@Scope("prototype")bean范围未创建新bean [英] @Scope("prototype") bean scope not creating new bean

问题描述

我想在控制器中使用带注释的原型bean.但是春天正在创建一个单例豆.这是该代码:

@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启用了组件扫描:

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

我每次都获得递增计数.无法弄清楚我要去哪里错了！

更新

以 @gkamal 的建议为例，我意识到HomeController webApplicationContext并解决了问题./p>

更新的代码:

@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");
    }
}

解决方案

作用域原型意味着每次您向spring(getBean或依赖项注入)请求实例时，它都会创建一个新实例并提供对该实例的引用.

在您的示例中，将创建一个LoginAction的新实例，并将其注入到HomeController中.如果您要向其中注入LoginAction的另一个控制器，您将获得一个不同的实例.

如果您希望每次调用都使用不同的实例-那么您每次都需要调用getBean-向单例bean中注入将无法实现这一目标.

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);
  }
}

Controller code:

@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;
    }
    }

Velocity template:

 LoginAction counter: ${loginAction.str}

Spring config.xml has component scanning enabled:

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

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

Update

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

updated code:

@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");
    }
}

解决方案

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.

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.

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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