How to solve the problem of storing user tokens in Redis

Redis stores user token

When designing a system similar to e-commerce, a common requirement is that each page needs to carry logged-in user information.

There are two common solutions:

• Use cookies to save

• Use JWT to save

But if Redis cache is used in the system, then there is a third solution - cache the user token in Redis.

Generate a token when logging in and store it in Redis

//生成一个token对象,保存在redis中
redisTemplate.opsForHash().put("token","user",user);

When each page is generated, provide the token

//以JSON字符串形式返回token
@RequestMapping(value = "/getToken",method = RequestMethod.GET)
@ResponseBody
public User getToken(){
    User user = (User) redisTemplate.opsForHash().get("token", "user");
    return user;
}

//发送ajax请求，获取token
function get_token(){
    $.ajax({
        url:"getToken",
        type:"GET",
        dataType:"JSON",
        success:function(result){
            //将返回的用户信息保存在token中
            var token = result;
            //打印登录用户
            console.log(token);
            //打印登录用户的id
            console.log(token.id);
            document.getElementById('username').innerText = "用户名:"+token.username;
        }
    });
}

Delete the token when logging out

//注销
@RequestMapping("/logout")
public String logout(){
    redisTemplate.opsForHash().delete("token","user");
    return "/login";
}

Redis Dealing with token issues

java—Handling tokens based on redis

First of all, make it clear that token: token is a way of processing user information for front-end and back-end interaction after logging in. There are two main types Methods, one is based on session storage, and the other is based on redis storage. This article only discusses user information processing based on redis.   

For every information interaction after a user logs in, if user information needs to be passed, especially user IDs and the like, it is obviously unwise to query the database every time. We can Create a space in redis to save user information, and then we will use it from redis every time we need user information.

First create RedisUtil

@Component

public class RedisUtil {

    @Autowired
    private RedisTemplate redisTemplate;   //key-value是对象的

    //判断是否存在key
    public boolean hasKey(String key) {
        return redisTemplate.hasKey(key);
    }

    //从redis中获取值
    public Object get(String key) {
        return redisTemplate.opsForValue().get(key);
    }

    //向redis插入值
    public boolean set(final String key, Object value) {
        boolean result = false;
        try {
            redisTemplate.opsForValue().set(key, value);
            result = true;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }

    //向redis插入值带过期时间 单位:分钟
    public boolean set(final String key, Object value, long time) {
        boolean result = false;
        try {
            redisTemplate.opsForValue().set(key, value, time, TimeUnit.MINUTES);
            result = true;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }

    //redis删除值
    public boolean del(final String key) {
        return redisTemplate.delete(key);
    }

    //批量删除某个字段开始的key
    public long batchDel(String key) {
        Set<String> set = redisTemplate.keys(key + "*");
        return redisTemplate.delete(set);
    }

}

After creating RedisUtil, we need to store the value in redis. At this time, we need to pay attention to the fact that our key needs to be discussed with the front-end in advance, which field name to use, and the current-end When requesting, the key must be passed in the header. The value is encrypted and returned to the front end after the first login. After we get the header information, we need to decrypt the value first and use the value as the key to get the user information.

@Component
public class UserUtil {
    @Autowired
    private RedisUtil redisUtil;
    @Autowired
    private HttpServletRequest request;

    /**
     * 后台管理的登录id
     *
     * @return
     */
    public JsonResult getUser() {
        String header = request.getHeader("#与前端约定的统一字段#");
        //解密
        String decrypt = DESUtil.decrypt(header);
        if (!redisUtil.hasKey(decrypt))return JsonResult.error("未登录");
        User user = null;
        try {
            user = (User) redisUtil.get(decrypt);
        } catch (Exception e) {
            e.printStackTrace();
        }
        if (decrypt == null) return JsonResult.error("权限不足");
        return JsonResult.success(user);
    }
}

When we need it

        JsonResult jsonResult = userUtil.getUser();
        if (jsonResult.getCode() != 1) return jsonResult;
        //强转成对象。此处不用担心强转失败，因为存入的时候就是对象存储，只不过为了复用，存的是object类型
        User user= (User) jsonResult.getData();
        return JsonResult.success(#service层#);
    }

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