org.springframework.beans.factory.parsing.BeanDefinitionParsingException，在bean定義解析異常期間出現意外故障

Question

嘗試運行簡單的Spring應用程序並獲取異常。

Car.java

public class Car { 

    private String carname; 
    private Engine engine; 
    public Car() { 
     System.out.println("Car Class.."); 
    } 

    public void setCarname(String carname) { 
     this.carname = carname; 
    } 
    public void setEngine(Engine engine) { 
     this.engine = engine; 
    } 

    public void printCarData(){ 
     System.out.println("Car Name : "+carname); 
     System.out.println("Model Year : "+engine.getModelyear()); 
    } 
} 

引擎的.java

public class Engine { 

    private String modelyear; 
    public Engine() { 
     System.out.println("Engine Class.."); 
    } 

    public String getModelyear() { 
     return modelyear; 
    } 

    public void setModelyear(String modelyear) { 
     this.modelyear = modelyear; 
    } 

} 

employee.xml

<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN 2.0//EN" 
      "http://www.springframework.org/dtd/spring-beans-2.0.dtd"> 


<beans> 

    <bean id="e" name="beans.Engine" class="beans.Engine"> 
     <property name="modelyear" value="2015" /> 

    </bean> 

</beans> 

car.xml

<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN 2.0//EN" 
      "http://www.springframework.org/dtd/spring-beans-2.0.dtd"> 


<beans> 

    <bean id="c" name="beans.Car" class="beans.Car"> 

     <property name="carname" value="Acura"></property> 
     <property name="engine" value="e"></property> 
    </bean> 

</beans> 

Client.java

public class client { 

    public static void main(String[] args) { 

     String files[] = new String[]{"resources/car.xml","resources/engine.xml"}; 
     //Resource resource = new ClassPathResource(files); 
     ApplicationContext app = new ClassPathXmlApplicationContext(files);//eager container 

    } 

} 

---

錯誤......

Exception in thread "main" org.springframework.beans.factory.parsing.BeanDefinitionParsingException: Configuration problem: Unexpected failure during bean definition parsing 
Offending resource: class path resource [resources/car.xml] 
Bean 'c'; nested exception is org.springframework.beans.factory.parsing.BeanDefinitionParsingException: Configuration problem: <constructor-arg> element must specify a ref or value 
Offending resource: class path resource [resources/car.xml] 
Bean 'c' 
    -> Constructor-arg 
    at org.springframework.beans.factory.parsing.FailFastProblemReporter.error(FailFastProblemReporter.java:68) 
    at org.springframework.beans.factory.parsing.ReaderContext.error(ReaderContext.java:85) 
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.error(BeanDefinitionParserDelegate.java:291) 
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseBeanDefinitionElement(BeanDefinitionParserDelegate.java:497) 
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseBeanDefinitionElement(BeanDefinitionParserDelegate.java:396) 
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseBeanDefinitionElement(BeanDefinitionParserDelegate.java:365) 
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.processBeanDefinition(DefaultBeanDefinitionDocumentReader.java:259) 
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseDefaultElement(DefaultBeanDefinitionDocumentReader.java:154) 
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:133) 
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:93) 
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:493) 
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:390) 
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:334) 
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:302) 
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:143) 
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:178) 
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:149) 
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:212) 
    at org.springframework.context.support.AbstractXmlApplicationContext.loadBeanDefinitions(AbstractXmlApplicationContext.java:126) 
    at org.springframework.context.support.AbstractXmlApplicationContext.loadBeanDefinitions(AbstractXmlApplicationContext.java:92) 
    at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:130) 
    at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:465) 
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:395) 
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139) 
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:93) 
    at test.client.main(client.java:14) 
Caused by: org.springframework.beans.factory.parsing.BeanDefinitionParsingException: Configuration problem: <constructor-arg> element must specify a ref or value 
Offending resource: class path resource [resources/car.xml] 
Bean 'c' 
    -> Constructor-arg 
    at org.springframework.beans.factory.parsing.FailFastProblemReporter.error(FailFastProblemReporter.java:68) 
    at org.springframework.beans.factory.parsing.ReaderContext.error(ReaderContext.java:85) 
    at org.springframework.beans.factory.parsing.ReaderContext.error(ReaderContext.java:80) 
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.error(BeanDefinitionParserDelegate.java:284) 
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parsePropertyValue(BeanDefinitionParserDelegate.java:938) 
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseConstructorArgElement(BeanDefinitionParserDelegate.java:800) 
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseConstructorArgElements(BeanDefinitionParserDelegate.java:684) 
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseBeanDefinitionElement(BeanDefinitionParserDelegate.java:481) 
    ... 22 more 

Answer 1

在你car.xml改變這樣的：

<property name="engine" value="e"></property> 

到：

<property name="engine" ref="e"></property> 

原因：

您的bean e是一個引擎類型。而這正是你的Car構造函數期望的，而不是一個值爲「e」的字符串。