介绍
拦截器一般用在某个方法被访问之前进行拦截,然后在方法执行之前或之后加入某些操作。
使用
1、创建一个SpringBoot工程,定义一个自定义拦截器类,实现HandlerInterceptor接口,重写三个方法。
public class MyInterceptor implements HandlerInterceptor {
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
System.out.println("preHandle.....");
//简单实现对是否登录的判断
User user = (User) request.getSession().getAttribute("loginUser");
if(user != null){
return true;
}
return false;
}
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
System.out.println("postHandle......");
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
System.out.println("afterCompetion......");
}
}
方法分析
preHandle()在请求方法之前执行,返回值为boolean类型,true表示请求继续执行,false表示请求结束。
postHandle()在请求处理完成,dispatcherServlet返回视图后执行。
afterCompletion()在dispatcherServlet渲染视图后执行。
2、编写拦截器配置类
@Configuration
public class WebMvcConfig extends WebMvcConfigurerAdapter {
@Override
public void addInterceptors(InterceptorRegistry registry) {
//拦截所有请求
String[] addPathPatterns = {"/**"};
//不需要拦截的请求
String[] excludePathPatterns = {"/page/logout","/page/login","/page/init","/reader/login"};
registry.addInterceptor(new MyInterceptor()).addPathPatterns(addPathPatterns).excludePathPatterns(excludePathPatterns);
super.addInterceptors(registry);
}
}