Spring HandlerInterceptors如何实例化? [英] How are Spring HandlerInterceptors instantiated?

问题描述

每个请求是否都有Spring HandlerInterceptors的新实例?

Is there a new instance of Spring HandlerInterceptors for each request?

我在Spring中有一个拦截器，其中有一个类字段.

I have an interceptor in Spring, which has a class field.

public class MyInterceptor extends HandlerInterceptorAdapter {
    Private boolean state = false;

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {
        state = true;
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) {
        if (state == true) {
        System.out.println("Success");
        }
}

如果使用此拦截器，它将始终打印成功"吗? (无论同时有多少个线程在执行此操作?)

If this interceptor is used will it always print "Success"? (No matter how many threads are doing this at the same time?)

推荐答案

拦截器的实例化方式取决于将其配置为Bean的方式.如果您没有为bean明确指定范围，那么它将像其他任何bean一样成为单例，因此state字段将由所有请求共享.

How the interceptor is instantiated depends how you configiure it as a bean. If you don't explicitly specify a scope for the bean, then it'll be a singleton like any other bean, and so the state field will be shared by all requests.

从这个意义上讲，拦截器与控制器没有什么不同-请注意将对话状态放入控制器，因为对象将在请求之间共享.

In this sense, interceptors are no different to controllers - be very careful about putting conversation state in them, since the objects will be shared across requests.

如果您确实需要有状态的拦截器，并且不想在请求之间共享状态，请使用ar

if you really need a stateful interceptor and you don't want to share the state between requests, then use a request-scoped bean.

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