<dependency>
    <groupId>io.jsonwebtoken</groupId>
    <artifactId>jjwt-api</artifactId>
    <version>0.11.2</version>
</dependency>
<dependency>
    <groupId>io.jsonwebtoken</groupId>
    <artifactId>jjwt-impl</artifactId>
    <version>0.11.2</version>
</dependency>

import io.jsonwebtoken.Claims;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;
import org.springframework.stereotype.Component;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
@Component
public class JwtUtils {
    private final String secret = "your_secret_key";
    private final long expirationTime = 86400000; // 1 day in milliseconds
    // 生成JWT令牌
    public String generateToken(String username) {
        Date now = new Date();
        Date expirationDate = new Date(now.getTime() + expirationTime);
        Map<String, Object> claims = new HashMap<>();
        claims.put("sub", username);
        return Jwts.builder()
                .setClaims(claims)
                .setIssuedAt(now)
                .setExpiration(expirationDate)
                .signWith(SignatureAlgorithm.HS512, secret)
                .compact();
    }
    // 從JWT令牌中提取用戶(hù)名
    public String extractUsername(String token) {
        Claims claims = Jwts.parser()
                .setSigningKey(secret)
                .parseClaimsJws(token)
                .getBody();
        return claims.getSubject();
    }
    // 驗(yàn)證JWT令牌
    public boolean validateToken(String token) {
        try {
            Jwts.parser().setSigningKey(secret).parseClaimsJws(token);
            return true;
        } catch (Exception e) {
            return false;
        }
    }
}

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.authentication.AuthenticationManager;
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
public class SecurityConfig extends WebSecurityConfigurerAdapter {
    private final JwtRequestFilter jwtRequestFilter;
    private final UserDetailsService userDetailsService;
    public SecurityConfig(JwtRequestFilter jwtRequestFilter, UserDetailsService userDetailsService) {
        this.jwtRequestFilter = jwtRequestFilter;
        this.userDetailsService = userDetailsService;
    }
    @Bean
    public PasswordEncoder passwordEncoder() {
        return new BCryptPasswordEncoder();
    }
    @Bean
    @Override
    public AuthenticationManager authenticationManagerBean() throws Exception {
        return super.authenticationManagerBean();
    }
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.csrf().disable()
            .authorizeRequests()
                .antMatchers("/authenticate").permitAll() // 放行認(rèn)證接口
                .anyRequest().authenticated() // 所有其他請(qǐng)求需要認(rèn)證
            .and()
                .sessionManagement().sessionCreationPolicy(SessionCreationPolicy.STATELESS);
        http.addFilterBefore(jwtRequestFilter, UsernamePasswordAuthenticationFilter.class);
    }
}

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.*;
@RestController
public class AuthController {
    private final AuthenticationManager authenticationManager;
    private final JwtUtils jwtUtils;
    private final UserDetailsService userDetailsService;
    @Autowired
    public AuthController(AuthenticationManager authenticationManager, JwtUtils jwtUtils, UserDetailsService userDetailsService) {
        this.authenticationManager = authenticationManager;
        this.jwtUtils = jwtUtils;
        this.userDetailsService =
 userDetailsService;
    }
    @PostMapping("/authenticate")
    public ResponseEntity<?> createAuthenticationToken(@RequestBody AuthRequest authenticationRequest) throws Exception {
        authenticate(authenticationRequest.getUsername(), authenticationRequest.getPassword());
        final UserDetails userDetails = userDetailsService.loadUserByUsername(authenticationRequest.getUsername());
        final String jwt = jwtUtils.generateToken(userDetails.getUsername());
        return ResponseEntity.ok(new AuthResponse(jwt));
    }
    private void authenticate(String username, String password) throws Exception {
        try {
            authenticationManager.authenticate(new UsernamePasswordAuthenticationToken(username, password));
        } catch (Exception e) {
            throw new Exception("Invalid username or password");
        }
    }
}

@RestController
public class ResourceController {
    @GetMapping("/hello")
    @PreAuthorize("hasRole('USER')")
    public String helloUser() {
        return "Hello, User!";
    }
    @GetMapping("/admin")
    @PreAuthorize("hasRole('ADMIN')")
    public String helloAdmin() {
        return "Hello, Admin!";
    }
}