如何使用Spring Boot + Jwt

使用Spring Boot和Jwt进行身份验证可以保护您的应用程序免受未经授权的访问。下面是使用Spring Boot和Jwt进行身份验证的步骤：

1. 添加相关依赖

在 `pom.xml` 文件中添加以下依赖：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-security</artifactId>
</dependency>

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

2. 创建JwtUtils类

创建一个 `JwtUtils` 类，用于生成和解析Jwt令牌。以下是一个示例实现：

import io.jsonwebtoken.Claims;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.stereotype.Component;

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

@Component
public class JwtUtils {

    @Value("${jwt.secret}")
    private String secret;

    @Value("${jwt.expiration}")
    private Long expiration;

    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 expirationDate = new Date(now.getTime() + expiration);

        return Jwts.builder()
                .setClaims(claims)
                .setSubject(subject)
                .setIssuedAt(now)
                .setExpiration(expirationDate)
                .signWith(SignatureAlgorithm.HS256, secret)
                .compact();
    }

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

    public boolean isTokenExpired(String token) {
        final Date expirationDate = extractExpiration(token);
        return expirationDate.before(new Date());
    }

    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.parser().setSigningKey(secret).parseClaimsJws(token).getBody();
    }
}

3. 创建JwtRequestFilter

创建一个 `JwtRequestFilter` 类，用于拦截所有安全请求并验证Jwt令牌。以下是一个示例实现：

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.User;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
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 UserDetailsService userDetailsService;

    @Autowired
    private JwtUtils jwtUtils;

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) 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);
            username = jwtUtils.extractUsername(jwt);
        }

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

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

4. 创建JwtAuthenticationController

创建一个 `JwtAuthenticationController` 类，用于处理用户身份验证请求并返回Jwt令牌。以下是一个示例实现：

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.security.core.userdetails.UserDetailsService;
import org.springframework.security.crypto.password.PasswordEncoder;
import org.springframework.web.bind.annotation.*;

@RestController
public class JwtAuthenticationController {

    @Autowired
    private AuthenticationManager authenticationManager;

    @Autowired
    private UserDetailsService userDetailsService;

    @Autowired
    private JwtUtils jwtUtils;

    @Autowired
    private PasswordEncoder passwordEncoder;

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

        final UserDetails userDetails = userDetailsService.loadUserByUsername(jwtRequest.getUsername());

        final String token = jwtUtils.generateToken(userDetails);

        return ResponseEntity.ok(new JwtResponse(token));
    }

    @PostMapping("/register")
    public ResponseEntity<?> saveUser(@RequestBody UserDto userDto) {
        User user = new User(userDto.getUsername(), passwordEncoder.encode(userDto.getPassword()));
        userDetailsService.save(user);
        return ResponseEntity.ok(user);
    }
}

5. 配置WebSecurityConfigurerAdapter

最后，我们需要配置WebSecurityConfigurerAdapter以启用基于Jwt的身份验证。以下是一个示例实现：

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.core.userdetails.UserDetailsService;
import org.springframework.security.crypto.password.PasswordEncoder;
import org.springframework.security.web.authentication.UsernamePasswordAuthenticationFilter;

@Configuration
@EnableWebSecurity
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {

    @Autowired
    private JwtRequestFilter jwtRequestFilter;

    @Autowired
    private UserDetailsService userDetailsService;

    @Autowired
    private PasswordEncoder passwordEncoder;

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

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

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

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

现在，您的Spring Boot应用程序已经配置使用Jwt进行身份验证。