如何授予对托管在Google Compute Engine的VM上的Java Web应用程序的访问权限

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;

public class AuthServlet extends HttpServlet {
    private static final String SECRET_KEY = "yourSecretKey";

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
        String token = request.getHeader("Authorization");
        if (token != null && token.startsWith("Bearer ")) {
            token = token.substring(7);
            try {
                String username = Jwts.parser().setSigningKey(SECRET_KEY).parseClaimsJws(token).getBody().getSubject();
                // 验证通过，处理请求
                response.getWriter().write("Hello, " + username);
            } catch (Exception e) {
                response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
                response.getWriter().write("Invalid token");
            }
        } else {
            response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
            response.getWriter().write("Missing token");
        }
    }
}