前后端分离基于jwt的用户认证实现_checktokeninterceptor

• 所需依赖java-jwt与jjwt

        <dependency>
            <groupId>com.auth0</groupId>
            <artifactId>java-jwt</artifactId>
            <version>3.15.0</version>
        </dependency>
        <dependency>
            <groupId>io.jsonwebtoken</groupId>
            <artifactId>jjwt</artifactId>
            <version>0.9.1</version>
        </dependency>
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• 在登录接口的业务层生成token

 JwtBuilder builder = Jwts.builder();
 HashMap<String, Object> map = new HashMap<>();
 map.put("key1","value1");//可以使用map存储用户角色权限信息
 String token = builder.setSubject(username)
        .setIssuedAt(new Date())//设置token的生成时间
        .setId(users.getUserId() + "")//设置用户id为token的id
        .setClaims(map)//map中可以存放用户的角色权限信息
        .setExpiration(new Date(System.currentTimeMillis() + 24 * 60 * 60 * 1000))//设置token的过期使时间
        .signWith(SignatureAlgorithm.HS256, "yongxin")//设置加密方式和加密密码
        .compact();
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• 前端登录页面拿到token并将其存储在cookie中

	//如果登录成功，把token存储到cookie中
	setCookieValue("token",res.data.msg);
	//这里把cookie的操作封装在一个js文件中
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• 前端访问受限页面时间向后端请求在headers中携带token

前端但凡访问受限资源，都必须携带token发送请求，token可以通过请求行(params)，请求头(header)以及请求体(data)传递，但是习惯性使用请求头(header)传递

				created:function(){
					this.token = getCookieValue("token");
					axios({
						method:"get",
						url:baseUrl+"/shoppingCart/list",
						headers:{
							token:this.token
						}
					}).then(function(res){
						//判断是否合法，合法则渲染页面
					})
				}
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• 后端在拦截器中验证前端请求携带的token

注意：当前端发送的请求携带自定义请求头时，浏览器的预检机制会发送一次预检请求(mehtod=“options”)，后端响应预检请求，之后前端才会发送真正携带数据的请求。因此我们要在拦截器中加以判断。

@Component
public class CheckTokenInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //放行预检请求
        String method = request.getMethod();
        if ("OPTIONS".equalsIgnoreCase(method)){
            return true;
        }
        String token = request.getHeader("token");
        if (token ==null){
            ResultVO resultVO = new ResultVO(1001, "请先登录", null);
            doResponse(response,resultVO);
        }else {
            //验证token
            JwtParser parser = Jwts.parser();
            parser.setSigningKey("yongxin");//解析token的SigningKey必须与生成token的密码一致
            try {
                Jws<Claims> claimsJws = parser.parseClaimsJws(token);
                Claims body = claimsJws.getBody();//获取token中的用户数据
                String subject = body.getSubject();
                String v1 = body.get("key1", String.class);
                ResultVO resultVO = new ResultVO(1000, "success", null);
                doResponse(response,resultVO);
            } catch (UnsupportedJwtException e){
                ResultVO resultVO = new ResultVO(1001, "登录过期，请重新登录！", null);
                doResponse(response,resultVO);
            } catch (ExpiredJwtException e){
                ResultVO resultVO = new ResultVO(1001, "token不合法，请自重！", null);
                doResponse(response,resultVO);
            } catch (Exception e){
                ResultVO resultVO = new ResultVO(1001, "请重新登录！", null);
                doResponse(response,resultVO);
            }
        }
        return false;
    }
    private void doResponse(HttpServletResponse response, ResultVO resultVO) throws IOException {
        response.setContentType("application/json");
        response.setCharacterEncoding("UTF-8");
        PrintWriter writer = response.getWriter();
        String s = new ObjectMapper().writeValueAsString(resultVO);
        writer.println(s);
        writer.flush();
        writer.close();

    }
}
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注册拦截器

@Configuration
public class InterceptorConfig implements WebMvcConfigurer {
    @Autowired
    private CheckTokenInterceptor checkTokenInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(checkTokenInterceptor)
                .addPathPatterns("/shoppingCart/**");//需要拦截的受限资源请求
                /*.excludePathPatterns("/users/**");*/
    }
}
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