执行位置在请求到达DispacherServlet后，在DispacherServlet上调用Controller类来执行
拦截器用途：
判断用户是否登录
监听生成的日志信息
拦截器的实现
publicclassmyinterceptorimplementshandlerinterceptor { @ overridepublicvoidaftercompletion (httpservletrequestrequest，http STP 对象手， exception ex (throws exception { } @ overridepublicvoidposthandle (httpservletreesponse ) ) overridepublicvoidposthandle 652 htle Object handler，modelandview modelandview (throws exception { } @ overridepublicbooleanprehandle (httpservletrequestrequest， httpservletrespoort object handler (throws exception (/return false阻止继续调用return true )； 实现HandlerInterceptor中各方法的执行顺序和关系
拦截器的配置
MVC :映射路径=" "需要过滤的路径
MVC :排除路径=' '排除路径
bean class=“实现handler interceptor类的全名”进行此过滤的类
MVC : interceptors MVC : interceptor MVC : mapping path='/* '/MVC : exclude-mapping path='/log in/* '/beancc