基于cookie的全局拦截器

包含加密解析和全局异常

首先判断用户的登录状态
获取cookie对象，解析用户ID的值，此操作包含加密解析和全局异常
如果用户ID不为空，并且在数据库中可以查找到记录，表示请求合法。
否则，请求不合法，进行拦截，重定向到登录界面

package com.qiangqiang.crm.interceptors;


import com.qiangqiang.crm.exceptions.NoLoginException;
import com.qiangqiang.crm.service.UserService;
import com.qiangqiang.crm.utils.LoginUserUtil;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;

import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class NoLoginInterceptor extends HandlerInterceptorAdapter {

    @Resource
    private UserService userService;
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        /**
         *  获取cookie 解析用户id
         *     如果用户id 存在 并且数据库中存在对应记录 请求合法   反之 用户未登录 请求非法
         */
        Integer userId= LoginUserUtil.releaseUserIdFromCookie(request);
        if(userId==0 || null== userService.selectByPrimaryKey(userId)){
            throw  new NoLoginException();
        }
        return super.preHandle(request, response, handler);
    }
}

package com.qiangqiang.crm.utils;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.lang3.StringUtils;

/**
 * Created by Tony on 2016/8/23.
 */
public class LoginUserUtil {

    /**
     * 从cookie中获取userId
     * @param request
     * @return
     */
    public static int releaseUserIdFromCookie(HttpServletRequest request) {
        String userIdString = CookieUtil.getCookieValue(request, "userIdStr");
        if (StringUtils.isBlank(userIdString)) {
            return 0;
        }
        Integer userId = UserIDBase64.decoderUserID(userIdString);
        return userId;
    }
}

package com.qiangqiang.crm.exceptions;

/**
 * 自定义参数异常
 */
public class NoLoginException extends RuntimeException {
    private Integer code=300;
    private String msg="用户未登录!";


    public NoLoginException() {
        super("用户未登录!");
    }

    public NoLoginException(String msg) {
        super(msg);
        this.msg = msg;
    }

    public NoLoginException(Integer code) {
        super("用户未登录!");
        this.code = code;
    }

    public NoLoginException(Integer code, String msg) {
        super(msg);
        this.code = code;
        this.msg = msg;
    }

    public Integer getCode() {
        return code;
    }

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

    public String getMsg() {
        return msg;
    }

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

package com.qiangqiang.crm.utils;

import org.apache.commons.lang3.StringUtils;

import java.util.Base64;


public class UserIDBase64 {

    /**
     * userID解密
     * @param encodedUserID 加密后的用户id
     * @return
     */
    public static Integer decoderUserID(String encodedUserID)  {
        if (StringUtils.isBlank(encodedUserID)) {
            return null;
        }
        try {
            String reversedString = new StringBuffer(encodedUserID).reverse().toString();
            String base64String = reversedString.replaceAll("#", "=");
            int userIDPos = base64String.indexOf("==") + 6;
            String realBase64UserID = base64String.substring(userIDPos);
            String base64Encoded = new String(Base64.getDecoder().decode(realBase64UserID.getBytes()));
            return Integer.parseInt(base64Encoded);
        } catch (Exception e) {
            return null;
        }
    }

    /**
     * 用户id加密
     * @param userID 用户id
     * @return
     */
    public static String encoderUserID(Integer userID){
        String base64UserIDEncoded = Base64.getEncoder().encodeToString((userID + "").getBytes());
        String currentStringBase64Encoded = Base64.getEncoder().encodeToString((System.currentTimeMillis() + "").getBytes());
        String keyString = currentStringBase64Encoded  
                + currentStringBase64Encoded.substring(4, 8) + base64UserIDEncoded;
        byte[] codeBytes = keyString.getBytes();
        byte[] ordedBytes = new byte[codeBytes.length];
        for(int i=0; i<codeBytes.length; i++){
            ordedBytes[i] = codeBytes[codeBytes.length-i-1];
        }
        return new String(ordedBytes).replaceAll("=", "#");
    }

    public static void main(String[] args) {
        System.out.println(encoderUserID(20));
        System.out.println(decoderUserID("#AjMzgjM##QN1AjN4gTOzgjM3UTM"));
    }
}