java http请求必需的字符串参数'用户名'不存在

Question

我正在运行一个接受 http 请求的 Spring Boot 服务器。 我已经用 curl 对其进行了广泛的测试，并且效果很好。 但是，当我尝试在 java 客户端中发送请求并接收响应时，我得到：

java.io.IOException：服务器返回 HTTP 响应代码：URL 为 400：

在服务器端我得到：

[org.springframework.web.bind.MissingServletRequestParameterException：必需的字符串参数'用户名'不存在]

这是我尝试使用的spring boot方法：

@PostMapping(path="/CreateAccount") // Map ONLY POST Requests
  public @ResponseBody String CreateUser (@RequestParam String Username
                                        , @RequestParam String Password) {
    // @ResponseBody means the returned String is the response, not a view name
    // @RequestParam means it is a parameter from the GET or POST request
    //make sure the username and password is valid input
      if (!validateInput(Username) || !validateInput(Password))
      {
          return "Username and Password cannot be blank";
      }
    //make sure the username is unique
      //check if Username is equal to any other User's username
      User u = findByUsername(Username);
      //if a user was found in the table
      if ( !(u == null) )
      {
          return "Username already taken\nPlease choose another";
      }

      //if we are here we are clear to make a new user
    User n = new User();
    n.setUsername(Username);
    n.setPassword(Password);
    n.setRole("Player");
    userRepository.save(n);

    //THIS CAUSES AN ERROR
    //create a stat object to be added to the table
    Stats s = new Stats();
    s.setUsername(Username);
    statRepository.save(s);

    //create a token for the user
    String usrToken = createToken(tokenSize);
    //add the username and token to hashmap
    userTokens.put(Username, usrToken);

    //return this user's token
    return usrToken;
  }

这是我的客户：

public static void CreateAccount(String username, String password) 
    {
        try
        {
            String s = serverURL + "/CreateAccount";
            URL url = new URL(s);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();

            connection.setRequestMethod("POST"); 
            connection.setRequestProperty("Accept", "application/json");
            connection.setRequestProperty("Content-Type", "application/json; utf-8");
            connection.setDoOutput(true);

            String json = "[{\n\"Username\"=\"Jake\",\"Password\"=\"123\"\n}]";
            System.out.println(json);

            OutputStream os = connection.getOutputStream();
            DataOutputStream out = new DataOutputStream( os );
            byte[] input = json.getBytes("utf-8");

            out.writeUTF(json); 

            BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            String response = br.readLine();
            System.out.println(response);


        } 
        catch (Exception e)
        {
            System.out.println("#");
            System.out.println(e);
        }
    }

我认为这与我的 json 格式有关，但我反复尝试，无论我如何格式化，我都会遇到同样的错误。

Answer 1

如果要发送 json 对象，请使用以下代码：

@PostMapping(path="/CreateAccount")
public @ResponseBody String CreateUser (@RequestBody User user) {

    if (user == null)
    {
        return "User cannot be blank";
    }

    User u = findByUsername(user.Username);

    // your code...

    return usrToken;
}