如何解决用JAXB解析xml文件
我正在实现一个简单的xml解析器,并遇到了一个问题: 初始化JAXBContext时会引发异常。
这是我的代码(这个问题可能太多了,但是我尝试仅包括重要部分):
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();
}
}
主要:
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被隐藏):
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() {
}
}
<?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>
和POM xml中的依赖项:
<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
编译并运行此代码将产生以下异常:
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:
将jakarta.xml.bind-api
替换为jaxb-api
后,我遇到以下异常:
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)
在行中引发异常:
JAXBContext jc = JAXBContext.newInstance(Root.class);
有什么建议吗?
解决方法
我建议替换依赖项
<dependency>
<groupId>jakarta.xml.bind</groupId>
<artifactId>jakarta.xml.bind-api</artifactId>
<version>2.3.3</version>
</dependency>
使用
<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
来自较旧的Java EE。
执行mvn dependency:tree
(或mvn help:effective-pom
)以查看哪些依赖项最终出现在您的类路径上。
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正在清理所有旧版JavaEE javax.*
API,并使用适当的maven元数据作为jakarta.*
API再次发布。
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