Java 如何在Spring中注入文本文件作为资源？

我想以

org.springframework.core.io.Resource

的形式插入一个文本文件，但在访问资源时，我不断得到

NullPointerException

：

@UIScope
@VaadinComponent
public class TestUI extends CustomComponent {
    @Value("C:/workspace/test/src/main/resources/VAADIN/themes/mytheme/layout/test.txt")
    private Resource txt;

    public TestUI() {
        txt.getInputStream(); //NPE
    }
}

我做错了什么

java.lang.NullPointerException: null
    at de.TestUI.<init>(TestUI.java:24)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:148)
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:89)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1069)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1021)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:504)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
    at org.springframework.beans.factory.support.AbstractBeanFactory$2.getObject(AbstractBeanFactory.java:343)
    at org.vaadin.spring.internal.UIStore.get(UIStore.java:73)
    at org.vaadin.spring.internal.UIStore.get(UIStore.java:64)
    at org.vaadin.spring.internal.VaadinUIScope.get(VaadinUIScope.java:54)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:338)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1017)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:960)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:858)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:480)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:289)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1185)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
    at org.springframework.beans.factory.support.AbstractBeanFactory$2.getObject(AbstractBeanFactory.java:343)
    at org.vaadin.spring.internal.UIStore.get(UIStore.java:73)
    at org.vaadin.spring.internal.UIStore.get(UIStore.java:64)
    at org.vaadin.spring.internal.VaadinUIScope.get(VaadinUIScope.java:54)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:338)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1017)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:960)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:858)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:480)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:289)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1185)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
    at org.springframework.beans.factory.support.AbstractBeanFactory$2.getObject(AbstractBeanFactory.java:343)
    at org.vaadin.spring.internal.UIStore.get(UIStore.java:73)
    at org.vaadin.spring.internal.UIStore.get(UIStore.java:64)
    at org.vaadin.spring.internal.VaadinUIScope.get(VaadinUIScope.java:54)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:338)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:296)
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:985)
    at org.vaadin.spring.servlet.internal.AbstractSpringAwareUIProvider.createInstance(AbstractSpringAwareUIProvider.java:93)
    at com.vaadin.server.communication.UIInitHandler.getBrowserDetailsUI(UIInitHandler.java:200)
    at com.vaadin.server.communication.UIInitHandler.synchronizedHandleRequest(UIInitHandler.java:73)
    at com.vaadin.server.SynchronizedRequestHandler.handleRequest(SynchronizedRequestHandler.java:37)
    at com.vaadin.server.VaadinService.handleRequest(VaadinService.java:1387)
    at com.vaadin.server.VaadinServlet.service(VaadinServlet.java:238)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:108)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
    at org.apache.catalina.valves.RemoteIpValve.invoke(RemoteIpValve.java:683)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1721)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1679)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:744)

java.lang.NullPointerException:null
在de.TestUI.（TestUI.java:24）
位于sun.reflect.NativeConstructorAccessorImpl.newInstance0（本机方法）
位于sun.reflect.NativeConstructorAccessorImpl.newInstance（NativeConstructorAccessorImpl.java:57）
在sun.reflect.DelegatingConstructorAccessorImpl.newInstance（DelegatingConstructorAccessorImpl.java:45）
位于java.lang.reflect.Constructor.newInstance（Constructor.java:526）
位于org.springframework.beans.BeanUtils.InstanceClass（BeanUtils.java:148）
位于org.springframework.beans.factory.support.SimpleInstallationStrategy.instantiate（SimpleInstallationStrategy.java:89）
位于org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.InstanceBean（AbstractAutowireCapableBeanFactory.java:1069）
位于org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance（AbstractAutowireCapableBeanFactory.java:1021）
位于org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean（AbstractAutowireCapableBeanFactory.java:504）
位于org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean（AbstractAutowireCapableBeanFactory.java:475）
位于org.springframework.beans.factory.support.AbstractBeanFactory$2.getObject（AbstractBeanFactory.java:343）
位于org.vaadin.spring.internal.UIStore.get（UIStore.java:73）
位于org.vaadin.spring.internal.UIStore.get（UIStore.java:64）
位于org.vaadin.spring.internal.VaadinUIScope.get（VaadinUIScope.java:54）
位于org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean（AbstractBeanFactory.java:338）
位于org.springframework.beans.factory.support.AbstractBeanFactory.getBean（AbstractBeanFactory.java:195）
位于org.springframework.beans.factory.support.DefaultListableBeanFactory.FindAuthories（DefaultListableBeanFactory.java:1017）
位于org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency（DefaultListableBeanFactory.java:960）
位于org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency（DefaultListableBeanFactory.java:858）
位于org.springframework.beans.factory.annotation.AutoWiredNotationBeanPostProcessor$AutoWiredFeldElement.inject（AutoWiredNotationBeanPostProcessor.java:480）
位于org.springframework.beans.factory.annotation.InjectionMetadata.inject（InjectionMetadata.java:87）
位于org.springframework.beans.factory.annotation.AutoWiredNotationBeanPostProcessor.postProcessPropertyValues（AutoWiredNotationBeanPostProcessor.java:289）
位于org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean（AbstractAutowireCapableBeanFactory.java:1185）
位于org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean（AbstractAutowireCapableBeanFactory.java:537）
位于org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean（AbstractAutowireCapableBeanFactory.java:475）
位于org.springframework.beans.factory.support.AbstractBeanFactory$2.getObject（AbstractBeanFactory.java:343）
位于org.vaadin.spring.internal.UIStore.get（UIStore.java:73）
位于org.vaadin.spring.internal.UIStore.get（UIStore.java:64）
位于org.vaadin.spring.internal.VaadinUIScope.get（VaadinUIScope.java:54）
位于org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean（AbstractBeanFactory.java:338）
位于org.springframework.beans.factory.support.AbstractBeanFactory.getBean（AbstractBeanFactory.java:195）
位于org.springframework.beans.factory.support.DefaultListableBeanFactory.FindAuthories（DefaultListableBeanFactory.java:1017）
位于org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency（DefaultListableBeanFactory.java:960）
位于org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency（DefaultListableBeanFactory.java:858）
位于org.springframework.beans.factory.annotation.AutoWiredNotationBeanPostProcessor$AutoWiredFeldElement.inject（AutoWiredNotationBeanPostProcessor.java:480）
位于org.springframework.beans.factory.annotation.InjectionMetadata.inject（InjectionMetadata.java:87）
位于org.springframework.beans.factory.annotation.AutoWiredNotationBeanPostProcessor.postProcessPropertyValues（AutoWiredNotationBeanPostProcessor.java:289）
位于org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean（AbstractAutowireCapableBeanFactory.java:1185）
位于org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean（AbstractAutowireCapableBeanFactory.java:537）
位于org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean（AbstractAutowireCapableBeanFactory.java:475）
位于org.springframework.beans.factory.support.AbstractBeanFactory$2.getObject（AbstractBeanFactory.java:343）
位于org.vaadin.spring.internal.UIStore.get（UIStore.java:73）
位于org.vaadin.spring.internal.UIStore.get（UIStore.java:64）
位于org.vaadin.spring.internal.VaadinUIScope.get（VaadinUIScope.java:54）
位于org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean（AbstractBeanFactory.java:338）
位于org.springframework.beans.factory.support.AbstractBeanFactory.getBean（AbstractBeanFactory.java:200）
位于org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean（DefaultListableBeanFactory.java:296）
位于org.springframework.context.support.AbstractApplicationContext.getBean（AbstractApplicationContext.java:985）
位于org.vaadin.spring.servlet.internal.AbstractSpringAwareiProvider.createInstance（AbstractSpringAwareiProvider.java:93）
位于com.vaadin.server.communication.UIInitHandler.getBr