springboot 中怎么向 Runnable 中传递一个该线程独占的局部变量? - V2EX
gzk329
V2EX    Java

springboot 中怎么向 Runnable 中传递一个该线程独占的局部变量?

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  •   gzk329 Dec 16, 2022 2454 views
    This topic created in 1242 days ago, the information mentioned may be changed or developed.

    ThreadLocal 可以做吗?

     a.setParam(xxx); //然后丢到线程池执行 @Component class A implements Runnable{ private B param; } 

    这么写 这个 param 会被覆盖

    9 replies    2022-12-18 03:17:44 +08:00
    gzk329
        1
    gzk329  
    OP
       Dec 16, 2022
    之前一直是通过构造函数传参数的 但是那样就不能被 spring 管理了 用起来麻烦
    kaneg
        2
    kaneg  
       Dec 16, 2022
    Spring 默认 bean 是单例的,里面不要放有状态的 field ,否则所有用到该 bean 的地方都会受影响。用 ThreadLocal 也是不行的,因为线程池里的线程你控制不了,没法设置 thread local 变量。
    ZeawinL
        3
    ZeawinL  
       Dec 17, 2022 via iPhone
    Spring 用多例试试?
    yazinnnn
        4
    yazinnnn  
       Dec 17, 2022
    这叫成员变量。。。
    agmtopy
        5
    agmtopy  
       Dec 17, 2022
    Class A 为什么需要用原型啊?如果想要把 B 作为成员变量传进去,就另外用一个 class 来实现就可以的,一般称为 context 之类的
    itechify
        6
    itechify  
    PRO
       Dec 17, 2022 via Android
    class A 之所以用 @Component ,因为 A 类用了 service 之类的 spring 管理的类?
    darling19961030
        7
    darling19961030  
       Dec 17, 2022
    关键字 TaskDecorator RequestContextHoder? InheritableThreadLocal 阿里 TTL
    darling19961030
        8
    darling19961030  
       Dec 17, 2022
    @darling19961030 RequestContextHolder
    nieyuanhong
        9
    nieyuanhong  
       Dec 18, 2022
    Spirng bean 默认全局单例,也就是所有线程都共享一份 A 的实例,你如果在一处改了`param: B`,那所有线程下的成员变量`param: B`当然都会改变。
    简单的做法就是用一个`Map`,以线程为键,`param: B` 为值,存放所有线程的`param: B`。
    最后在 getter 和 setter 做下线程判断,就 OK 了。
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