项目的登入登出

1、登陆登出的逻辑：
在用户登陆时随机生成一个TOKEN的字符串，将该字符串存放到redis中，键为随机生成的字符串，本项目中为一个固定前缀加一个UUID随机生成的字符串，
值为用于唯一标识，本项目中为用户的openid，并设置过期时间；然后在后台生成一个Cookie，将key作为Cookie的值，“token”为键存在Cookie中，设置过期时间，并将Cookie通过HttpServletResponse
返回给前台用户浏览器。

在用户登出时，从HttpServletRequest中Cookie中取出key为“token”的Cookie，从该Cookie中取出value即存在redis中用户唯一标识的键，并从Redis从删除该值，并将该Cookie也删除，从而完成用户登出。

2、实现

（1）、首先是redis的使用：
引入依赖：
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-redis</artifactId>
        <version>1.4.4.RELEASE</version>
    </dependency>

（2）、Conrtroller：
@Controller
@RequestMapping("/seller")
public class SellerInfoController {

    @Autowired
    private SellerInfoService sellerInfoService;
    //注入stringRedisTemplate操作Redis
    @Autowired
    private StringRedisTemplate stringRedisTemplate;
    //注入项目配置常量
    @Autowired
    private ProjectConfig projectConfig;


    @GetMapping("/login")
    public ModelAndView login(@RequestParam("openid")String openid,
                              HttpServletResponse response,
                              Map<String,Object> map) {
        SellerInfo sellerInfo  = sellerInfoService.findSellerByOpenid(openid);
        if (sellerInfo==null) {
            map.put("msg", ResultEums.LOGIN_FAIL.getMessage());
            map.put("url","/sell/seller/order/list");
            return new ModelAndView("/common/error",map);
        }
        //设置token至redis
        Integer expire = RedisConstant.EXPIRE;
        String token = UUID.randomUUID().toString();
        stringRedisTemplate.opsForValue().set(String.format(RedisConstant.TOKEN_PREFIX,token),openid,expire,TimeUnit.SECONDS);
        //设置token至cookie
        CookieUtil.set(response,"token",CookieConstrant.TOKEN,expire);
        return new ModelAndView("redirect:"+projectConfig.getSell()+"/sell/seller/order/list");
    }

    public ModelAndView logout(HttpServletRequest request,
                               HttpServletResponse response,
                               Map<String,Object> map) {
        //从cookie中得到token
        Cookie cookie = CookieUtil.get(request,CookieConstrant.TOKEN);
        if (cookie!=null) {
            stringRedisTemplate.opsForValue().getOperations().delete(String.format(RedisConstant.TOKEN_PREFIX,cookie.getValue()));
        }
        //清楚cookie
        CookieUtil.set(response,CookieConstrant.TOKEN,null,0);
        map.put("msg",ResultEums.LOGOUT_OUT_SUCCESS.getMessage());
        map.put("url","/sell/seller/order/list");
        return new ModelAndView("/common/",map);

    }

    其中CookieUtil：
    public class CookieUtil {

        public static void set(HttpServletResponse response,String key,String value,int maxAge) {
            Cookie cookie = new Cookie("token", CookieConstrant.TOKEN);
            cookie.setMaxAge(maxAge);
            cookie.setPath("/");
            response.addCookie(cookie);
        }

        public static Cookie get(HttpServletRequest request,String name) {
            Map<String,Cookie> cookieMap = readCookieMap(request);
            if (cookieMap.containsKey(name)) {
                return cookieMap.get(name);
            }else {
                return null;
            }
        }

        private static Map<String,Cookie> readCookieMap(HttpServletRequest request) {
            Map<String,Cookie> cookieMap = new HashMap<>();
            Cookie[] cookies = request.getCookies();
            if (cookies!=null){
                for (Cookie cookie:cookies
                     ) {
                    cookieMap.put(cookie.getName(),cookie);
                }
            }
            return cookieMap;
        }
    }

    SellerInfoService:
    @Slf4j
    @Service
    public class SellerInfoServiceImpl implements SellerInfoService {
        @Autowired
        private SellerInfoRepository sellerInfoService;

        @Override
        public SellerInfo findSellerByUsername(String username) {
           SellerInfo sellerInfo = sellerInfoService.findByUsername(username);

            return sellerInfo;
        }

        @Override
        public SellerInfo findSellerByOpenid(String openid) {
            SellerInfo sellerInfo = sellerInfoService.findByOpenid(openid);
            return sellerInfo;
        }
    }


    其中几个配置常量：
    public interface CookieConstrant {
        String TOKEN="token";
        Integer EXPIRE=7200;
    }

    public interface RedisConstant {

     String TOKEN_PREFIX="token_%s";
        Integer EXPIRE=7200;
    }



    3、关于redis的使用：
    stringRedisTemplate.opsForValue().set(String.format(RedisConstant.TOKEN_PREFIX,token),openid,expire,TimeUnit.SECONDS);

    stringRedisTemplate.opsForValue().getOperations().delete(String.format(RedisConstant.TOKEN_PREFIX,cookie.getValue()));