详解SpringMVC的拦截器参数及拦截器链配置详解SpringMVC的拦截器参数及拦

一、拦截器参数
二、拦截器链配置

一、拦截器参数前置处理

public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.out.println("preHandle..."); return true; }

参数：
■ request：请求对象
■ response：响应对象
■ handler：被调用的处理器对象，本质上是一个方法对象，对反射技术中的Method对象进行再包装
返回值：
■ 返回值为false，被拦截的处理器将不执行
【详解SpringMVC的拦截器参数及拦截器链配置】后置处理

public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println("postHandle..."); }

参数：
modeAanView：如果处理器执行完成具有返回结果，可以读取到对应数据与页面信息，并进行调整
完成后处理

public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println("afterCompletion..."); }

参数：
ex：如果处理器执行过程中出现异常对象，可以针对异常情况进行单独处理

二、拦截器链配置配置第一个拦截器

@Component//定义拦截器类，实现HandlerInterceptor接口//注意当前类必须受Spring容器控制public class ProjectInterceptor implements HandlerInterceptor {@Override//原始方法调用前执行的内容//返回值类型可以拦截控制的执行，true放行，false终止public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {String contentType = request.getHeader("Content-Type"); HandlerMethod hm = (HandlerMethod)handler; System.out.println("preHandle..."+contentType); return true; } @Override//原始方法调用后执行的内容public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println("postHandle..."); } @Override//原始方法调用完成后执行的内容public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println("afterCompletion..."); }}

配置第二个拦截器

@Componentpublic class ProjectInterceptor2 implements HandlerInterceptor {@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.out.println("preHandle...222"); return true; } @Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println("postHandle...222"); } @Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println("afterCompletion...222"); }}

当配置多个拦截器时，形成拦截器链

@Configuration@ComponentScan({"com.itheima.controller"})@EnableWebMvc//实现WebMvcConfigurer接口可以简化开发，但具有一定的侵入性public class SpringMvcConfig implements WebMvcConfigurer {@Autowiredprivate ProjectInterceptor projectInterceptor; @Autowiredprivate ProjectInterceptor2 projectInterceptor2; @Overridepublic void addInterceptors(InterceptorRegistry registry) {//配置多拦截器registry.addInterceptor(projectInterceptor).addPathPatterns("/books","/books/*"); registry.addInterceptor(projectInterceptor2).addPathPatterns("/books","/books/*"); }}

三个拦截器构成的拦截器链图例

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拦截器链的运行规律参照拦截器添加顺序为准
当拦截器中出现对原始处理器的拦截，后面的拦截器均终止运行
当拦截器运行中断，仅运行配置在前面的拦截器的afterCompletion操作
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