使用JAXB分析xml文件

Question

我正在实现一个简单的xml解析器，但遇到了一个问题：初始化JAXBContext时引发异常。

这是我的代码(对于这个问题来说可能太多了，但我试图只包括重要的部分(：

解析器本身：

package com.andreiyusupau.jaxbparser.parser;
import com.andreiyusupau.jaxbparser.model.Parent;
import com.andreiyusupau.jaxbparser.model.Root;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;
import java.io.File;
import java.util.Collection;
public class JaxbParser {
public Collection<Parent> parse(String inputXml) throws JAXBException  {
JAXBContext jc = JAXBContext.newInstance(Root.class);
Unmarshaller unmarshaller = jc.createUnmarshaller();
Root root = (Root) unmarshaller.unmarshal(new File(inputXml));
return root.getElements();
}
}

Main：

public class Main {
public static final String FILE_NAME = "data.xml";
public static void main(String[] args) throws JAXBException {
JaxbParser jaxbParser = new JaxbParser();
Collection<Parent> elements= jaxbParser.parse(FILE_NAME);
for (Parent element : elements) {
System.out.println(element.toString());
}
}
}

类(getter、setter和toString隐藏(：

import javax.xml.bind.annotation.*;
import java.util.List;
@XmlRootElement(name = "root")
@XmlAccessorType(XmlAccessType.FIELD)
public class Root {
@XmlElements({
@XmlElement(name = "ChildA", type = ChildA.class),
@XmlElement(name = "ChildB", type = ChildB.class),
})
private List<Parent> elements;
public Root() {
}
}

import org.eclipse.persistence.oxm.annotations.XmlPath;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlSeeAlso;
import javax.xml.bind.annotation.XmlTransient;
@XmlTransient
@XmlSeeAlso({ChildA.class, ChildB.class})
public class Parent {
@XmlAttribute
private int id;
@XmlElement(name = "name")
private String name;
@XmlElement(name = "parameter")
private String parameter;
@XmlPath("parameter/@parameterAttr")
private String parameterAttribute;
@XmlPath("similar/a/text()")
private int a;
@XmlPath("similar/b/text()")
private int b;
@XmlPath("different/similar/text()")
private String similar;
@XmlPath("different/similar/@similarAttr")
private String similarAttribute;
public Parent() {
}
}

import org.eclipse.persistence.oxm.annotations.XmlPath;
import javax.xml.bind.annotation.XmlRootElement;
@XmlRootElement(name = "childA")
public class ChildA extends Parent {
@XmlPath("different/differentA/text()")
private String differentA;
@XmlPath("different/differentA/@attrA")
private String differentAttributeA;
public ChildA() {
}
}

import org.eclipse.persistence.oxm.annotations.XmlPath;
import javax.xml.bind.annotation.XmlRootElement;
@XmlRootElement(name = "childB")
public class ChildB extends Parent {
@XmlPath("different/differentB1/text()")
private String differentB1;
@XmlPath("different/differentB1/@attrB1")
private String differentAttributeB1;
@XmlPath("different/differentB2/text()")
private String differentB2;
@XmlPath("different/differentB2/@attrB2")
private String differentAttributeB2;
public ChildB() {
}
}

最后是一个xml文件本身：

<?xml version="1.1" encoding="UTF-8"?>
<root xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation = "schema.xsd">
<childA id="ID-1">
<name>Name</name>
<parameter parameterAttr="a">b</parameter>
<similarGroup>
<a>1</a>
<b>2</b>
</similarGroup>
<different>
<similar similarAttr="n">2</similar>
<differentA attrA="n">100</differentA>
</different>
</childA>
<childB id="ID-2">
<name>Name</name>
<parameter parameterAttr="c">d</parameter>
<similarGroup>
<a>6</a>
<b>8</b>
</similarGroup>
<different>
<similar similarAttr="g">7</similar>
<differentB1 attrB1="5">100</differentB1>
<differentB2>100</differentB2>
</different>
</childB>
</root>

以及POM-xml:中的依赖关系

<dependency>
<groupId>jakarta.xml.bind</groupId>
<artifactId>jakarta.xml.bind-api</artifactId>
<version>2.3.3</version>
</dependency>
<dependency>
<groupId>org.eclipse.persistence</groupId>
<artifactId>eclipselink</artifactId>
<version>3.0.0-M1</version>
</dependency>
<dependency>
<groupId>org.glassfish.jaxb</groupId>
<artifactId>jaxb-runtime</artifactId>
<version>2.3.3</version>
</dependency>

jaxb.properties

javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory

编译并运行此代码会出现以下异常：

Exception in thread "main" java.lang.NoClassDefFoundError: jakarta/xml/bind/JAXBContext
at java.base/java.lang.Class.getDeclaredMethods0(Native Method)
at java.base/java.lang.Class.privateGetDeclaredMethods(Class.java:3166)
at java.base/java.lang.Class.getMethodsRecursive(Class.java:3307)
at java.base/java.lang.Class.getMethod0(Class.java:3293)
at java.base/java.lang.Class.getMethod(Class.java:2106)
at javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:249)
at javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:240)
at javax.xml.bind.ContextFinder.find(ContextFinder.java:345)
at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:691)
at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:632)
at com.andreiyusupau.jaxbparser.parser.JaxbParser.parse(JaxbParser.java:15)
at com.andreiyusupau.jaxbparser.Main.main(Main.java:15)
Caused by: java.lang.ClassNotFoundException: jakarta.xml.bind.JAXBContext
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:581)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
... 12 more

也许有人知道我该怎么解决？

更新：

用jaxb-api替换jakarta.xml.bind-api后，我出现以下异常：

Exception in thread "main" javax.xml.bind.JAXBException: ClassCastException: attempting to cast jar:file:/C:/Users/Nevermind/.m2/repository/javax/xml/bind/jaxb-api/2.3.1/jaxb-api-2.3.1.jar!/javax/xml/bind/JAXBContext.class to jar:file:/C:/Users/Nevermind/.m2/repository/javax/xml/bind/jaxb-api/2.3.1/jaxb-api-2.3.1.jar!/javax/xml/bind/JAXBContext.class.  Please make sure that you are specifying the proper ClassLoader.    
at javax.xml.bind.ContextFinder.handleClassCastException(ContextFinder.java:157)
at javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:300)
at javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:286)
at javax.xml.bind.ContextFinder.find(ContextFinder.java:391)
at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:721)
at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:662)
at com.andreiyusupau.jaxbparser.parser.JaxbParser.parse(JaxbParser.java:15)
at com.andreiyusupau.jaxbparser.Main.main(Main.java:15)

在以下行中引发异常：JAXBContext jc = JAXBContext.newInstance(Root.class);

有什么建议吗？

Answer 1

我建议替换依赖

<dependency>
<groupId>jakarta.xml.bind</groupId>
<artifactId>jakarta.xml.bind-api</artifactId>
<version>2.3.3</version>
</dependency>

带有

<dependency>
<groupId>javax.xml.bind</groupId>
<artifactId>jaxb-api</artifactId>
<version>2.3.1</version>
</dependency>

jakarta.xml.bind来自Jakarta EE，org.glassfish.jaxb来自旧的Java EE。

Answer 2

执行mvn dependency:tree(或mvn help:effective-pom(以查看哪些依赖项最终会出现在类路径上。

尝试使用这些：

<!-- XML -->
<dependency>
<groupId>jakarta.xml.bind</groupId>
<artifactId>jakarta.xml.bind-api</artifactId>
<version>2.3.3</version>
</dependency>
<dependency>
<groupId>org.glassfish.jaxb</groupId>
<artifactId>jaxb-runtime</artifactId>
<scope>runtime</scope>
<version>2.3.3</version>
</dependency>

JakartaEE正在清理所有遗留的JavaEEjavax.*API，并使用正确的maven元数据作为jakarta.*API再次发布。