将 Spring bean 注入使用 new() 创建的外部类答案

【问题标题】：Injecting Spring bean to an outside class created with new()将 Spring bean 注入使用 new() 创建的外部类
【发布时间】：2014-08-20 10:30:03
【问题描述】：

我正在尝试在 Class 中使用 spring bean。我正在从另一个 spring bean 访问这个类。我曾尝试使用AutoWireCapableBeanFacory 和@Configurable + AspectJ LTW，但我一次又一次地得到java.lang.UnsupportedOperationException。

我的场景如下：

ServiceOneImpl 调用MyClass，而MyClass 使用另一个名为MyService(autowired)的bean

//-------------------ServiceOne--------------
@Service("serviceOne")
public class ServiceOneImpl implements ServiceOne {
   @Override
   public void myMethod() {
       ClassA obj = new ClassA(arg1,arg2);
       obj.doSometing();

   } 
}

//-------------------MyService-------------
@Service("myService")
public class MyServiceImpl implements MyService {
   @Override
   public MyDTO getConfiguration(String arg) {
      return myDao.getConfiguration(arg);
   }
}

//-------------------MyClass--------------
@Component
public Class MyClass {

   @Autowired
   private MyService myService;

   private MyDTO myDTO;

   private String mailhost;
   private String arg1;
   private String arg2;

   public A() {
   }

   public A(String param1, String param2) {
       ServletContext context = (ServletContext) FacesContext.getCurrentInstance().getExternalContext().getContext();
       ApplicationContext applicationContext = WebApplicationContextUtils.getWebApplicationContext(context);   

       applicationContext.getAutowireCapableBeanFactory().
       autowireBeanProperties(this, AutowireCapableBeanFactory.AUTOWIRE_AUTODETECT,
       true);
       myDTO = myService.getConfiguration(); 
       mailhost = myDTO.getMailhost();

      //Do some process
   }
   public doSometing() {
      //Do some process
   }       
}

但我得到java.lang.UnsupportedOperationException MyService 没有自动连接，它返回空值

javax.faces.el.EvaluationException: java.lang.UnsupportedOperationException
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:102)
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
at javax.faces.component.UICommand.broadcast(UICommand.java:315)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:794)
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1259)
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:593)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:329)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:248)
at com.beo.atlas.common.filter.ClientSideCacheClearingFilter.doFilter(ClientSideCacheClearingFilter.java:34)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:280)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:248)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:154)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:150)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:199)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:110)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:50)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:108)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersisten

我正在使用SpringFramework 4.0.3.RELEASE

我无法解决此问题。如果有人给我一些启示，那对我会有很大的帮助

提前致谢

iMmo

【问题讨论】：

所有这些似乎都是 Spring Beans，那你为什么要使用 new 呢？而是在 Spring 上下文中配置工厂。
@Component 标签对我来说是一个错误，因为我认为使用它会使它成为一个 bean，实际上 'MyClass' 是一个通用类，我需要使用构造函数重载来调用该类，而我的项目负责人希望将它与新的 MyClass(...) 构造函数一起使用。
我仍然认为最干净的方法是在 Spring 中为类创建一个工厂，它可以在类中注入更多的依赖项。

标签： java spring spring-mvc

【解决方案1】：

除非您有充分的理由这样做，否则当您希望 Spring 将 bean 连接到对象时，请不要使用 new。并避免将域类绑定到 Spring。

恕我直言，您最好使用自定义构建器 bean：

public class ABuilder {
   @Autowired
   private MyService myService;

   public A getA(String param1, String param2) {
       A a = new A(param1, param2);
       a.setMyDTO(myService.getConfiguration()); 
       a.setMailhost(myDTO.getMailhost());
       return a;
   }
}

并相应地修改ServiceOne：

//-------------------ServiceOne--------------
@Autowired
ABuilder aBuilder;

@Service("serviceOne")
public class ServiceOneImpl implements ServiceOne {
   @Override
   public void myMethod() {
       ClassA obj = aBuilder.getA(arg1, arg2);
       obj.doSometing();
   } 
}

这样，A（或MyClass或ClassA）对Spring没有显式依赖，将通过其构建器注入其他bean。

当然，这不是真正的代码（参数和命名不一致），但你的也不是......

【讨论】：

感谢兄弟的宝贵建议。我会看看它，我一定会尝试的。但是我通过将@Lazy 添加到 Autowired bean 来实现它，目前似乎一切正常，我不认为我的解决方案是最合适的，顺便说一句，我不能在这里使用确切的代码，因为我担心专有法会给问题带来麻烦我:)

【解决方案2】：

请补充：

<context:spring-configured />

进入你的spring配置，

然后在 MyClass 类中添加 @Configurable 而不是 @Component！

【讨论】：

我试过@Configurable 和 -javaagent:spring-aspect.jar 但没有效果，我在我的问题中提到过

【解决方案3】：

我通过向自动装配属性添加@Lazy 注释解决了这个问题。

完整代码供日后参考：

//-------------------ServiceOne--------------
@Service("serviceOne")
public class ServiceOneImpl implements ServiceOne {
   @Override
   public void myMethod() {
       ClassA obj = new ClassA(arg1,arg2);
       obj.doSometing();

   } 
}

//-------------------MyService-------------
@Service("myService")
public class MyServiceImpl implements MyService {
   @Override
   public MyDTO getConfiguration(String arg) {
      return myDao.getConfiguration(arg);
   }
}

//-------------------MyClass--------------
@Component
public Class MyClass {

   @Autowired
   @Lazy
   private MyService myService;

   private MyDTO myDTO;

   private String mailhost;
   private String arg1;
   private String arg2;

   public A() {
   }

   public A(String param1, String param2) {
       ServletContext context = (ServletContext) FacesContext.getCurrentInstance().getExternalContext().getContext();
       ApplicationContext applicationContext = WebApplicationContextUtils.getWebApplicationContext(context);   

       applicationContext.getAutowireCapableBeanFactory().autowireBeanProperties(this,
                AutowireCapableBeanFactory.AUTOWIRE_BY_NAME,true);
       myDTO = myService.getConfiguration(); 
       mailhost = myDTO.getMailhost();

      //Do some process
   }
   public doSometing() {
      //Do some process
   }       
}

希望对某人有所帮助:)

【讨论】：