自定义拦截器和注解

在实际项目中有时需要用到自定义注解方便业务的实现，比如说日志，在实现自定义注解时一般和拦截器一起结合，通过拦截器实现注解的业务，也可用aop实现，具体如下

先顶一个控制层，其中@VerifyToken就是我们要实现的自定义注解

@RestController
@RequestMapping("/user")
public class UserController {
    
    /**
    *@VerifyToken就是我们要实现的自定义注解
    /
    @VerifyToken // 加上注解表示需要该方法需要验证token
    @GetMapping("/getUser")
    public Result getUser(String id){
        User u = userService.findUserById(id);
        return new Result("1001","成功",u);
    }
}

定义一个自定义注解接口类，还可以往注解类中添加其他属性

@Target({ElementType.METHOD,ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface VerifyToken {
    boolean required() default true;
}

编写拦截器，preHandle方法为主要方法

@Component
public class AuthInterceptor implements HandlerInterceptor {
    @Autowired
    private UserService userService;

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        Map params = new HashMap<>();
        Enumeration paramNames = request.getParameterNames();
        while (paramNames.hasMoreElements()) {
            String paramName = (String) paramNames.nextElement();
            String[] paramValues = request.getParameterValues(paramName);
            if (paramValues.length == 1) {
                if (paramValues[0].length() != 0) {
                    params.put(paramName, paramValues[0]);
                }
            }
        }
        HandlerMethod hander = (HandlerMethod) handler;
        System.out.println("请求类："+hander.getClass()+"；请求方法："+((HandlerMethod) handler).getMethod().getName()+";请求参数："+ JSONUtils.toJSonString(params));
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("222222222222222222222");
    }
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object object) throws Exception{
        boolean bo = false;
        // 获取token
        String token = request.getHeader("token");
        // 如果不是映射到Controller直接放行
        if(!(object instanceof HandlerMethod)){
            bo = true;
        }
        // 检查是否需要验证token
        HandlerMethod handlerMethod = (HandlerMethod)object;
        Method method = handlerMethod.getMethod();
        if(method.isAnnotationPresent(VerifyToken.class)){
            String str = checkToken(method,token);
            if(!StringUtils.isEmpty(str)) throw new RuntimeException(str);
            else bo = true;
        }else bo = true;
        return bo;
    }
    public String checkToken(Method method,String token){
        VerifyToken loginToken = method.getAnnotation(VerifyToken.class);
        if(loginToken.required()){
            if(null == token){
                return "该请求没有token，请先获取token";
            }
            if(TokenUtil.verifyToken(token)){// 有效，判断是否要刷新令牌
                return null;
            }else{
                return "无效令牌";
            }
        }
        return null;
    }


}

将拦截器注册到spring中管理，这样就完成了

@Component
public class InterceptorConfig implements WebMvcConfigurer {
    @Autowired
    private AuthInterceptor authInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        System.out.println("=================请求已拦截");
        // 拦截所有请求
        registry.addInterceptor(authInterceptor).addPathPatterns("/**");
    }

}