java为什么JWT令牌不安全？

Question

我正在我的spring boot项目中使用JWT令牌。我很惊讶我的JWT令牌从他们的官方网站上被解码，所有数据都从令牌中恢复。 这是我的代币 eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJTdGVlbERvYyIsImV4cCI6MTU1NzU2ODQ1MiwibG9naW5JZCI6ImFkbWluIiwidXNlcklkIjoyLCJlbWFpbElkIjoiZGhpcmVuZHJhQHRlc3QuY29tIn0.o4UKtwO22cAXLjIsUuDRgAQf7OjUbe_O9DbSGxPYgfQ

解码的链接link..

这是我的密码

public class JwtHelper {

static String subject = "SteelDoc";
static String secret = "faa76006-6fef-413d-9cae-a05e63170cbf";

Integer userId = null;
String loginId = "";
String emailId = "";

public String getUserName() {
    return loginId;
}

public void setUserName(String userName) {
    this.loginId = userName;
}

public Integer getUserId() {
    return userId;
}

public void setUserId(Integer userId) {
    this.userId = userId;
}

public String getToken(String loginId, Integer userId, String email) {
    try {
        Date d = new Date();
        Date de = d;
        de.setYear(de.getYear() + 1);
        String jwt = Jwts.builder().setSubject(subject).setExpiration(de).claim("loginId", loginId)
                .claim("userId", userId).claim("emailId", email)
                .signWith(SignatureAlgorithm.HS256, secret.getBytes("UTF-8")).compact();
        return jwt;
    } catch (UnsupportedEncodingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        return null;
    }
}

public boolean validateToken(String token) {
    String jwt = token;
    Jws<Claims> claims;
    try {
        claims = Jwts.parser().setSigningKey(secret.getBytes("UTF-8")).parseClaimsJws(jwt);
        userId = (Integer) claims.getBody().get("userId");
        loginId = (String) claims.getBody().get("loginId");
        emailId = (String) claims.getBody().get("emailId");
        return true;
    } catch (ExpiredJwtException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (UnsupportedJwtException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (MalformedJwtException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (SignatureException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IllegalArgumentException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (UnsupportedEncodingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
    return false;
}}

我的问题是

1. 为什么会这样

2. 如果它不安全，那么我们为什么要使用它

3. 有没有办法保护这个代币