接着上一问，用代码展示

好的，以下是一个简单的使用Spring Security实现身份认证和授权的示例代码：

1. 添加Spring Security依赖

<dependency>
    <groupId>org.springframework.security</groupId>
    <artifactId>spring-security-web</artifactId>
    <version>5.4.1</version>
</dependency>
<dependency>
    <groupId>org.springframework.security</groupId>
    <artifactId>spring-security-config</artifactId>
    <version>5.4.1</version>
</dependency>

2. 创建一个实现UserDetailsService接口的类

@Service
public class UserDetailsServiceImpl implements UserDetailsService {

    @Autowired
    private UserRepository userRepository;

    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
        User user = userRepository.findByUsername(username);
        if (user == null) {
            throw new UsernameNotFoundException("User not found with username: " + username);
        }
        return new org.springframework.security.core.userdetails.User(user.getUsername(), user.getPassword(),
                getAuthority(user));
    }

    private Set<SimpleGrantedAuthority> getAuthority(User user) {
        Set<SimpleGrantedAuthority> authorities = new HashSet<>();
        user.getRoles().forEach(role -> {
            authorities.add(new SimpleGrantedAuthority("ROLE_" + role.getName()));
            role.getPermissions().forEach(permission -> {
                authorities.add(new SimpleGrantedAuthority(permission.getName()));
            });
        });
        return authorities;
    }
}

3. 配置Spring Security

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Autowired
    private UserDetailsService userDetailsService;

    @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("/api/auth/**").permitAll()
                .antMatchers("/api/admin/**").hasRole("ADMIN")
                .anyRequest().authenticated()
                .and()
                .exceptionHandling().authenticationEntryPoint(unauthorizedHandler).and()
                .sessionManagement().sessionCreationPolicy(SessionCreationPolicy.STATELESS);
        http.addFilterBefore(authenticationJwtTokenFilter(), UsernamePasswordAuthenticationFilter.class);
    }

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

4. 配置认证规则

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

5. 配置授权规则

@Override
protected void configure(HttpSecurity http) throws Exception {
    http.csrf().disable().authorizeRequests()
            .antMatchers("/api/auth/**").permitAll()
            .antMatchers("/api/admin/**").hasRole("ADMIN")
            .anyRequest().authenticated()
            .and()
            .exceptionHandling().authenticationEntryPoint(unauthorizedHandler).and()
            .sessionManagement().sessionCreationPolicy(SessionCreationPolicy.STATELESS);
    http.addFilterBefore(authenticationJwtTokenFilter(), UsernamePasswordAuthenticationFilter.class);
}

6. 配置其他属性

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

以上代码是一个简单的使用Spring Security实现身份认证和授权的示例，仅供参考。