从项目中春季导入扩展和实现类

Question

我有两个（网络）项目，第二个项目使用第一个扩展类的方式。 我什至不知道我的项目的设计是否正确，但事实是我在服务器启动期间遇到错误，而且我也不知道是否存在设计错误：

-ProjectBird

package com.mycompany.dao;

public interface BirdDao{
     public void saveFly(Fly fly);
}

package com.mycompany.dao.impl;

public class BirdDaoImpl implements BirdDao{
   public BirdDaoImpl(){
   }
   public void saveFly(Fly fly){
       System.out.println("I'm saving flight data...");
   }
}

-ProjectFalcon

package com.mycompany.myunit.dao;

public interface FalconDao {
  public void saveHunt(Hunt hunt);
}

package com.mycompany.myunit.dao.impl;

import com.mycompany.dao.impl.BirdDaoImpl;

public class FalconDaoImpl extends BirdDaoImpl implements FalconDao{
  public FalconDaoImpl(){
  }

  public void saveHunt(Hunt hunt){
     System.out.println("I'm saving hunt data... poor prey!");
  }
}

当我尝试在服务器上运行此架构时，Spring引发异常：

平台：Eclipse Luna 4.4 Spring Tool Suite 3.6.1

Severe: Context initialization failed
org.springframework.beans.factory.BeanDefinitionStoreException: Failed to load bean class: com.mycompany.myunit.dao.impl.FalconDaoImpl; nested exception is java.io.FileNotFoundException: class path resource [com/mycompany/dao/impl/BirdDaoImpl.class] cannot be opened because it does not exist
    at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:162)
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:305)
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:243)
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:254)
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:94)
    at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:609)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:464)
    at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:658)
    at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:624)
    at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:672)
    at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:543)
    at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:484)
    at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136)
    at javax.servlet.GenericServlet.init(GenericServlet.java:241)
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1206)
    at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1026)
    at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4421)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4734)
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:799)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:779)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:601)
    at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1079)
    at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:1002)
    at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:506)
    at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1317)
    at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:324)
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:142)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1065)
    at org.apache.catalina.core.StandardHost.start(StandardHost.java:840)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1057)
    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
    at org.apache.catalina.core.StandardService.start(StandardService.java:525)
    at org.apache.catalina.core.StandardServer.start(StandardServer.java:754)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:595)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
Caused by: java.io.FileNotFoundException: class path resource [com/mycompany/dao/impl/BirdDaoImpl.class] cannot be opened because it does not exist
    at org.springframework.core.io.ClassPathResource.getInputStream(ClassPathResource.java:172)
    at org.springframework.core.type.classreading.SimpleMetadataReader.<init>(SimpleMetadataReader.java:50)
    at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:82)
    at org.springframework.core.type.classreading.CachingMetadataReaderFactory.getMetadataReader(CachingMetadataReaderFactory.java:102)
    at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:77)
    at org.springframework.context.annotation.ConfigurationClassParser.asSourceClass(ConfigurationClassParser.java:564)
    at org.springframework.context.annotation.ConfigurationClassParser$SourceClass.getSuperClass(ConfigurationClassParser.java:740)
    at org.springframework.context.annotation.ConfigurationClassParser.doProcessConfigurationClass(ConfigurationClassParser.java:287)
    at org.springframework.context.annotation.ConfigurationClassParser.processConfigurationClass(ConfigurationClassParser.java:218)
    at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:176)
    at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:158)
    ... 39 more

在Eclipse上是否存在设计错误或配置错误？

• ProjectBird列在POM中
• 在设计期间，Eclipse上没有错误或问题

谢谢！

Answer 1

事实上，这种设计不能很好地工作...

如果未在某些配置中指示项目之间的依赖关系，它将无法正常工作，即使如此，在两个Web项目之间建立依赖关系听起来也不好。

如果您需要重用一个类或扩展供其他项目使用的一个类，则此方案非常适合将一个或多个类作为依赖项包含在一个jar中，并将该唯一的依赖项导入两个项目中。

一个更清晰的示例是，当您具有服务层和Web层时，我们可以将Web层（http控制器和视图）放在一个项目中，而将服务层（服务接口和实现）放在另一个项目中，并在它们之间建立依赖关系。 Web项目和服务项目，可以通过将jar作为依赖项导入Web项目或在我们使用maven的情况下将其声明为依赖项来完成。