Spring注解自动装配报错：Cannot find the declaration of element 'beans'

问题 #

学习Spring注解实现自动装配时，尝试通过@Autowired将Address对象注入Emp类，运行时抛出错误：Cannot find the declaration of element 'beans'。

相关代码 #

Emp.java #

package com.collection.autowire;

import org.springframework.beans.factory.annotation.Autowired;

public class Emp {

    @Autowired
    private Address address;

    // getter、setter方法及构造方法已省略
}

Address.java #

package com.collection.autowire;

public class Address {
    private String streetName;
    private String city;

    // getter、setter方法及构造方法已省略
}

Test.java #

package com.collection.autowire;

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

public class Test {

    public static void main(String[] args) {
        ClassPathXmlApplicationContext container = new 
            ClassPathXmlApplicationContext("com/collection/autowire/autoconfig.xml");

        Emp emp = container.getBean("emp1", Emp.class);
        System.out.println(emp);
    }
}

autoconfig.xml #

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

    <context:annotation-config/> 

    <bean class="com.collection.autowire.Address" name="address">
        <property name="streetName" value="temp" />
        <property name="city" value="Pune" />
    </bean>

    <bean class="com.collection.autowire.Emp" name="emp1" />
</beans>

pom.xml #

<groupId>com.springcore</groupId>
<artifactId>springcore</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

<name>springcore</name>
<url>http://maven.apache.org</url>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>

<dependencies>
    <!-- Spring Core -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
        <version>5.3.20</version>
    </dependency>

    <!-- Spring Context -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>5.3.20</version>
    </dependency>

    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>3.8.1</version>
        <scope>test</scope>
    </dependency>

    <dependency>
        <groupId>javax.annotation</groupId>
        <artifactId>javax.annotation-api</artifactId>
        <version>1.3.2</version>
    </dependency>
</dependencies>

错误日志 #

Exception in thread "main" org.springframework.beans.factory.xml.XmlBeanDefinitionStoreException: Line 11 in XML document from class path resource [com/collection/autowire/autoconfig.xml] is invalid; nested exception is org.xml.sax.SAXParseException; lineNumber: 11; columnNumber: 4; cvc-elt.1.a: Cannot find the declaration of element 'beans'.
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:402)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:338)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:310)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:196)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:232)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:203)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:265)
    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:130)
    at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:671)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:553)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:144)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:85)
    at com.collection.autowire.Test.main(Test.java:10)
Caused by: org.xml.sax.SAXParseException; lineNumber: 11; columnNumber: 4; cvc-elt.1.a: Cannot find the declaration of element 'beans'.
    at java.xml/com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:204)
    at java.xml/com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.error(ErrorHandlerWrapper.java:135)
    at java.xml/com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:396)
    at java.xml/com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:327)
    at java.xml/com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:284)
    at java.xml/com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.handleStartElement(XMLSchemaValidator.java:2133)
    at java.xml/com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.startElement(XMLSchemaValidator.java:830)
    at java.xml/com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.scanStartElement(XMLNSDocumentScannerImpl.java:374)
    at java.xml/com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl$NSContentDriver.scanRootElementHook(XMLNSDocumentScannerImpl.java:613)
    at java.xml/com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:3079)
    at java.xml/com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(XMLDocumentScannerImpl.java:836)
    at java.xml/com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:605)
    at java.xml/com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:112)
    at java.xml/com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:542)
    at java.xml/com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:889)
    at java.xml/com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:825)
    at java.xml/com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:141)
    at java.xml/com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:247)
    at java.xml/com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:342)
    at org.springframework.beans.factory.xml.DefaultDocumentLoader.loadDocument(DefaultDocumentLoader.java:77)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadDocument(XmlBeanDefinitionReader.java:432)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:390)
    ... 14 more

解决方案 #

报错根源是XML配置文件中命名空间与Schema位置的协议不匹配：

• beans标签的xmlns使用了http协议，但xsi:schemaLocation中对应的Schema地址用了https，导致XML解析器无法找到对应的Schema声明。

修改autoconfig.xml的beans命名空间，将http改为https，保持与Schema位置协议一致：

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

修改后重新运行，XML解析器就能正确找到Schema声明，解决Cannot find the declaration of element 'beans'错误。

内容的提问来源于stack exchange，提问作者Shreyash Pawar