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
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
@Component public class ProjectInterceptor2 implements HandlerInterceptor { @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { System.out.println("preHandle...222"); return true; } @Override public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { System.out.println("postHandle...222"); } @Override public 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 { @Autowired private ProjectInterceptor projectInterceptor; @Autowired private ProjectInterceptor2 projectInterceptor2; @Override public 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
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
