如何在Spring Boot项目中集成JWT实现安全认证？

在Spring Boot项目中集成JWT实现安全认证是常见的需求。本文将详细介绍如何在Spring Boot项目中集成JWT，并通过一个完整的示例演示如何实现安全认证。

一、环境准备

首先，确保你的Spring Boot项目已经创建。然后，添加以下依赖到pom.xml文件中：

<dependencies>
    <!-- Spring Boot Starter Web -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <!-- Spring Boot Starter Security -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-security</artifactId>
    </dependency>

    <!-- JJWT for JWT handling -->
    <dependency>
        <groupId>io.jsonwebtoken</groupId>
        <artifactId>jjwt-api</artifactId>
        <version>0.11.5</version>
    </dependency>
    <dependency>
        <groupId>io.jsonwebtoken</groupId>
        <artifactId>jjwt-impl</artifactId>
        <version>0.11.5</version>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>io.jsonwebtoken</groupId>
        <artifactId>jjwt-jackson</artifactId>
        <version>0.11.5</version>
        <scope>runtime</scope>
    </dependency>

    <!-- Lombok for boilerplate code reduction -->
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <scope>provided</scope>
    </dependency>
</dependencies>

二、JWT工具类

接下来，我们创建一个JWT工具类，用于生成和解析JWT令牌。

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 static final Key SECRET_KEY = Keys.secretKeyFor(SignatureAlgorithm.HS256);
    private static final long EXPIRATION_TIME = 864_000_000; // 10 days

    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) {
        return Jwts.builder()
                .setClaims(claims)
                .setSubject(subject)
                .setIssuedAt(new Date(System.currentTimeMillis()))
                .setExpiration(new Date(System.currentTimeMillis() + EXPIRATION_TIME))
                .signWith(SECRET_KEY)
                .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);
    }

    private <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(SECRET_KEY)
                .build()
                .parseClaimsJws(token)
                .getBody();
    }

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

三、自定义UserDetailsService

为了加载用户信息，我们需要实现UserDetailsService接口。

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;

import java.util.ArrayList;

@Service
public class CustomUserDetailsService implements UserDetailsService {

    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
        // In a real application, you would load the user from a database
        if ("admin".equals(username)) {
            return new User("admin", "password", new ArrayList<>());
        } else {
            throw new UsernameNotFoundException("User not found with username: " + username);
        }
    }
}

四、配置Spring Security

接下来，配置Spring Security以使用JWT进行认证。

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
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.config.http.SessionCreationPolicy;
import org.springframework.security.crypto.password.NoOpPasswordEncoder;
import org.springframework.security.crypto.password.PasswordEncoder;
import org.springframework.security.web.authentication.UsernamePasswordAuthenticationFilter;

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Autowired
    private CustomUserDetailsService customUserDetailsService;

    @Autowired
    private JwtUtil jwtUtil;

    @Override
    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
        auth.userDetailsService(customUserDetailsService);
    }

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.csrf().disable()
                .authorizeRequests()
                .antMatchers("/authenticate").permitAll()
                .anyRequest().authenticated()
                .and()
                .sessionManagement().sessionCreationPolicy(SessionCreationPolicy.STATELESS);

        http.addFilterBefore(new JwtRequestFilter(jwtUtil, customUserDetailsService), UsernamePasswordAuthenticationFilter.class);
    }

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

    @Bean
    public PasswordEncoder passwordEncoder() {
        return NoOpPasswordEncoder.getInstance();
    }
}

五、JWT请求过滤器

创建一个过滤器来拦截请求并验证JWT令牌。

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.web.authentication.WebAuthenticationDetailsSource;
import org.springframework.stereotype.Component;
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;

@Component
public class JwtRequestFilter extends OncePerRequestFilter {

    @Autowired
    private JwtUtil jwtUtil;

    @Autowired
    private CustomUserDetailsService customUserDetailsService;

    @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) {
                logger.warn("JWT token has expired");
            }
        }

        if (username != null && SecurityContextHolder.getContext().getAuthentication() == null) {
            UserDetails userDetails = this.customUserDetailsService.loadUserByUsername(username);

            if (jwtUtil.validateToken(jwt, userDetails)) {
                UsernamePasswordAuthenticationToken usernamePasswordAuthenticationToken = new UsernamePasswordAuthenticationToken(
                        userDetails, null, userDetails.getAuthorities());
                usernamePasswordAuthenticationToken
                        .setDetails(new WebAuthenticationDetailsSource().buildDetails(request));
                SecurityContextHolder.getContext().setAuthentication(usernamePasswordAuthenticationToken);
            }
        }
        chain.doFilter(request, response);
    }
}

六、创建认证控制器

最后，创建一个控制器来处理认证请求。

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.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 CustomUserDetailsService customUserDetailsService;

    @PostMapping("/authenticate")
    public ResponseEntity<?> createAuthenticationToken(@RequestBody AuthenticationRequest authenticationRequest) throws Exception {
        authenticationManager.authenticate(
                new UsernamePasswordAuthenticationToken(authenticationRequest.getUsername(), authenticationRequest.getPassword())
        );

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

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

七、测试认证流程

你可以使用Postman或curl来测试认证流程。首先，发送一个POST请求到/authenticate端点，包含用户名和密码：

{
    "username": "admin",
    "password": "password"
}

如果认证成功，你将收到一个JWT令牌。然后，你可以使用这个令牌访问其他受保护的端点，只需在请求头中添加Authorization: Bearer <JWT>。

八、总结

通过以上步骤，我们成功在Spring Boot项目中集成了JWT，实现了安全认证。JWT提供了一种无状态、可扩展的身份验证机制，非常适合分布式系统和微服务架构。希望本文能帮助你理解和实现JWT在Spring Boot中的应用。如果有任何问题，欢迎在评论区讨论！