@ConstructorProperties注释不适用于&#39;name&#39;属性 <constructor-arg> 标签

Question

Spring 5.1.6 documents on page 19 suggests that to inject value for constructor using 'name' attribute one should use @ConstructorProperties annotation.

Well in my workspace I am trying it with following classes

ConstDICls.java

package src.spring.core;

import java.beans.ConstructorProperties;

public class ConstDICls 
{
    private boolean flag;
    private String str;

    @ConstructorProperties({"flag", "str"})
    ConstDICls(boolean flag, String str)
    {
        this.flag = flag;
        this.str = str;
    }

    public void constMeth()
    {
        System.out.println("flag : "+flag+" str : "+str);
    }
}

spring1.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN 2.0//EN" "http://www.springframework.org/dtd
/spring-beans-2.0.dtd">

<beans>
    <bean id="constdi" class="src.spring.core.ConstDICls">
        <constructor-arg name="flag" value="true"/>
        <constructor-arg name="str" value="Spring5"/>
    </bean>
</beans>

SpringCheck.java

package src.spring.core;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SpringCheck
{
    public static void main(String[] args) 
    {
        ApplicationContext context = new ClassPathXmlApplicationContext("spring1.xml");
        ConstDICls constdi = (ConstDICls)context.getBean("constdi");
        constdi.constMeth();
    }
}

While running SpringCheck.java, I am getting following error

Exception in thread "main" org.springframework.beans.factory.xml.XmlBeanDefinitionStoreException: Line 7 in XML document from class path resource [spring1.xml] is invalid; nested exception is org.xml.sax.SAXParseException; lineNumber: 7; columnNumber: 46; Attribute "name" must be declared for element type "constructor-arg".

Full error log is below

Exception in thread "main" org.springframework.beans.factory.xml.XmlBeanDefinitionStoreException: Line 7 in XML document from class path resource [spring1.xml] is invalid; nested exception is org.xml.sax.SAXParseException; lineNumber: 7; columnNumber: 46; Attribute "name" must be declared for element type "constructor-arg".
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:404)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:336)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:304)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:188)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:224)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:195)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:257)
    at org.springframework.context.support.AbstractXmlApplicationContext.loadBeanDefinitions(AbstractXmlApplicationContext.java:128)
    at org.springframework.context.support.AbstractXmlApplicationContext.loadBeanDefinitions(AbstractXmlApplicationContext.java:94)
    at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:133)
    at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:636)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:521)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:144)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:85)
    at src.spring.core.SpringCheck.main(SpringCheck.java:10)
Caused by: org.xml.sax.SAXParseException; lineNumber: 7; columnNumber: 46; Attribute "name" must be declared for element type "constructor-arg".
    at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(Unknown Source)
    at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.error(Unknown Source)
    at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(Unknown Source)
    at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(Unknown Source)
    at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(Unknown Source)
    at com.sun.org.apache.xerces.internal.impl.dtd.XMLDTDValidator.addDTDDefaultAttrsAndValidate(Unknown Source)
    at com.sun.org.apache.xerces.internal.impl.dtd.XMLDTDValidator.handleStartElement(Unknown Source)
    at com.sun.org.apache.xerces.internal.impl.dtd.XMLDTDValidator.emptyElement(Unknown Source)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanStartElement(Unknown Source)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(Unknown Source)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(Unknown Source)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
    at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
    at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
    at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(Unknown Source)
    at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(Unknown Source)
    at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(Unknown Source)
    at org.springframework.beans.factory.xml.DefaultDocumentLoader.loadDocument(DefaultDocumentLoader.java:77)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadDocument(XmlBeanDefinitionReader.java:434)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:392)
    ... 14 more

Please tell me how to fix this.

Thanks Jay

Answer 1

You are using a very old way of validating an XML document, the DTD. As the filename of the DTD suggests it was written for Spring 2.0, which didn't have the name attribute back then.

You shouldn't be using the DTD but a more recent way of validating the XML by using the XSD.

<beans  xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
        xsi:schemaLocation="http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd">

This will have the proper schema for the XML.