=============
后端_登录拦截
=============

前端-请求->拦截器-请求->控制器->...
             |
        判断是否登录
        是|      |否
        放行    拒绝

1 创建登录拦截器

/ysdblog-api/src/main/java/com/weihome/ysdblog/handler/LoginInterceptor.java：

@Slf4j
@Component
public class LoginInterceptor implements HandlerInterceptor {
    @Autowired
    LoginService loginService;
    /**
     * 前置拦截处理
     * 在执行控制器方法之前执行
     * 登录验证
     */
    @Override
    public boolean preHandle(
        HttpServletRequest request, HttpServletResponse response,
        Object handler) throws Exception {
        // 若所要访问的不是控制器方法，如静态资源(RequestResourceHandler)等
        if (!(handler instanceof HandlerMethod))
            return true; // 无需验证，直接放行

        // 从请求头中获取令牌
        String token = request.getHeader("Authorization");
        log.info("---------------- REQUEST ----------------");
        log.info("Request URI: {}", request.getRequestURI());
        log.info("Request Method: {}", request.getMethod());
        log.info("Token: {}", token);
        log.info("-----------------------------------------");

        // 若请求头中没有令牌，即尚未登录
        if (StringUtils.isBlank(token)) {
            Result result = Result.fail(
                ErrorCode.NO_LOGIN.getCode(),
                ErrorCode.NO_LOGIN.getMsg());
            response.setContentType("application/json;charset=utf-8");
            response.getWriter().print(JSON.toJSONString(result));
            return false; // 验证失败，拒绝访问
        }

        // 若根据令牌找不到用户，即令牌有误
        User user = loginService.findUserByToken(token);
        if (user == null) {
            Result result = Result.fail(
                ErrorCode.TOKEN_ERROR.getCode(),
                ErrorCode.TOKEN_ERROR.getMsg());
            response.setContentType("application/json;charset=utf-8");
            response.getWriter().print(JSON.toJSONString(result));
            return false; // 验证失败，拒绝访问
        }

        return true; // 验证通过，允许访问
    }
}

2 启用登录拦截器

/ysdblog-api/src/main/java/com/weihome/ysdblog/config/WebMvcConfig.java：

...
public class WebMvcConfig implements WebMvcConfigurer {
    ...
    @Autowired
    private LoginInterceptor loginInterceptor;
    ...
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(loginInterceptor)
            .addPathPatterns("/test");
    }
    ...
}

3 测试控制器

/ysdblog-api/src/main/java/com/weihome/ysdblog/controller/TestController.java：

@RestController
@RequestMapping("test")
public class TestController {
    @RequestMapping
    public Result test() {
        return Result.success(null);
    }
}

4 运行测试

Postman
    GET
        localhost:8888/test
    Headers
        没有Authorization
---------------------------
{
    "code": 90002,
    "msg": "未登录",
    "success": false
}

后端日志：

---------------- REQUEST ----------------
Request URI: /test
Request Method: POST
Token: null
-----------------------------------------

Postman
    GET
        localhost:8888/test
    Headers
        Authorization: abcd
---------------------------
{
    "code": 10003,
    "msg": "令牌有误",
    "success": false
}

后端日志：

---------------- REQUEST ----------------
Request URI: /test
Request Method: GET
Token: abcd
-----------------------------------------

Postman
    GET
        localhost:8888/test
    Headers
        Authorization: eyJhbGciOiJIUzI1NiJ9.eyJleHAiOjE2NDk1ODQyMjcsInVzZXJJZCI6MTUwOTM2MzE2Mjc2MjE4Njc1NCwiaWF0IjoxNjQ4Njk1MTk1fQ.cHFM0rmfQvr6frtWJaC1citGTESGt0b25FOBNwPgdlY
---------------------------
{
    "success": true,
    "code": 200,
    "msg": "success",
    "data": null
}

后端日志：

---------------- REQUEST ----------------
Request URI: /test
Request Method: GET
Token: eyJhbGciOiJIUzI1NiJ9.eyJleHAiOjE2NDk1ODQyMjcsInVzZXJJZCI6MTUwOTM2MzE2Mjc2MjE4Njc1NCwiaWF0IjoxNjQ4Njk1MTk1fQ.cHFM0rmfQvr6frtWJaC1citGTESGt0b25FOBNwPgdlY
-----------------------------------------