SignInUtils.java

package io.loli.box.social;

import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.context.SecurityContextHolder;

public class SignInUtils {
    public static void signin(String userId) {
        SecurityContextHolder.getContext().setAuthentication(new UsernamePasswordAuthenticationToken(userId, null, null));
    }
}