用Spring Security+jwt 写个登录验证

1. 首先添加Spring Security JWT依赖：

<dependency>
    <groupId>io.jsonwebtoken</groupId>
    <artifactId>jjwt</artifactId>
    <version>0.9.1</version>
</dependency>

2. 创建一个JWT工具类来生成和验证JWT：

import io.jsonwebtoken.Claims;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;
import io.jsonwebtoken.security.Keys;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.stereotype.Component;

import java.security.Key;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.function.Function;

@Component
public class JwtUtil {

    private final String SECRET_KEY = "my-secret-key"; // 随便设置一个密钥

    private final Key KEY = Keys.hmacShaKeyFor(SECRET_KEY.getBytes());

    public String generateToken(UserDetails userDetails) {
        Map<String, Object> claims = new HashMap<>();
        return createToken(claims, userDetails.getUsername());
    }

    private String createToken(Map<String, Object> claims, String subject) {
        Date now = new Date();
        Date expiration = new Date(now.getTime() + 1000 * 60 * 60 * 10); // 设置过期时间为10小时
        return Jwts.builder()
                .setClaims(claims)
                .setSubject(subject)
                .setIssuedAt(now)
                .setExpiration(expiration)
                .signWith(KEY, SignatureAlgorithm.HS256)
                .compact();
    }

    public Boolean validateToken(String token, UserDetails userDetails) {
        final String username = extractUsername(token);
        return (username.equals(userDetails.getUsername()) && !isTokenExpired(token));
    }

    public String extractUsername(String token) {
        return extractClaim(token, Claims::getSubject);
    }

    public Date extractExpiration(String token) {
        return extractClaim(token, Claims::getExpiration);
    }

    public <T> T extractClaim(String token, Function<Claims, T> claimsResolver) {
        final Claims claims = extractAllClaims(token);
        return claimsResolver.apply(claims);
    }

    private Claims extractAllClaims(String token) {
        return Jwts.parserBuilder().setSigningKey(KEY).build().parseClaimsJws(token).getBody();
    }

    private Boolean isTokenExpired(String token) {
        return extractExpiration(token).before(new Date());
    }
}

3. 创建一个实现UserDetailsService接口的类来从数据库中获取用户信息：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.core.userdetails.User;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.core.userdetails.UsernameNotFoundException;
import org.springframework.stereotype.Service;

@Service
public class MyUserDetailsService implements UserDetailsService {

    @Autowired
    private UserRepository userRepository;

    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
        UserEntity userEntity = userRepository.findByUsername(username);
        if (userEntity == null) {
            throw new UsernameNotFoundException("User not found with username: " + username);
        }
        return new User(userEntity.getUsername(), userEntity.getPassword(), userEntity.getAuthorities());
    }
}

4. 创建一个Controller来处理登录请求，并返回JWT：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.AuthenticationException;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class AuthenticationController {

    @Autowired
    private AuthenticationManager authenticationManager;

    @Autowired
    private JwtUtil jwtUtil;

    @Autowired
    private MyUserDetailsService userDetailsService;

    @PostMapping("/authenticate")
    public ResponseEntity<?> createAuthenticationToken(@RequestBody AuthenticationRequest authenticationRequest) throws Exception {
        try {
            authenticationManager.authenticate(
                    new UsernamePasswordAuthenticationToken(authenticationRequest.getUsername(), authenticationRequest.getPassword())
            );
        } catch (AuthenticationException e) {
            throw new Exception("Incorrect username or password", e);
        }

        final UserDetails userDetails = userDetailsService.loadUserByUsername(authenticationRequest.getUsername());
        final String jwt = jwtUtil.generateToken(userDetails);

        return ResponseEntity.ok(new AuthenticationResponse(jwt));
    }
}

5. 创建一个Filter来验证请求中的JWT：

import io.jsonwebtoken.ExpiredJwtException;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.web.filter.OncePerRequestFilter;

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

public class JwtRequestFilter extends OncePerRequestFilter {

    @Autowired
    private UserDetailsService userDetailsService;

    @Autowired
    private JwtUtil jwtUtil;

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws ServletException, IOException {
        final String authorizationHeader = request.getHeader("Authorization");

        String username = null;
        String jwt = null;

        if (authorizationHeader != null && authorizationHeader.startsWith("Bearer ")) {
            jwt = authorizationHeader.substring(7);
            try {
                username = jwtUtil.extractUsername(jwt);
            } catch (ExpiredJwtException e) {
                response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
                response.getWriter().write("Token expired");
                return;
            }
        }

        if (username != null && SecurityContextHolder.getContext().getAuthentication() == null) {
            UserDetails userDetails = this.userDetailsService.loadUserByUsername(username);
            if (jwtUtil.validateToken(jwt, userDetails)) {
                UsernamePasswordAuthenticationToken usernamePasswordAuthenticationToken = new UsernamePasswordAuthenticationToken(
                        userDetails, null, userDetails.getAuthorities()
                );
                SecurityContextHolder.getContext().setAuthentication(usernamePasswordAuthenticationToken);
            } else {
                response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
                response.getWriter().write("Invalid token");
                return;
            }
        }

        chain.doFilter(request, response);
    }
}

6. 在Security配置中使用上述Filter：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.HttpMethod;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
import org.springframework.security.config.annotation.method.configuration.EnableGlobalMethodSecurity;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import org.springframework.security.crypto.password.PasswordEncoder;
import org.springframework.security.web.authentication.UsernamePasswordAuthenticationFilter;

@Configuration
@EnableWebSecurity
@EnableGlobalMethodSecurity(prePostEnabled = true)
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Autowired
    private JwtRequestFilter jwtRequestFilter;

    @Autowired
    private UserDetailsService userDetailsService;

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.csrf().disable()
                .authorizeRequests()
                .antMatchers(HttpMethod.POST, "/authenticate").permitAll()
                .anyRequest().authenticated();

        http.addFilterBefore(jwtRequestFilter, UsernamePasswordAuthenticationFilter.class);
    }

    @Autowired
    public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {
        auth.userDetailsService(userDetailsService).passwordEncoder(passwordEncoder());
    }

    @Bean
    public PasswordEncoder passwordEncoder() {
        return new BCryptPasswordEncoder();
    }

    @Bean
    public AuthenticationManager authenticationManagerBean() throws Exception {
        return super.authenticationManagerBean();
    }
}

这样，我们就成功地使用Spring Security JWT实现了登录验证。