spring security认证代码

抱歉，作为语言模型AI，无法提供感性的代码，以下是供参考的spring security认证流程：

1. 配置spring security

在spring的xml配置文件中添加如下配置：

<security:http auto-config="true" use-expressions="true">
    <security:intercept-url pattern="/admin/**" access="hasRole('ROLE_ADMIN')"/>
    <security:form-login login-page="/login" default-target-url="/home"
        authentication-failure-url="/login?error" username-parameter="username"
        password-parameter="password"/>
    <security:logout logout-success-url="/login?logout"/>
    <security:csrf/>
</security:http>

2. 实现UserDetailsService接口

@Service
public class MyUserDetailsService implements UserDetailsService {
 
    @Autowired
    private UserDao userDao;
 
    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
 
        User user = userDao.findByUsername(username);
        if (user == null) {
            throw new UsernameNotFoundException("User not found");
        }
        return new org.springframework.security.core.userdetails.User(user.getUsername(), user.getPassword(),
                getAuthorities(user));
    }
 
    private static Collection<? extends GrantedAuthority> getAuthorities(User user) {
        List<GrantedAuthority> authorities = new ArrayList<>();
        for (Role role : user.getRoles()) {
            authorities.add(new SimpleGrantedAuthority(role.getName()));
        }
        return authorities;
    }
 
}

3. 实现UserDetails接口

@Entity
@Table(name = "users")
public class User implements UserDetails {
 
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;
 
    private String username;
    private String password;
 
    @ManyToMany(fetch = FetchType.EAGER)
    @JoinTable(
            name = "users_roles",
            joinColumns = @JoinColumn(
                    name = "user_id", referencedColumnName = "id"),
            inverseJoinColumns = @JoinColumn(
                    name = "role_id", referencedColumnName = "id"))
    private Set<Role> roles;
 
    // 省略 getter 和 setter 方法
 
    @Override
    public Collection<? extends GrantedAuthority> getAuthorities() {
        return roles.stream()
                .map(role -> new SimpleGrantedAuthority(role.getName()))
                .collect(Collectors.toList());
    }
 
    @Override
    public boolean isAccountNonExpired() {
        return true;
    }
 
    @Override
    public boolean isAccountNonLocked() {
        return true;
    }
 
    @Override
    public boolean isCredentialsNonExpired() {
        return true;
    }
 
    @Override
    public boolean isEnabled() {
        return true;
    }
 
}

4. 配置web.xml

<!-- Spring Security -->
<filter>
    <filter-name>springSecurityFilterChain</filter-name>
    <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
</filter>
 
<filter-mapping>
    <filter-name>springSecurityFilterChain</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

5. 认证流程

用户通过表单提交用户名和密码，spring security根据用户名调用MyUserDetailsService的loadUserByUsername方法获取用户信息，然后将用户信息和表单提交的密码进行比对，如果匹配，认证通过，否则认证失败。

6. 认证成功后处理

当认证成功后，spring security会将用户信息存储在SecurityContextHolder中，并将请求重定向到用户请求的页面或默认页面。

7. 登出流程

用户点击退出链接，spring security将清除SecurityContextHolder中的认证信息，并将请求重定向到登录页面。