我在Postman中成功请求Token，但在React Native项目中：
{“error”：“unsupported_grant_type”}
我的代码是从PostMan复制的：

var myHeaders = new Headers();
    myHeaders.append("Content-Type", "application/x-www-form-urlencoded");

    var urlencoded = new URLSearchParams();
    urlencoded.append("username", "hoanglongit96");
    urlencoded.append("password", "admin");
    urlencoded.append("grant_type", "password");

    var requestOptions = {
        method: 'POST',
        headers: myHeaders,
        body: urlencoded,
        redirect: 'follow'
    };

    fetch("http://192.168.1.38:7777/token", requestOptions)
        .then(response => response.text())
        .then(result => console.log(result))
        .catch(error => console.log('error', error));

字符串
测试结果：
{“error”：“unsupported_grant_type”}
我试着添加接受：application/json在header中