解释这段代码 public static User getSubject() { User user = (User) SecurityUtils.getSubject().getPrincipal(); // 初始化延迟加载的部门信息 if (user != null && !Hibernate.isInitialized(user.getDept())) { try { Hibernate.initialize(user.getDept()); } catch (LazyInitializationException e) { UserService userService = SpringContextUtil.getBean(UserService.class); User reload = userService.getById(user.getId()); Hibernate.initialize(reload.getDept()); BeanUtils.copyProperties(reload, user, "roles"); } } return user; }

这段代码是一个静态方法，返回一个 User 对象，表示当前登录用户。这里使用了 Shiro 框架的 SecurityUtils 工具类获取当前登录用户的信息，其中 getPrincipal() 方法返回的是 Object 类型，需要强制类型转换成 User 类型。接下来，代码对用户的部门信息进行处理。如果用户不为 null，而且用户的部门信息是延迟加载的，那么就使用 Hibernate.initialize() 方法将其初始化。如果在初始化部门信息时发生了 LazyInitializationException 异常，说明该用户的部门信息没有被正确加载，那么就需要重新查询用户信息并初始化部门信息，最后将查询出的用户信息复制到原来的用户对象中（排除 roles 属性）。最终返回处理后的用户对象。

相关问题

public class ShiroUtils { public static Session getSession() { return SecurityUtils.getSubject().getSession(); } public static Subject getSubject() { return SecurityUtils.getSubject(); } public static SysUser getUserEntity() { return (SysUser)SecurityUtils.getSubject().getPrincipal(); } public static Long getUserId() { return getUserEntity().getUserId(); } public static void setSessionAttribute(Object key, Object value) { getSession().setAttribute(key, value); } public static Object getSessionAttribute(Object key) { return getSession().getAttribute(key); } public static boolean isLogin() { return SecurityUtils.getSubject().getPrincipal() != null; } public static void logout() { SecurityUtils.getSubject().logout(); } public static boolean isHasRole(String roleSign) { return SecurityUtils.getSubject().hasRole(roleSign); } }

这是一个Shiro权限框架相关的工具类，其中包含了一些常用的操作方法，比如 getSession、getSubject、getUserEntity、getUserId、setSessionAttribute、getSessionAttribute、isLogin、logout、isHasRole。这些方法可以方便地获取当前用户的信息，判断用户是否登录，以及查询用户是否拥有某个角色等操作。Shiro是一个非常强大的安全框架，可以帮助我们快速地实现权限控制功能。

springboot security项目 如何封装jwt 及token 其中数据表为package com.aokace.entity; import com.baomidou.mybatisplus.annotation.IdType; import com.baomidou.mybatisplus.annotation.TableField; import com.baomidou.mybatisplus.annotation.TableId; import com.baomidou.mybatisplus.annotation.TableName; import java.io.Serializable; import io.swagger.annotations.ApiModel; import io.swagger.annotations.ApiModelProperty; import lombok.Getter; import lombok.Setter; /** * <p> * * </p> * * @author aokace * @since 2023-05-23 */ @Getter @Setter @TableName("user") @ApiModel(value = "User对象", description = "") public class User implements Serializable { private static final long serialVersionUID = 1L; @TableId(value = "userid", type = IdType.AUTO) private Integer userid; @TableField("authority") private String authority; @TableField("role") private String role; @TableField("username") private String username; @TableField("password") private String password; }

首先需要引入相关的依赖，包括JWT和Spring Security的依赖：

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

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

然后创建一个JwtTokenUtil类来实现JWT的签发和验证功能：

import io.jsonwebtoken.Claims;
import io.jsonwebtoken.JwtBuilder;
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;

@Component
public class JwtTokenUtil {

    private static final String CLAIM_KEY_USERNAME = "sub";
    private static final String CLAIM_KEY_CREATED = "created";

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

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

    public String generateToken(UserDetails userDetails) {
        Map<String, Object> claims = new HashMap<>();
        claims.put(CLAIM_KEY_USERNAME, userDetails.getUsername());
        claims.put(CLAIM_KEY_CREATED, new Date());
        return generateToken(claims);
    }

    public String getUsernameFromToken(String token) {
        String username;
        try {
            Claims claims = getClaimsFromToken(token);
            username = claims.getSubject();
        } catch (Exception e) {
            username = null;
        }
        return username;
    }

    public Date getCreatedDateFromToken(String token) {
        Date created;
        try {
            Claims claims = getClaimsFromToken(token);
            created = new Date((Long) claims.get(CLAIM_KEY_CREATED));
        } catch (Exception e) {
            created = null;
        }
        return created;
    }

    public Date getExpirationDateFromToken(String token) {
        Date expiration;
        try {
            Claims claims = getClaimsFromToken(token);
            expiration = claims.getExpiration();
        } catch (Exception e) {
            expiration = null;
        }
        return expiration;
    }

    public boolean isTokenExpired(String token) {
        Date expiration = getExpirationDateFromToken(token);
        return expiration.before(new Date());
    }

    public String refreshToken(String token) {
        String refreshedToken;
        try {
            Claims claims = getClaimsFromToken(token);
            claims.put(CLAIM_KEY_CREATED, new Date());
            refreshedToken = generateToken(claims);
        } catch (Exception e) {
            refreshedToken = null;
        }
        return refreshedToken;
    }

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

    private Claims getClaimsFromToken(String token) {
        Claims claims;
        try {
            claims = Jwts.parser()
                    .setSigningKey(secret)
                    .parseClaimsJws(token)
                    .getBody();
        } catch (Exception e) {
            claims = null;
        }
        return claims;
    }

    private String generateToken(Map<String, Object> claims) {
        Date expirationDate = new Date(System.currentTimeMillis() + expiration * 1000);
        JwtBuilder builder = Jwts.builder()
                .setClaims(claims)
                .setExpiration(expirationDate)
                .signWith(SignatureAlgorithm.HS512, secret);
        return builder.compact();
    }
}

其中，JwtTokenUtil类中的generateToken方法用于生成JWT Token，getUsernameFromToken和getExpirationDateFromToken方法用于解析JWT Token中的用户名和过期时间，isTokenExpired方法用于判断JWT Token是否已经过期，refreshToken方法用于刷新JWT Token，validateToken方法用于验证JWT Token是否有效，getClaimsFromToken方法用于从JWT Token中获取Claims。

然后在Spring Security的配置类中添加JwtTokenFilter来实现JWT的过滤和验证：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
import org.springframework.security.config.annotation.method.configuration.EnableGlobalMethodSecurity;
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.Authentication;
import org.springframework.security.core.AuthenticationException;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import org.springframework.security.web.authentication.UsernamePasswordAuthenticationFilter;

@Configuration
@EnableWebSecurity
@EnableGlobalMethodSecurity(prePostEnabled = true)
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Autowired
    private UserDetailsService userDetailsService;

    @Autowired
    private JwtTokenFilter jwtTokenFilter;

    @Autowired
    private JwtAuthenticationEntryPoint jwtAuthenticationEntryPoint;

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

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

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

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

其中，SecurityConfig类中的configure方法用于配置Spring Security的策略，addFilterBefore方法用于添加JwtTokenFilter，authenticationManagerBean方法用于获取AuthenticationManager。

最后，在登录接口中，使用JwtTokenUtil生成JWT Token并返回给前端：

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.Authentication;
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 AuthController {

    @Autowired
    private AuthenticationManager authenticationManager;

    @Autowired
    private JwtTokenUtil jwtTokenUtil;

    @Autowired
    private UserDetailsService userDetailsService;

    @PostMapping("/login")
    public ResponseEntity<?> login(@RequestBody AuthRequest authRequest) throws Exception {
        try {
            Authentication authentication = authenticationManager.authenticate(
                    new UsernamePasswordAuthenticationToken(authRequest.getUsername(), authRequest.getPassword())
            );
            UserDetails userDetails = userDetailsService.loadUserByUsername(authRequest.getUsername());
            String token = jwtTokenUtil.generateToken(userDetails);
            return ResponseEntity.ok(new AuthResponse(token));
        } catch (Exception e) {
            throw new Exception("Incorrect username or password", e);
        }
    }
}

其中，AuthController类中的login方法用于处理登录请求，通过authenticationManager.authenticate方法验证用户名和密码，然后使用JwtTokenUtil生成JWT Token并返回给前端。