JWTAuthorizationFilter.java

package com.saltynote.service.security;

import com.auth0.jwt.exceptions.JWTVerificationException;
import com.auth0.jwt.interfaces.DecodedJWT;
import com.saltynote.service.domain.transfer.JwtUser;
import com.saltynote.service.service.JwtService;
import jakarta.servlet.FilterChain;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import lombok.RequiredArgsConstructor;
import org.springframework.lang.NonNull;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.stereotype.Component;
import org.springframework.web.filter.OncePerRequestFilter;

import java.io.IOException;
import java.util.Collections;

@Component
@RequiredArgsConstructor
public class JWTAuthorizationFilter extends OncePerRequestFilter {

    private final JwtService jwtService;

    @Override
    protected void doFilterInternal(@NonNull HttpServletRequest req, @NonNull HttpServletResponse res,
            @NonNull FilterChain chain) throws IOException, ServletException {
        String header = req.getHeader(SecurityConstants.AUTH_HEADER);

        if (header == null || !header.startsWith(SecurityConstants.TOKEN_PREFIX)) {
            chain.doFilter(req, res);
            return;
        }

        UsernamePasswordAuthenticationToken authentication = getAuthentication(req);

        SecurityContextHolder.getContext().setAuthentication(authentication);
        chain.doFilter(req, res);
    }

    private UsernamePasswordAuthenticationToken getAuthentication(HttpServletRequest request) {
        String token = request.getHeader(SecurityConstants.AUTH_HEADER);
        if (token == null)
            return null;
        DecodedJWT decodedJWT = null;
        try {
            // parse the token.
            decodedJWT = jwtService.verifyAccessToken(token);
            if (decodedJWT == null) {
                return null;
            }
        }
        catch (JWTVerificationException e) {
            return null;
        }

        return new UsernamePasswordAuthenticationToken(
                new JwtUser(decodedJWT.getClaim(SecurityConstants.CLAIM_KEY_USER_ID).asString(),
                        decodedJWT.getSubject()),
                null, Collections.emptyList());

    }

}