使用HandlerInterceptor 中注入其他service时为null分析及解决

雨点打透心脏的1/2处 2023-10-15 22:27 10阅读 0赞

### 一情况分析 ###

#### 1.1 拦截器代码 ####

public class ServerInterceptor implements HandlerInterceptor {
        
        private static final Logger _logger = LoggerFactory.getLogger(ServerInterceptor.class);
        PrintWriter out;
        JSONObject res = new JSONObject();
        
        @Autowired
        UserInfoLoginService userInfoLoginService;
        @Autowired
        SysUserService sysUserService;
        
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        
    
            response.setCharacterEncoding("UTF-8");
            response.setContentType("application/json; charset=utf-8");
            _logger.info("ServerInterceptor逻辑处理");
            String header = request.getHeader("Server");
            if (!"Server".equals(header)) {
        
                _logger.info("ServerInterceptor无权限");
                res.put("code", "Server");
                res.put("msg", "ServerInterceptor无权限");
                res.put("data", null);
                out = response.getWriter();
                out.append(res.toString());
                return false;
            }
            return true;
        }

#### 1.2 拦截器配置 ####

![在这里插入图片描述][0e89c1c5832647b3bfda83733207af70.png]

#### 1.3 原因 ####

造成 UserInfoLoginService，SysUserService 为null的原因：  
拦截器加载是在springcontext创建之前完成的，在拦截器配置进行加载，进行new ServerInterceptor（）时，这里只是创建的ServerInterceptor空对象，并没有将内部属性进行注入；容器启动结束在使用拦截器时注入实体自然就为null。

### 二解决方案 ###

在拦截器配置中将拦截器提前暴露，交给spring容器管理

@Configuration
    public class InterceptorConfig implements WebMvcConfigurer {
        
        @Resource
        InterceptorProperties interceptorProperties;
    
        @Resource
        ServerInterceptor serverInterceptor;
    
    
        @Override
        public void addInterceptors(InterceptorRegistry registry) {
        
    
    
            //注册ServerInterceptor
            InterceptorRegistration serverRegistration = registry.addInterceptor(serverInterceptor);
    
            if (!CollectionUtils.isEmpty(interceptorProperties.getIncludeFilterServerPaths())) {
        
                // Server拦截路径
               serverRegistration.addPathPatterns(interceptorProperties.getIncludeFilterServerPaths());
            }
           
    
    
        }
    }

2、拦截器添加@Component，交给容器管理

@Component
    public class ServerInterceptor implements HandlerInterceptor {
        
        private static final Logger _logger = LoggerFactory.getLogger(ServerInterceptor.class);
        PrintWriter out;
        JSONObject res = new JSONObject();
    
        @Autowired
        UserInfoLoginService userInfoLoginService;
    
        @Autowired
        SysUserService sysUserService;
    
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        
    
            response.setCharacterEncoding("UTF-8");
            response.setContentType("application/json; charset=utf-8");
            _logger.info("ServerInterceptor逻辑处理");
            String header = request.getHeader("Server");
            if (!"Server".equals(header)) {
        
                _logger.info("ServerInterceptor无权限");
                res.put("code", "Server");
                res.put("msg", "ServerInterceptor无权限");
                res.put("data", null);
                out = response.getWriter();
                out.append(res.toString());
                return false;
            }
            return true;
        }
    
    }

[0e89c1c5832647b3bfda83733207af70.png]: https://img-blog.csdnimg.cn/0e89c1c5832647b3bfda83733207af70.png