  JSONObject jsonObject=JSONObject.parseObject(body);
  Integer id =  jsonObject.getInteger("id");
}