版权声明:望支持~~~ https://blog.csdn.net/u011663149/article/details/87169171
前言:
公司小伙伴反馈由于业务需要,需要在拦截器、过滤器中操作Redis,按照 Controller,Service层配置发现无法注入,一直报(Nullpoint)空指针异常。
原因:
拦截器、过滤器执行在Bean初始化之前导致这个问题的。在web.xml中各个元素的执行顺序是这样的,context-param-->listener-->filter-->servlet; 如果从整个项目中看,一个servlet请求的执行过程就变成了这样context-param-->listener-->filter-->servlet-->interceptor,拦截器、过滤器是在servlet执行之后,因为其本身就是在servlet内部的。
解决办法:
项目基于SpringBoot
/**
* @author DHing
*/
public class AppConfig implements WebMvcConfigurer {
/*将自定义拦截器、过滤器作为Bean写入配置*/
@Bean
TestInterceptor testInterceptor() {
return new TestInterceptor();
}
/**
* 对拦截器注册
*/
@Override
public void addInterceptors(InterceptorRegistry registry) {
//注册日志拦截器
registry.addInterceptor(testInterceptor())
//添加需要拦截的路径
.addPathPatterns("/**")
.excludePathPatterns("/swagger-resources/**", "/webjars/**", "/v2/**", "/swagger-ui.html/**", "/doc.html/**");
}
}
/**
* @author DHing
*/
@Slf4j
public class TestInterceptor implements HandlerInterceptor {
@Autowired
private Redisson redission;
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response,
Object handler) throws Exception {
log.info("from redis : {}" , redission.getBucket("KEY"));
return true;
}
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
ModelAndView modelAndView) throws Exception {
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response,
Object handler, Exception ex) throws Exception {
}
}