@Service
public class UserDetailsServiceImpl implements UserDetailsService {
    @Autowired
    private UserMapper userMapper;
    //loadUserByUsername方法即為流程圖中查詢用戶信息的方法。
    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
        //查詢用戶信息
        LambdaQueryWrapper<User> queryWrapper= new LambdaQueryWrapper<>();
        queryWrapper.eq(User::getUserName,username);
        User user = userMapper.selectOne(queryWrapper);
        //如果沒有查詢到用戶
        if(Objects.isNull(user)){
            throw new RuntimeException("用戶名或密碼錯(cuò)誤");
        }
        //封裝為UserDetails類型返回
        return new LoginUser(user);
    }
}

@RestController
public class LoginController {
    @Autowired
    private LoginService loginService;
    @PostMapping("/user/login")
    public ResponseResult login(@RequestBody User user){
        //登陸
        return loginService.login(user);
    }

@Configuration
public class SecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    @Bean //(name = "") //獲取AuthenticationManager的bean，因?yàn)楝F(xiàn)在只有這一個(gè)AuthenticationManager，所以不寫也沒事。
    protected AuthenticationManager authenticationManager() throws Exception {
        return super.authenticationManager();
    }
    //放開接口
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
                //關(guān)閉csrf,csrf為跨域策略，不支持post
                .csrf().disable()
                //不通過session獲取SecurityContext 前后端分離時(shí)session不可用
                .sessionManagement().sessionCreationPolicy(SessionCreationPolicy.STATELESS)
                .and()
                .authorizeRequests()
                //對(duì)于登陸接口，允許匿名訪問,登陸之后不允許訪問,只允許匿名的用戶,可以防止重復(fù)登陸。
                .antMatchers("/user/login").anonymous() //permitAll() 登錄能訪問,不登錄也能訪問,一般用于靜態(tài)資源js等
                //除了上面外，所有請(qǐng)求需要鑒權(quán)認(rèn)證
                .anyRequest().authenticated();//authenticated():任意用戶，認(rèn)證后都可訪問。
    }
}

@Service
public class LoginServiceImpl implements LoginService {
    @Autowired
    private AuthenticationManager authenticationManager;
    @Autowired
    private RedisCache redisCache;
    //登陸
    @Override
    public ResponseResult login(User user) {
        //獲取AuthenticationManager的authenticate方法進(jìn)行認(rèn)證。
        //通過SecurityConfig獲取AuthenticationManager
        //創(chuàng)建Authentication,第一個(gè)參數(shù)為認(rèn)證主體，沒有的話傳用戶名,第二個(gè)參數(shù)傳密碼
        UsernamePasswordAuthenticationToken authenticationToken
                =new UsernamePasswordAuthenticationToken(user.getUserName(),user.getPassword());
        //需要Authentication參數(shù)(上面)
        Authentication authenticate = authenticationManager.authenticate(authenticationToken);
        //這樣讓ProviderManager調(diào)用UserDetailsService類中的loadUserByUsername方法完成認(rèn)證
        //如果認(rèn)證不通過，authenticate為null
        //認(rèn)證沒通過，給出提示
        if(Objects.isNull(authenticate)){
            throw new RuntimeException("登陸失敗");
        }
        //認(rèn)證通過，使用userid生成jwt,jwt存入ResponseResult返回
          //獲取userId
        LoginUser loginUser = (LoginUser) authenticate.getPrincipal();
        String userId = loginUser.getUser().getId().toString();
        String jwt = JwtUtil.createJWT(userId);
        Map<String,String> map = new HashMap<>();
        map.put("token",jwt);
        //完整信息存入redis，userid作key
        redisCache.setCacheObject("login:"+userId,loginUser);
        return new ResponseResult(200,"登陸成功",map);
    }
}

public class JwtUtil {
    //有效期為
    public static final Long JWT_TTL = 60*60*1000L;//一個(gè)小時(shí)
    //設(shè)置密鑰明文 。隨便定義，方便記憶和使用即可，但需要長(zhǎng)度要為4的倍數(shù)。
    public static final String JWT_KEY = "jyue";
    public static String getUUID(){
        String token = UUID.randomUUID().toString().replaceAll("-", "");
        return token;
    }
    //生成JWT
    //subject為token中存放的數(shù)據(jù)（json格式）
    public static String createJWT(String subject){
        JwtBuilder builder = getJwtBuilder(subject, null, getUUID());//設(shè)置過期時(shí)間
        return builder.compact();
    }
    public static JwtBuilder getJwtBuilder(String subject,Long ttlMillis,String uuid){
        SignatureAlgorithm signatureAlgorithm = SignatureAlgorithm.HS256;
        SecretKey secretKey=generalKey();
        long nowMillis = System.currentTimeMillis();
        Date now = new Date(nowMillis);
        if(ttlMillis ==null){
            ttlMillis=JwtUtil.JWT_TTL;
        }
        long expMills=nowMillis+ttlMillis;
        Date expDate = new Date(expMills);
        return Jwts.builder()
                .setId(uuid) //唯一id
                .setSubject(subject) //主題 可以是JSON數(shù)據(jù)
                .setIssuer("jy") //簽發(fā)者,隨便寫
                .setIssuedAt(now) //簽發(fā)時(shí)間
                .signWith(signatureAlgorithm,secretKey) //使用HS256對(duì)稱加密算法簽名，第二個(gè)參數(shù)為密鑰。
                .setExpiration(expDate);
    }
    public static SecretKey generalKey(){
        byte[] encodeKey = Base64.getDecoder().decode(JwtUtil.JWT_KEY);
        SecretKeySpec key = new SecretKeySpec(encodeKey, 0, encodeKey.length, "AES");
        return key;
    }
    public static Claims parseJWT(String jwt)throws Exception{
        SecretKey secretKey = generalKey();
        return Jwts.parser()
                .setSigningKey(secretKey)
                .parseClaimsJws(jwt)
                .getBody();
    }
}

@SuppressWarnings(value = {"unchecked","rawtypes"})
@Component
public class RedisCache {
    @Autowired
    public RedisTemplate redisTemplate;
    //緩存對(duì)象
    //key 緩存鍵值
    //value 緩存值
    public <T> void setCacheObject(final String key,final T value){
        redisTemplate.opsForValue().set(key,value);
    }
    //獲取緩存的基本對(duì)象
    // key 鍵值
    // return 緩存鍵對(duì)應(yīng)的數(shù)據(jù)
    public <T>T getCacheObject(final String key){
        ValueOperations<String,T> operation = redisTemplate.opsForValue();
        return operation.get(key);
    }
}

@Component            //繼承這個(gè)實(shí)現(xiàn)類，保證了請(qǐng)求只會(huì)經(jīng)過該過濾器一次
public class JwtAuthenticationTokenFilter extends OncePerRequestFilter {
    @Autowired
    private RedisCache redisCache;
    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
        //首先需要從請(qǐng)求頭中獲取token
        String token = request.getHeader("token");
        //判斷token是否為Null
        if(!StringUtils.hasText(token)) {
            //token沒有的話，直接放行，拋異常的活交給后續(xù)專門的過濾器。
            filterChain.doFilter(request, response);
            //響應(yīng)時(shí)還會(huì)經(jīng)過該過濾器一次，直接return，不能執(zhí)行下面的解析token的代碼。
            return;
        }
        //如何不為空，解析token，獲得了UserId
        String userId;
        try {
            Claims claims = JwtUtil.parseJWT(token);
            userId = claims.getSubject();
        } catch (Exception e) {
            e.printStackTrace();
            //token格式異常，不是正經(jīng)token
            throw new RuntimeException("token非法");
        }
        //根據(jù)UserId查redis獲取用戶數(shù)據(jù)
        String key = "login:"+userId;
        LoginUser loginUser = redisCache.getCacheObject(key);
        if(Objects.isNull(loginUser)){
            throw new RuntimeException("用戶未登錄");
        }
        //然后封裝Authentication對(duì)象存入SecurityContextHolder
        // 因?yàn)楹罄m(xù)的過濾器會(huì)從SecurityContextHolder中獲取信息判斷認(rèn)證情況，而決定是否放行。
        // 這里用UsernamePasswordAuthenticationToken三個(gè)參數(shù)的構(gòu)造函數(shù)，是因?yàn)槠淠茉O(shè)置已認(rèn)證的狀態(tài)(因?yàn)橐呀?jīng)從redis中獲取了信息，確認(rèn)是認(rèn)證的了)
        //第一個(gè)參數(shù)為用戶信息，第三個(gè)參數(shù)為權(quán)限信息，目前還沒獲取，先填null
        UsernamePasswordAuthenticationToken authenticationToken = new UsernamePasswordAuthenticationToken(loginUser,null,null);
        //默認(rèn)SecurityContextHolder是ThreadLocal線程私有的，這也是為什么上面要用UsernamePasswordAuthenticationToken三個(gè)參數(shù)的構(gòu)造方法
        SecurityContextHolder.getContext().setAuthentication(authenticationToken);
        filterChain.doFilter(request,response);
    }
}