Unity向Node.js服务器发送JSON时字符长度异常问题

从服务器输出的字符串能明显看到，Unity发送的username和password末尾带有不可见的空白/零宽字符，这就是导致字符串长度多1的核心原因。大概率是Unity UI输入框（loginEmail、loginPassword）的文本中混入了用户输入时误加的换行、空格，或是输入框组件本身的格式残留问题。

最直接的解决方式是从客户端源头清理无效字符，在Unity端对输入文本做首尾空白去除处理，同时添加调试日志确认处理结果。如果需要也可在服务器端添加兜底逻辑。

修改后的Unity代码（SendData.cs） #

public void SendLogin()
{
    StartCoroutine(Login());
}

private IEnumerator Login()
{
    // 清理输入文本首尾的空白、换行等不可见字符
    var email = loginEmail.text.Trim();
    var password = loginPassword.text.Trim();
    var loginData = new LoginData();
    loginData.username = email;
    loginData.password = password;
    var json = JsonUtility.ToJson(loginData);

    // 调试用：打印处理后的内容和长度，确认是否正常
    Debug.Log($"序列化后的JSON: {json}");
    Debug.Log($"清理后username长度: {email.Length}");

    using UnityWebRequest webRequest = new UnityWebRequest(loginUrl, "POST");
    webRequest.SetRequestHeader("Content-Type", "application/json; charset=utf-8");
    byte[] rawJson = System.Text.Encoding.UTF8.GetBytes(json);
    webRequest.uploadHandler = new UploadHandlerRaw(rawJson);
    webRequest.downloadHandler = new DownloadHandlerBuffer();
    yield return webRequest.SendWebRequest();

    switch(webRequest.result)
    {
        case UnityWebRequest.Result.InProgress:
            Debug.Log("In Progress...");
            break;
        case UnityWebRequest.Result.Success:
            Debug.Log(webRequest.downloadHandler.text);
            break;
        case UnityWebRequest.Result.ConnectionError:
            Debug.Log("Connection Error...");
            break;
        case UnityWebRequest.Result.ProtocolError:
            Debug.Log("Protocol Error...");
            break;
        case UnityWebRequest.Result.DataProcessingError:
            Debug.Log("Data Processing Error...");
            break;
        default:
            Debug.Log("Default...");
            break;
    }
}

服务器端兜底方案（可选） #

如果客户端处理后仍有异常，可在服务器路由中添加字符清理逻辑：

router.post('/login', async (req, res, next) => {
    // 服务器端兜底清理首尾空白
    let username = req.body.username.trim();
    let password = req.body.password.trim();
    console.log('req.body = ' + JSON.stringify({username, password}));
    console.log('req.body.username.length = ' + username.length);
    
    User.findOne({email: username})
    .then(async(user) => {
        if(!user) {
            console.log('not found');
            return res.status(401).send('Invalid Credentials.')
        }

        if (user.failedLoginAttempts >= allowedFailedLoginAttempts) {
            return res.status(401).send('Account Locked.')
        }

        const isValidPassword = await GSUtility.isValidPassword(password, user.password)

        if (isValidPassword) {
            console.log('good');
            const jwt = GSUtility.issueJWT(user);
            user.updateLogin();
            return res.status(200).send({ user: user, token: jwt.token, expires: jwt.expires })
        } else {
            user.increaseFailedLoginAttempts();
            console.log('bad info');
            return res.status(401).send('Invalid Credentials.')
        }
    })
});

内容的提问来源于stack exchange，提问作者K.G