@Scope(“prototype") bean 作用域不创建新 bean [英] @Scope("prototype") bean scope not creating new bean

问题描述

我想在我的控制器中使用一个带注释的原型 bean.但是 spring 正在创建一个单例 bean.这是代码:

I want to use a annotated prototype bean in my controller. But spring is creating a singleton bean instead. Here is the code for that:

@Component
@Scope("prototype")
public class LoginAction {

  private int counter;

  public LoginAction(){
    System.out.println(" counter is:" + counter);
  }
  public String getStr() {
    return " counter is:"+(++counter);
  }
}

控制器代码:

@Controller
public class HomeController {
    @Autowired
    private LoginAction loginAction;

    @RequestMapping(value="/view", method=RequestMethod.GET)
    public ModelAndView display(HttpServletRequest req){
        ModelAndView mav = new ModelAndView("home");
        mav.addObject("loginAction", loginAction);
        return mav;
    }

    public void setLoginAction(LoginAction loginAction) {
        this.loginAction = loginAction;
    }

    public LoginAction getLoginAction() {
        return loginAction;
    }
    }

速度模板:

 LoginAction counter: ${loginAction.str}

Spring config.xml 已启用组件扫描:

Spring config.xml has component scanning enabled:

    <context:annotation-config />
    <context:component-scan base-package="com.springheat" />
    <mvc:annotation-driven />

我每次都得到一个递增的计数.想不通我哪里错了！

I'm getting an incremented count each time. Can't figure out where am I going wrong!

更新

按照 @gkamal 的建议，我制作了 HomeController webApplicationContext-知道它解决了问题.

As suggested by @gkamal, I made HomeController webApplicationContext-aware and it solved the problem.

更新代码:

@Controller
public class HomeController {

    @Autowired
    private WebApplicationContext context;

    @RequestMapping(value="/view", method=RequestMethod.GET)
    public ModelAndView display(HttpServletRequest req){
        ModelAndView mav = new ModelAndView("home");
        mav.addObject("loginAction", getLoginAction());
        return mav;
    }

    public LoginAction getLoginAction() {
        return (LoginAction) context.getBean("loginAction");
    }
}

推荐答案

Scope 原型意味着每次你向 spring(getBean 或依赖注入)请求一个实例时，它会创建一个新实例并给出一个引用.

Scope prototype means that every time you ask spring (getBean or dependency injection) for an instance it will create a new instance and give a reference to that.

>

在您的示例中，创建了一个新的 LoginAction 实例并将其注入到您的 HomeController 中.如果您有另一个控制器向其中注入 LoginAction，您将获得不同的实例.

In your example a new instance of LoginAction is created and injected into your HomeController . If you have another controller into which you inject LoginAction you will get a different instance.

如果您希望每次调用都有不同的实例 - 那么您每次都需要调用 getBean - 注入单例 bean 将无法实现这一点.

If you want a different instance for each call - then you need to call getBean each time - injecting into a singleton bean will not achieve that.

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