get与post两种方式的区别：对于本次主题而言，最显著的区别就是get请求方式参数是在url后，而post请求方式的参数是在request body中。因此两者获取参数的方式也大不一样。

@Getter
@Setter
@AllArgsConstructor
@NoArgsConstructor
public class User implements Serializable {
    private static final long serialVersionUID = 1L;
    @JsonProperty(value = "id")
    private Integer id;
    @JsonProperty(value = "name")
    private String name;
    @JsonProperty(value = "age")
    private Integer age;
    @JsonProperty(value = "hobby")
    private List<String> hobby;
}

Get方式参数的获取

-

直接在方法体中指定参数

@GetMapping("/get")
    public User getUserById(Integer id) {
        if (id.intValue() == 0) {
            return null;
        }
        return list.get(id);
    }

访问 http://ip:port/xx/get?id=1

使用requestParam

@GetMapping("/get")
    public User getUserById(@RequestParam(name = "id", required = true) Integer id) {
        if (id.intValue() == 0) {
            return null;
        }
        return list.get(id);
    }

其中RequestParam中name表示url中请求的字段名，当required为true时，表示该参数必填；defaultValue表示当该参数没有传递数据时给出的默认值，如defaultvalue=”0”

访问方式同上

使用PathVariable

@GetMapping("/get/{id}")
    public User getUserByPathValue(@PathVariable(name = "id", required = true) Integer id) {
        return list.get(id);
    }

该方式用来获取路径中的参数。@PathVariable中的字段含义同RequestParam
访问http:///ip:port/xx/get/1 ——->对应于get/{id}

使用HttpServletRequest

@GetMapping("/get")
    public User getUserById(HttpServletRequest request) {
        Integer id = Integer.parseInt(request.getParameter("id"));
        if (id.intValue() == 0) {
            return null;
        }
        return list.get(id);
    }

访问 http://ip:port/xx/get?id=1

POST方式参数的获取

一般而言，post形式的参数被放在请求体中以application/json的形式被后端获取

获取一个对象

content-type:application/json

    @PostMapping("/save")
    public User saveUser(@RequestBody User user) {
        list.add(user);
        return user;
    }

会把这些字段组装到对象中

使用Map

map中存放的键值对就对应于json中的键值对 content-type:application/json

   @PostMapping("/save")
     public User saveUser(@RequestBody Map<String, Object> map) {
     Integer id = (Integer) map.get("id");
     String name = (String) map.get("name");
     Integer age = (Integer) map.get("age");
     List<String> hobby=(List<String>) map.get("hobby");
     User user = new User(id, name, age, hobby);
     list.add(user);
     return user;
     }

使用HttpServletRequest

将content-type改为x-www-form-urlencoded

 @PostMapping("/save")
     public User save(HttpServletRequest request) {
     Integer id = Integer.parseInt(request.getParameter("id"));
     String name = request.getParameter("name");
     Integer age = Integer.parseInt(request.getParameter("age"));
     String parameter = request.getParameter("hobby");
     User user = new User(id, name, age, null);
     list.add(user);
     return user;
     }

• -

通过HTTP协议将参数转换为JSONObject

content-type:application/json

@PostMapping("/save")
    public User save(HttpServletRequest request) throws IOException, JSONException {

        JSONObject jsonObject = handlerData(request);
        Integer id = jsonObject.getInteger("id");
        String name = jsonObject.getString("name");
        Integer age = jsonObject.getInteger("age");
        List<String> hobby = jsonObject.getObject("hobby", List.class);
        User user = new User(id, name, age, hobby);
        list.add(user);
        return user;
    }
    //这里使用的是alibaba的json工具类
    public static JSONObject handlerData(HttpServletRequest request) throws IOException, JSONException {
        StringBuffer sb = new StringBuffer();
        InputStream is = request.getInputStream();
        BufferedReader br = new BufferedReader(new InputStreamReader(is, "utf-8"));
        String s = "";
        while ((s = br.readLine()) != null) {
            sb.append(s);
        }
        if (sb.toString().length() <= 0) {
            return null;
        } else {
            return JSONObject.parseObject(sb.toString());
        }
    }

本来使用的是org.json包下的JSONObject，无奈启动就报 org.json.JSONException，后改为使用alibaba的fastjson

注意：使用缓冲输入流读取的是这里的json，因此是一行一行读取的：

!
读取的时候 报出异常：not close json text,token:: 将json改为如下所示