JWTFilter.java

package io.github.jhipster.sample.security.jwt;

/*-
 * #%L
 * Jhipster Sample Application
 * %%
 * Copyright (C) 2017 Osgiliath
 * %%
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * #L%
 */

import org.springframework.security.core.Authentication;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.util.StringUtils;
import org.springframework.web.filter.GenericFilterBean;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

/**
 * Filters incoming requests and installs a Spring Security principal if a header corresponding to a valid user is
 * found.
 */
public class JWTFilter extends GenericFilterBean {

    private TokenProvider tokenProvider;

    public JWTFilter(TokenProvider tokenProvider) {
        this.tokenProvider = tokenProvider;
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
        throws IOException, ServletException {
        HttpServletRequest httpServletRequest = (HttpServletRequest) servletRequest;
        String jwt = resolveToken(httpServletRequest);
        if (StringUtils.hasText(jwt) && this.tokenProvider.validateToken(jwt)) {
            Authentication authentication = this.tokenProvider.getAuthentication(jwt);
            SecurityContextHolder.getContext().setAuthentication(authentication);
        }
        filterChain.doFilter(servletRequest, servletResponse);
    }

    private String resolveToken(HttpServletRequest request){
        String bearerToken = request.getHeader(JWTConfigurer.AUTHORIZATION_HEADER);
        if (StringUtils.hasText(bearerToken) && bearerToken.startsWith("Bearer ")) {
            return bearerToken.substring(7, bearerToken.length());
        }
        return null;
    }
}