帮我写一下基于Spring Security的登录系统

好的，我可以为您提供关于基于Spring Security的登录系统的编程建议。首先，您需要在您的Spring应用程序中引入Spring Security依赖项。接下来，您需要配置安全性设置和认证提供程序，以便用户可以进行身份验证和访问授权内容。您还可以添加一些过滤器和拦截器，以便对用户请求进行更严格的安全性策略控制。最后，您可以使用Spring Security的API编写自定义的登录处理逻辑，以便您的用户可以通过自定义的表单或第三方身份验证服务进行登录。希望这可以帮助您开始编写Spring Security的登录系统！

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帮我写一个基于springboot+springsecurity+jwt的权限管理系统

好的，下面是一个基于Spring Boot、Spring Security和JWT的权限管理系统的代码框架。

1. 首先，引入相关的依赖：

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

    <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>
</dependencies>

2. 编写JWT工具类：

@Component
public class JwtUtils {
    private static final String SECRET_KEY = "my_secret_key";
    private static final long EXPIRATION_TIME = 864_000_000L;

    public String generateToken(String username) {
        Date expirationDate = new Date(System.currentTimeMillis() + EXPIRATION_TIME);

        String token = Jwts.builder()
                .setSubject(username)
                .setExpiration(expirationDate)
                .signWith(SignatureAlgorithm.HS512, SECRET_KEY)
                .compact();
        return token;
    }

    public String getUsernameFromToken(String token) {
        try {
            Claims claims = Jwts.parser()
                    .setSigningKey(SECRET_KEY)
                    .parseClaimsJws(token)
                    .getBody();

            return claims.getSubject();
        } catch (Exception e) {
            return null;
        }
    }

    public boolean isValidToken(String token) {
        try {
            Jwts.parser().setSigningKey(SECRET_KEY).parseClaimsJws(token);
            return true;
        } catch (Exception e) {
            return false;
        }
    }
}

3. 编写自定义UserDetailsService：

@Service
public class CustomUserDetailsService 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(),
                new ArrayList<>()
        );
    }
}

4. 配置Spring Security：

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
    @Autowired
    private CustomUserDetailsService userDetailsService;

    @Autowired
    private JwtUtils jwtUtils;

    @Autowired
    private UnauthorizedHandler unauthorizedHandler;

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.csrf().disable().authorizeRequests()
            .antMatchers(HttpMethod.POST, "/users/login").permitAll()
            .anyRequest().authenticated()
            .and()
            .exceptionHandling()
            .authenticationEntryPoint(unauthorizedHandler)
            .and()
            .sessionManagement()
            .sessionCreationPolicy(SessionCreationPolicy.STATELESS);

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

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

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

    @Bean
    public JwtAuthenticationFilter jwtAuthenticationFilter() {
        return new JwtAuthenticationFilter(jwtUtils, userDetailsService);
    }
}

在这个配置中，我们使用了JwtAuthenticationFilter来处理JWT的校验和授权。UnauthorizedHandler则用来处理未授权的情况。

5. 编写JwtAuthenticationFilter：

public class JwtAuthenticationFilter extends OncePerRequestFilter {
    @Autowired
    private JwtUtils jwtUtils;

    @Autowired
    private CustomUserDetailsService userDetailsService;

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain chain)
            throws ServletException, IOException {

        String authorizationHeader = request.getHeader("Authorization");

        String username = null;
        String token = null;

        if (authorizationHeader != null && authorizationHeader.startsWith("Bearer ")) {
            token = authorizationHeader.substring(7);
            username = jwtUtils.getUsernameFromToken(token);
        }

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

            if (jwtUtils.isValidToken(token)) {
                UsernamePasswordAuthenticationToken authentication = new UsernamePasswordAuthenticationToken(
                        userDetails, null, userDetails.getAuthorities());
                authentication.setDetails(new WebAuthenticationDetailsSource().buildDetails(request));
                SecurityContextHolder.getContext().setAuthentication(authentication);
            }
        }

        chain.doFilter(request, response);
    }
}

6. 编写UnauthorizedHandler：

@Component
public class UnauthorizedHandler implements AuthenticationEntryPoint {
    @Override
    public void commence(HttpServletRequest request, HttpServletResponse response, AuthenticationException authException)
            throws IOException, ServletException {

        response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Unauthorized");
    }
}

7. 编写UserController：

@RestController
@RequestMapping("/users")
public class UserController {
    @Autowired
    private UserRepository userRepository;

    @Autowired
    private JwtUtils jwtUtils;

    @PostMapping("/signup")
    public ResponseEntity<?> signUp(@RequestBody User user) {
        User existingUser = userRepository.findByUsername(user.getUsername());

        if (existingUser != null) {
            return new ResponseEntity<>("Username already exists", HttpStatus.BAD_REQUEST);
        }

        user.setPassword(new BCryptPasswordEncoder().encode(user.getPassword()));
        userRepository.save(user);

        return ResponseEntity.ok("User created successfully");
    }

    @PostMapping("/login")
    public ResponseEntity<?> login(@RequestBody User user) {
        try {
            Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
            if (authentication != null && authentication.isAuthenticated()) {
                return ResponseEntity.ok("User already authenticated");
            }

            authenticationManager.authenticate(new UsernamePasswordAuthenticationToken(
                    user.getUsername(), user.getPassword()));
            final String token = jwtUtils.generateToken(user.getUsername());

            return ResponseEntity.ok(token);
        } catch (BadCredentialsException e) {
            return new ResponseEntity<>("Invalid username/password supplied", HttpStatus.UNAUTHORIZED);
        }
    }
}

这里的User类是一个简单的POJO，包含了username和password字段。

现在，就可以使用这个权限管理系统了。在前端请求中，需要在Header中传递一个Authorization的键值对，键是Bearer加上空格，值是JWT Token。这样就可以在Spring Security中进行授权了。

Spring Security写一个权限管理系统

好的，我可以为您提供一个基于 Spring Security 的权限管理系统的实现方案。首先，您需要定义用户角色和权限，然后在 Spring Security 中配置相应的安全策略。您可以使用基于数据库或者基于注解的方式来定义安全策略。在实现过程中，您需要使用 Spring Security 提供的注解来标识需要进行权限控制的方法或者资源。最后，您需要实现一个自定义的 UserDetailsService 来加载用户信息，并在登录时进行验证。如果您需要更详细的实现方案，可以参考 Spring Security 官方文档或者相关的教程。