一、基本思路

服务端通过 JSON字符串，告诉前端用户是否登录、认证；前端根据这些提示跳转对应的登录页、认证页

二、具体实现

AuthenticationEntryPoint：未登录

public class AjaxAuthenticationEntryPoint implements AuthenticationEntryPoint {
    @Override
    public void commence(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, AuthenticationException e) throws IOException, ServletException {
       
        AjaxResponseBody responseBody = new AjaxResponseBody();

        responseBody.setStatus("000");
        
        responseBody.setMsg("无访问权限，请先登录");

        httpServletResponse.getWriter().write(JSON.toJSONString(responseBody));
    }
}

AuthenticationFailureHandler：登录失败

public class AjaxAuthenticationFailureHandler implements AuthenticationFailureHandler {
    @Override
    public void onAuthenticationFailure(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, AuthenticationException e) throws IOException, ServletException {
        
        AjaxResponseBody responseBody = new AjaxResponseBody();

        responseBody.setStatus("400");
       
        responseBody.setMsg("登录失败");

        httpServletResponse.getWriter().write(JSON.toJSONString(responseBody));
    }
}

AuthenticationSuccessHandler ：登录成功

public class AjaxAuthenticationSuccessHandler implements AuthenticationSuccessHandler {
    @Override
    public void onAuthenticationSuccess(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Authentication authentication) throws IOException, ServletException {
        
        AjaxResponseBody responseBody = new AjaxResponseBody();

        responseBody.setStatus("200");
       
        responseBody.setMsg("登录成功");

        httpServletResponse.getWriter().write(JSON.toJSONString(responseBody));
    }
}

AccessDeniedHandler：无权访问

public class AjaxAccessDeniedHandler implements AccessDeniedHandler {
    @Override
    public void handle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, AccessDeniedException e) throws IOException, ServletException {
        
        AjaxResponseBody responseBody = new AjaxResponseBody();

        responseBody.setStatus("300");
       
        responseBody.setMsg("无权访问");

        httpServletResponse.getWriter().write(JSON.toJSONString(responseBody));
    }
}

LogoutSuccessHandler：注销

public class AjaxLogoutSuccessHandler implements LogoutSuccessHandler {
    @Override
    public void onLogoutSuccess(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Authentication authentication) throws IOException, ServletException {
        
        AjaxResponseBody responseBody = new AjaxResponseBody();

        responseBody.setStatus("100");
        
        responseBody.setMsg("注销成功");

        httpServletResponse.getWriter().write(JSON.toJSONString(responseBody));
    }
}

UserDetails:定义User对象

public class SelfUserDetails implements UserDetails, Serializable {
    private String username;
    private String password;
    private Set<? extends GrantedAuthority> authorities;

    @Override
    public Collection<? extends GrantedAuthority> getAuthorities() {
        return this.authorities;
    }

    public void setAuthorities(Set<? extends GrantedAuthority> authorities) {
        this.authorities = authorities;
    }

    @Override
    public String getPassword() { 
        return this.password;
    }

    @Override
    public String getUsername() {
        return this.username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public boolean isAccountNonExpired() {
        return true;
    }

    @Override
    public boolean isAccountNonLocked() {
        return true;
    }

    @Override
    public boolean isCredentialsNonExpired() {
        return true;
    }

    @Override
    public boolean isEnabled() {
        return true;
    }
}

UserDetailsService：用户权限认证

public class SelfUserDetailsService implements UserDetailsService {
    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
        SelfUserDetails userInfo = new SelfUserDetails();
        userInfo.setUsername(username);
        Md5PasswordEncoder md5PasswordEncoder = new Md5PasswordEncoder();
        String encodePassword = md5PasswordEncoder.encodePassword("123", username); 
        userInfo.setPassword(encodePassword);
        Set authoritiesSet = new HashSet();
        GrantedAuthority authority = new SimpleGrantedAuthority("ROLE_ADMIN"); 
        authoritiesSet.add(authority);
        userInfo.setAuthorities(authoritiesSet);
        return userInfo;
    }
}

AuthenticationProvider：前端交互

public class SelfAuthenticationProvider implements AuthenticationProvider {
    @Autowired
    SelfUserDetailsService userDetailsService;

    @Override
    public Authentication authenticate(Authentication authentication) throws AuthenticationException {
        String userName = (String) authentication.getPrincipal();
        String password = (String) authentication.getCredentials(); 

        Md5PasswordEncoder md5PasswordEncoder = new Md5PasswordEncoder();
        String encodePwd = md5PasswordEncoder.encodePassword(password, userName);

        UserDetails userInfo = userDetailsService.loadUserByUsername(userName);

        if (!userInfo.getPassword().equals(encodePwd)) {
            throw new BadCredentialsException("用户名密码不正确，请重新登陆！");
        }

        return new UsernamePasswordAuthenticationToken(userName, password, userInfo.getAuthorities());
    }

    @Override
    public boolean supports(Class<?> authentication) {
        return true;
    }
}

WebSecurityConfigurerAdapter：登录拦截全局配置

public class SpringSecurityConf extends WebSecurityConfigurerAdapter {

    @Autowired
    AjaxAuthenticationEntryPoint authenticationEntryPoint;  //  未登陆时返回 JSON 格式的数据给前端（否则为 html）

    @Autowired
    AjaxAuthenticationSuccessHandler authenticationSuccessHandler;  // 登录成功返回的 JSON 格式数据给前端（否则为 html）

    @Autowired
    AjaxAuthenticationFailureHandler authenticationFailureHandler;  //  登录失败返回的 JSON 格式数据给前端（否则为 html）

    @Autowired
    AjaxLogoutSuccessHandler  logoutSuccessHandler;  // 注销成功返回的 JSON 格式数据给前端（否则为 登录时的 html）

    @Autowired
    AjaxAccessDeniedHandler accessDeniedHandler;    // 无权访问返回的 JSON 格式数据给前端（否则为 403 html 页面）

    @Autowired
    SelfAuthenticationProvider provider; // 自定义安全认证

    @Override
    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
        // 加入自定义的安全认证
        auth.authenticationProvider(provider);
    }

    @Override
    protected void configure(HttpSecurity http) throws Exception {

        http.csrf().disable()

                .httpBasic().authenticationEntryPoint(authenticationEntryPoint)

                .and()
                .authorizeRequests()

                .anyRequest()
                .authenticated()// 其他 url 需要身份认证

                .and()
                .formLogin()  //开启登录
                .successHandler(authenticationSuccessHandler) // 登录成功
                .failureHandler(authenticationFailureHandler) // 登录失败
                .permitAll()

                .and()
                .logout()
                .logoutSuccessHandler(logoutSuccessHandler)
                .permitAll();

        http.exceptionHandling().accessDeniedHandler(accessDeniedHandler); // 无权访问 JSON 格式的数据

    }
}