Spring MVC 拦截器

拦截器的执行流程图

代码清单

在Spring MVC的配置文件中配置拦截器(这里配置了两个拦截器)

<!-- 配置拦截器 --> <mvc:interceptors> <mvc:interceptor> <!-- 配置要拦截的请求 --> <mvc:mapping path="/*"/> <!-- 配置自定义的拦截器 --> <bean class="com.zgz.springmvc.interceptors.FirstInterceptor"></bean> </mvc:interceptor> <mvc:interceptor> <!-- 配置多个拦截器 --> <mvc:mapping path="/*"/> <bean class="com.zgz.springmvc.interceptors.SecondInterceptor"></bean> </mvc:interceptor> </mvc:interceptors>

拦截器必须实现HandlerInterceptor接口，该接口定义了三个方法，掌握这三个方法的作用和有多个拦截器时的执行过程即可
多个拦截器时的执行流程图

两个拦截器

public class FirstInterceptor implements HandlerInterceptor { /** * 该方法在目标方法之前调用 * 若该方法返回值为true，则继续调用后续的拦截器和目标方法 * 若返回值为false，则不会调用后续的拦截器和目标方法 * * 可以考虑做权限，日志，事务等 * @return * @throws Exception */ @Override public boolean preHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2) throws Exception { System.out.println("preHandle: "); return true; } /** * 调用目标方法之后，但在渲染视图之前 * 可以对请求域中的属性或视图做出修改 * @throws Exception */ @Override public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, ModelAndView arg3) throws Exception { System.out.println("postHandle: "); } /*** * 渲染试图之后被调用 * 可以释放资源 * @throws Exception */ @Override public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, Exception arg3) throws Exception { System.out.println("afterCompletion: "); }}

public class SecondInterceptor implements HandlerInterceptor { @Override public boolean preHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2) throws Exception { System.out.println("preHandle2: "); return true; } @Override public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, ModelAndView arg3) throws Exception { System.out.println("postHandle2: "); } @Override public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, Exception arg3) throws Exception { System.out.println("afterCompletion2: "); }}

执行结果