@Component
public class UserService {

    public UserBean getUser(String username) {
        // 没有此用户直接返回null
        if (! DataSource.getData().containsKey(username))
            return null;

        UserBean user = new UserBean();
        Map<String, String> detail = DataSource.getData().get(username);

        user.setUsername(username);
        user.setPassword(detail.get("password"));
        user.setRole(detail.get("role"));
        user.setPermission(detail.get("permission"));
        return user;
    }
}

public class UserBean {
    private String username;

    private String password;

    private String role;

    private String permission;

    public String getUsername() {
        return username;
    }

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

    public String getPassword() {
        return password;
    }

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

    public String getRole() {
        return role;
    }

    public void setRole(String role) {
        this.role = role;
    }

    public String getPermission() {
        return permission;
    }

    public void setPermission(String permission) {
        this.permission = permission;
    }
}

public class JWTUtil {

    // 过期时间5分钟
    private static final long EXPIRE_TIME = 5*60*1000;

    /**
     * 校验token是否正确
     * @param token 密钥
     * @param secret 用户的密码
     * @return 是否正确
     */
    public static boolean verify(String token, String username, String secret) {
        try {
            Algorithm algorithm = Algorithm.HMAC256(secret);
            JWTVerifier verifier = JWT.require(algorithm)
                    .withClaim("username", username)
                    .build();
            DecodedJWT jwt = verifier.verify(token);
            return true;
        } catch (Exception exception) {
            return false;
        }
    }

    /**
     * 获得token中的信息无需secret解密也能获得
     * @return token中包含的用户名
     */
    public static String getUsername(String token) {
        try {
            DecodedJWT jwt = JWT.decode(token);
            return jwt.getClaim("username").asString();
        } catch (JWTDecodeException e) {
            return null;
        }
    }

    /**
     * 生成签名,5min后过期
     * @param username 用户名
     * @param secret 用户的密码
     * @return 加密的token
     */
    public static String sign(String username, String secret) {
        try {
            Date date = new Date(System.currentTimeMillis()+EXPIRE_TIME);
            Algorithm algorithm = Algorithm.HMAC256(secret);
            // 附带username信息
            return JWT.create()
                    .withClaim("username", username)
                    .withExpiresAt(date)
                    .sign(algorithm);
        } catch (UnsupportedEncodingException e) {
            return null;
        }
    }
}

public class ResponseBean {
    
    // http 状态码
    private int code;

    // 返回信息
    private String msg;

    // 返回的数据
    private Object data;

    public ResponseBean(int code, String msg, Object data) {
        this.code = code;
        this.msg = msg;
        this.data = data;
    }

    public int getCode() {
        return code;
    }

    public void setCode(int code) {
        this.code = code;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

    public Object getData() {
        return data;
    }

    public void setData(Object data) {
        this.data = data;
    }
}

public class UnauthorizedException extends RuntimeException {
    public UnauthorizedException(String msg) {
        super(msg);
    }

    public UnauthorizedException() {
        super();
    }
}

@RestController
public class WebController {

    private static final Logger LOGGER = LogManager.getLogger(WebController.class);

    private UserService userService;

    @Autowired
    public void setService(UserService userService) {
        this.userService = userService;
    }

    @PostMapping("/login")
    public ResponseBean login(@RequestParam("username") String username,
                              @RequestParam("password") String password) {
        UserBean userBean = userService.getUser(username);
        if (userBean.getPassword().equals(password)) {
            return new ResponseBean(200, "Login success", JWTUtil.sign(username, password));
        } else {
            throw new UnauthorizedException();
        }
    }

    @GetMapping("/article")
    public ResponseBean article() {
        Subject subject = SecurityUtils.getSubject();
        if (subject.isAuthenticated()) {
            return new ResponseBean(200, "You are already logged in", null);
        } else {
            return new ResponseBean(200, "You are guest", null);
        }
    }

    @GetMapping("/require_auth")
    @RequiresAuthentication
    public ResponseBean requireAuth() {
        return new ResponseBean(200, "You are authenticated", null);
    }

    @GetMapping("/require_role")
    @RequiresRoles("admin")
    public ResponseBean requireRole() {
        return new ResponseBean(200, "You are visiting require_role", null);
    }

    @GetMapping("/require_permission")
    @RequiresPermissions(logical = Logical.AND, value = {"view", "edit"})
    public ResponseBean requirePermission() {
        return new ResponseBean(200, "You are visiting permission require edit,view", null);
    }

    @RequestMapping(path = "/401")
    @ResponseStatus(HttpStatus.UNAUTHORIZED)
    public ResponseBean unauthorized() {
        return new ResponseBean(401, "Unauthorized", null);
    }
}

@RestControllerAdvice
public class ExceptionController {

    // 捕捉shiro的异常
    @ResponseStatus(HttpStatus.UNAUTHORIZED)
    @ExceptionHandler(ShiroException.class)
    public ResponseBean handle401(ShiroException e) {
        return new ResponseBean(401, e.getMessage(), null);
    }

    // 捕捉UnauthorizedException
    @ResponseStatus(HttpStatus.UNAUTHORIZED)
    @ExceptionHandler(UnauthorizedException.class)
    public ResponseBean handle401() {
        return new ResponseBean(401, "Unauthorized", null);
    }

    // 捕捉其他所有异常
    @ExceptionHandler(Exception.class)
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    public ResponseBean globalException(HttpServletRequest request, Throwable ex) {
        return new ResponseBean(getStatus(request).value(), ex.getMessage(), null);
    }

    private HttpStatus getStatus(HttpServletRequest request) {
        Integer statusCode = (Integer) request.getAttribute("javax.servlet.error.status_code");
        if (statusCode == null) {
            return HttpStatus.INTERNAL_SERVER_ERROR;
        }
        return HttpStatus.valueOf(statusCode);
    }
}

public class JWTToken implements AuthenticationToken {

    // 密钥
    private String token;

    public JWTToken(String token) {
        this.token = token;
    }

    @Override
    public Object getPrincipal() {
        return token;
    }

    @Override
    public Object getCredentials() {
        return token;
    }
}

@Service
public class MyRealm extends AuthorizingRealm {

    private static final Logger LOGGER = LogManager.getLogger(MyRealm.class);

    private UserService userService;

    @Autowired
    public void setUserService(UserService userService) {
        this.userService = userService;
    }

    /**
     * 大坑！，必须重写此方法，不然Shiro会报错
     */
    @Override
    public boolean supports(AuthenticationToken token) {
        return token instanceof JWTToken;
    }

    /**
     * 只有当需要检测用户权限的时候才会调用此方法，例如checkRole,checkPermission之类的
     */
    @Override
    protected AuthorizationInfo doGetAuthorizationInfo(PrincipalCollection principals) {
        String username = JWTUtil.getUsername(principals.toString());
        UserBean user = userService.getUser(username);
        SimpleAuthorizationInfo simpleAuthorizationInfo = new SimpleAuthorizationInfo();
        simpleAuthorizationInfo.addRole(user.getRole());
        Set<String> permission = new HashSet<>(Arrays.asList(user.getPermission().split(",")));
        simpleAuthorizationInfo.addStringPermissions(permission);
        return simpleAuthorizationInfo;
    }

    /**
     * 默认使用此方法进行用户名正确与否验证，错误抛出异常即可。
     */
    @Override
    protected AuthenticationInfo doGetAuthenticationInfo(AuthenticationToken auth) throws AuthenticationException {
        String token = (String) auth.getCredentials();
        // 解密获得username，用于和数据库进行对比
        String username = JWTUtil.getUsername(token);
        if (username == null) {
            throw new AuthenticationException("token invalid");
        }

        UserBean userBean = userService.getUser(username);
        if (userBean == null) {
            throw new AuthenticationException("User didn't existed!");
        }

        if (! JWTUtil.verify(token, username, userBean.getPassword())) {
            throw new AuthenticationException("Username or password error");
        }

        return new SimpleAuthenticationInfo(token, token, "my_realm");
    }
}

public class JWTFilter extends BasicHttpAuthenticationFilter {

    private Logger LOGGER = LoggerFactory.getLogger(this.getClass());

    /**
     * 判断用户是否想要登入。
     * 检测header里面是否包含Authorization字段即可
     */
    @Override
    protected boolean isLoginAttempt(ServletRequest request, ServletResponse response) {
        HttpServletRequest req = (HttpServletRequest) request;
        String authorization = req.getHeader("Authorization");
        return authorization != null;
    }

    /**
     *
     */
    @Override
    protected boolean executeLogin(ServletRequest request, ServletResponse response) throws Exception {
        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        String authorization = httpServletRequest.getHeader("Authorization");

        JWTToken token = new JWTToken(authorization);
        // 提交给realm进行登入，如果错误他会抛出异常并被捕获
        getSubject(request, response).login(token);
        // 如果没有抛出异常则代表登入成功，返回true
        return true;
    }

    /**
     * 这里我们详细说明下为什么最终返回的都是true，即允许访问
     * 例如我们提供一个地址 GET /article
     * 登入用户和游客看到的内容是不同的
     * 如果在这里返回了false，请求会被直接拦截，用户看不到任何东西
     * 所以我们在这里返回true，Controller中可以通过 subject.isAuthenticated() 来判断用户是否登入
     * 如果有些资源只有登入用户才能访问，我们只需要在方法上面加上 @RequiresAuthentication 注解即可
     * 但是这样做有一个缺点，就是不能够对GET,POST等请求进行分别过滤鉴权(因为我们重写了官方的方法)，但实际上对应用影响不大
     */
    @Override
    protected boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object mappedValue) {
        if (isLoginAttempt(request, response)) {
            try {
                executeLogin(request, response);
            } catch (Exception e) {
                response401(request, response);
            }
        }
        return true;
    }

    /**
     * 对跨域提供支持
     */
    @Override
    protected boolean preHandle(ServletRequest request, ServletResponse response) throws Exception {
        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        HttpServletResponse httpServletResponse = (HttpServletResponse) response;
        httpServletResponse.setHeader("Access-control-Allow-Origin", httpServletRequest.getHeader("Origin"));
        httpServletResponse.setHeader("Access-Control-Allow-Methods", "GET,POST,OPTIONS,PUT,DELETE");
        httpServletResponse.setHeader("Access-Control-Allow-Headers", httpServletRequest.getHeader("Access-Control-Request-Headers"));
        // 跨域时会首先发送一个option请求，这里我们给option请求直接返回正常状态
        if (httpServletRequest.getMethod().equals(RequestMethod.OPTIONS.name())) {
            httpServletResponse.setStatus(HttpStatus.OK.value());
            return false;
        }
        return super.preHandle(request, response);
    }

    /**
     * 将非法请求跳转到 /401
     */
    private void response401(ServletRequest req, ServletResponse resp) {
        try {
            HttpServletResponse httpServletResponse = (HttpServletResponse) resp;
            httpServletResponse.sendRedirect("/401");
        } catch (IOException e) {
            LOGGER.error(e.getMessage());
        }
    }
}

@Configuration
public class ShiroConfig {

    @Bean("securityManager")
    public DefaultWebSecurityManager getManager(MyRealm realm) {
        DefaultWebSecurityManager manager = new DefaultWebSecurityManager();
        // 使用自己的realm
        manager.setRealm(realm);

        /*
         * 关闭shiro自带的session，详情见文档
         * http://shiro.apache.org/session-management.html#SessionManagement-StatelessApplications%28Sessionless%29
         */
        DefaultSubjectDAO subjectDAO = new DefaultSubjectDAO();
        DefaultSessionStorageEvaluator defaultSessionStorageEvaluator = new DefaultSessionStorageEvaluator();
        defaultSessionStorageEvaluator.setSessionStorageEnabled(false);
        subjectDAO.setSessionStorageEvaluator(defaultSessionStorageEvaluator);
        manager.setSubjectDAO(subjectDAO);

        return manager;
    }

    @Bean("shiroFilter")
    public ShiroFilterFactoryBean factory(DefaultWebSecurityManager securityManager) {
        ShiroFilterFactoryBean factoryBean = new ShiroFilterFactoryBean();

        // 添加自己的过滤器并且取名为jwt
        Map<String, Filter> filterMap = new HashMap<>();
        filterMap.put("jwt", new JWTFilter());
        factoryBean.setFilters(filterMap);

        factoryBean.setSecurityManager(securityManager);
        factoryBean.setUnauthorizedUrl("/401");

        /*
         * 自定义url规则
         * http://shiro.apache.org/web.html#urls-
         */
        Map<String, String> filterRuleMap = new HashMap<>();
        // 所有请求通过我们自己的JWT Filter
        filterRuleMap.put("/**", "jwt");
        // 访问401和404页面不通过我们的Filter
        filterRuleMap.put("/401", "anon");
        factoryBean.setFilterChainDefinitionMap(filterRuleMap);
        return factoryBean;
    }

    /**
     * 下面的代码是添加注解支持
     */
    @Bean
    @DependsOn("lifecycleBeanPostProcessor")
    public DefaultAdvisorAutoProxyCreator defaultAdvisorAutoProxyCreator() {
        DefaultAdvisorAutoProxyCreator defaultAdvisorAutoProxyCreator = new DefaultAdvisorAutoProxyCreator();
        // 强制使用cglib，防止重复代理和可能引起代理出错的问题
        // https://zhuanlan.zhihu.com/p/29161098
        defaultAdvisorAutoProxyCreator.setProxyTargetClass(true);
        return defaultAdvisorAutoProxyCreator;
    }

    @Bean
    public LifecycleBeanPostProcessor lifecycleBeanPostProcessor() {
        return new LifecycleBeanPostProcessor();
    }

    @Bean
    public AuthorizationAttributeSourceAdvisor authorizationAttributeSourceAdvisor(DefaultWebSecurityManager securityManager) {
        AuthorizationAttributeSourceAdvisor advisor = new AuthorizationAttributeSourceAdvisor();
        advisor.setSecurityManager(securityManager);
        return advisor;
    }
}