如何使用 JAXB 读取 XML 文件? [英] How to read an XML file with JAXB?

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本文介绍了如何使用 JAXB 读取 XML 文件?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我使用 JAXB 从 XML 模式生成 Java 类.现在我想用这些类读取 XML 文件，但不能.我试试这个

I use JAXB to generate Java classes from XML schema. Now I want to read an XML file with these classes, but can't. I try this 

    JAXBContext jaxbContext = JAXBContext.newInstance(STDMP.class);
    Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
    STDMP ts = (STDMP)jaxbUnmarshaller.unmarshal(xml_gkuzu);
    System.out.println(ts.getEDocument().getSender().getName());

并得到这个异常

Exception in thread "main" java.lang.NullPointerException
at java.util.EnumMap.<init>(EnumMap.java:113)
at com.sun.xml.bind.v2.model.impl.RuntimeEnumLeafInfoImpl.<init>(RuntimeEnumLeafInfoImpl.java:87)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.createEnumLeafInfo(RuntimeModelBuilder.java:109)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.createEnumLeafInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:229)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:104)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:214)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:99)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getTypeInfo(ModelBuilder.java:320)
at com.sun.xml.bind.v2.model.impl.SingleTypePropertyInfoImpl.getTarget(SingleTypePropertyInfoImpl.java:94)
at com.sun.xml.bind.v2.model.impl.RuntimeAttributePropertyInfoImpl.getTarget(RuntimeAttributePropertyInfoImpl.java:66)
at com.sun.xml.bind.v2.model.impl.RuntimeAttributePropertyInfoImpl.getTarget(RuntimeAttributePropertyInfoImpl.java:54)
at com.sun.xml.bind.v2.model.impl.SingleTypePropertyInfoImpl.ref(SingleTypePropertyInfoImpl.java:88)
at com.sun.xml.bind.v2.model.impl.RuntimeAttributePropertyInfoImpl.ref(RuntimeAttributePropertyInfoImpl.java:70)
at com.sun.xml.bind.v2.model.impl.RuntimeAttributePropertyInfoImpl.ref(RuntimeAttributePropertyInfoImpl.java:54)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:260)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:104)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:214)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:99)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getTypeInfo(ModelBuilder.java:320)
at com.sun.xml.bind.v2.model.impl.TypeRefImpl.calcRef(TypeRefImpl.java:96)
at com.sun.xml.bind.v2.model.impl.TypeRefImpl.getTarget(TypeRefImpl.java:73)
at com.sun.xml.bind.v2.model.impl.RuntimeTypeRefImpl.getTarget(RuntimeTypeRefImpl.java:62)
at com.sun.xml.bind.v2.model.impl.RuntimeTypeRefImpl.getTarget(RuntimeTypeRefImpl.java:55)
at com.sun.xml.bind.v2.model.impl.ElementPropertyInfoImpl$1.get(ElementPropertyInfoImpl.java:78)
at com.sun.xml.bind.v2.model.impl.ElementPropertyInfoImpl$1.get(ElementPropertyInfoImpl.java:76)
at java.util.AbstractList$Itr.next(AbstractList.java:345)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:260)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:104)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:214)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:99)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getTypeInfo(ModelBuilder.java:320)
at com.sun.xml.bind.v2.model.impl.TypeRefImpl.calcRef(TypeRefImpl.java:96)
at com.sun.xml.bind.v2.model.impl.TypeRefImpl.getTarget(TypeRefImpl.java:73)
at com.sun.xml.bind.v2.model.impl.RuntimeTypeRefImpl.getTarget(RuntimeTypeRefImpl.java:62)
at com.sun.xml.bind.v2.model.impl.RuntimeTypeRefImpl.getTarget(RuntimeTypeRefImpl.java:55)
at com.sun.xml.bind.v2.model.impl.ElementPropertyInfoImpl$1.get(ElementPropertyInfoImpl.java:78)
at com.sun.xml.bind.v2.model.impl.ElementPropertyInfoImpl$1.get(ElementPropertyInfoImpl.java:76)
at java.util.AbstractList$Itr.next(AbstractList.java:345)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:260)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:104)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:214)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:99)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getTypeInfo(ModelBuilder.java:320)
at com.sun.xml.bind.v2.model.impl.TypeRefImpl.calcRef(TypeRefImpl.java:96)
at com.sun.xml.bind.v2.model.impl.TypeRefImpl.getTarget(TypeRefImpl.java:73)
at com.sun.xml.bind.v2.model.impl.RuntimeTypeRefImpl.getTarget(RuntimeTypeRefImpl.java:62)
at com.sun.xml.bind.v2.model.impl.RuntimeTypeRefImpl.getTarget(RuntimeTypeRefImpl.java:55)
at com.sun.xml.bind.v2.model.impl.ElementPropertyInfoImpl$1.get(ElementPropertyInfoImpl.java:78)
at com.sun.xml.bind.v2.model.impl.ElementPropertyInfoImpl$1.get(ElementPropertyInfoImpl.java:76)
at java.util.AbstractList$Itr.next(AbstractList.java:345)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:260)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:104)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:214)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:99)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getTypeInfo(ModelBuilder.java:320)
at com.sun.xml.bind.v2.model.impl.TypeRefImpl.calcRef(TypeRefImpl.java:96)
at com.sun.xml.bind.v2.model.impl.TypeRefImpl.getTarget(TypeRefImpl.java:73)
at com.sun.xml.bind.v2.model.impl.RuntimeTypeRefImpl.getTarget(RuntimeTypeRefImpl.java:62)
at com.sun.xml.bind.v2.model.impl.RuntimeTypeRefImpl.getTarget(RuntimeTypeRefImpl.java:55)
at com.sun.xml.bind.v2.model.impl.ElementPropertyInfoImpl$1.get(ElementPropertyInfoImpl.java:78)
at com.sun.xml.bind.v2.model.impl.ElementPropertyInfoImpl$1.get(ElementPropertyInfoImpl.java:76)
at java.util.AbstractList$Itr.next(AbstractList.java:345)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:260)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:104)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:214)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:99)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getTypeInfo(ModelBuilder.java:320)
at com.sun.xml.bind.v2.model.impl.TypeRefImpl.calcRef(TypeRefImpl.java:96)
at com.sun.xml.bind.v2.model.impl.TypeRefImpl.getTarget(TypeRefImpl.java:73)
at com.sun.xml.bind.v2.model.impl.RuntimeTypeRefImpl.getTarget(RuntimeTypeRefImpl.java:62)
at com.sun.xml.bind.v2.model.impl.RuntimeTypeRefImpl.getTarget(RuntimeTypeRefImpl.java:55)
at com.sun.xml.bind.v2.model.impl.ElementPropertyInfoImpl$1.get(ElementPropertyInfoImpl.java:78)
at com.sun.xml.bind.v2.model.impl.ElementPropertyInfoImpl$1.get(ElementPropertyInfoImpl.java:76)
at java.util.AbstractList$Itr.next(AbstractList.java:345)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:260)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:104)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:214)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:99)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getTypeInfo(ModelBuilder.java:320)
at com.sun.xml.bind.v2.model.impl.TypeRefImpl.calcRef(TypeRefImpl.java:96)
at com.sun.xml.bind.v2.model.impl.TypeRefImpl.getTarget(TypeRefImpl.java:73)
at com.sun.xml.bind.v2.model.impl.RuntimeTypeRefImpl.getTarget(RuntimeTypeRefImpl.java:62)
at com.sun.xml.bind.v2.model.impl.RuntimeTypeRefImpl.getTarget(RuntimeTypeRefImpl.java:55)
at com.sun.xml.bind.v2.model.impl.ElementPropertyInfoImpl$1.get(ElementPropertyInfoImpl.java:78)
at com.sun.xml.bind.v2.model.impl.ElementPropertyInfoImpl$1.get(ElementPropertyInfoImpl.java:76)
at java.util.AbstractList$Itr.next(AbstractList.java:345)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:260)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:104)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:214)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:99)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getTypeInfo(ModelBuilder.java:320)
at com.sun.xml.bind.v2.model.impl.TypeRefImpl.calcRef(TypeRefImpl.java:96)
at com.sun.xml.bind.v2.model.impl.TypeRefImpl.getTarget(TypeRefImpl.java:73)
at com.sun.xml.bind.v2.model.impl.RuntimeTypeRefImpl.getTarget(RuntimeTypeRefImpl.java:62)
at com.sun.xml.bind.v2.model.impl.RuntimeTypeRefImpl.getTarget(RuntimeTypeRefImpl.java:55)
at com.sun.xml.bind.v2.model.impl.ElementPropertyInfoImpl$1.get(ElementPropertyInfoImpl.java:78)
at com.sun.xml.bind.v2.model.impl.ElementPropertyInfoImpl$1.get(ElementPropertyInfoImpl.java:76)
at java.util.AbstractList$Itr.next(AbstractList.java:345)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:260)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:104)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:214)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:99)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getTypeInfo(ModelBuilder.java:320)
at com.sun.xml.bind.v2.model.impl.TypeRefImpl.calcRef(TypeRefImpl.java:96)
at com.sun.xml.bind.v2.model.impl.TypeRefImpl.getTarget(TypeRefImpl.java:73)
at com.sun.xml.bind.v2.model.impl.RuntimeTypeRefImpl.getTarget(RuntimeTypeRefImpl.java:62)
at com.sun.xml.bind.v2.model.impl.RuntimeTypeRefImpl.getTarget(RuntimeTypeRefImpl.java:55)
at com.sun.xml.bind.v2.model.impl.ElementPropertyInfoImpl$1.get(ElementPropertyInfoImpl.java:78)
at com.sun.xml.bind.v2.model.impl.ElementPropertyInfoImpl$1.get(ElementPropertyInfoImpl.java:76)
at java.util.AbstractList$Itr.next(AbstractList.java:345)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:260)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:104)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:214)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:99)
at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:85)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getTypeInfo(ModelBuilder.java:320)
at com.sun.xml.bind.v2.model.impl.ModelBuilder.getTypeInfo(ModelBuilder.java:335)
at com.sun.xml.bind.v2.runtime.JAXBContextImpl.getTypeInfoSet(JAXBContextImpl.java:465)
at com.sun.xml.bind.v2.runtime.JAXBContextImpl.<init>(JAXBContextImpl.java:303)
at com.sun.xml.bind.v2.runtime.JAXBContextImpl.<init>(JAXBContextImpl.java:142)
at com.sun.xml.bind.v2.runtime.JAXBContextImpl$JAXBContextBuilder.build(JAXBContextImpl.java:1174)
at com.sun.xml.bind.v2.ContextFactory.createContext(ContextFactory.java:162)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:202)
at javax.xml.bind.ContextFinder.find(ContextFinder.java:363)
at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:574)
at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:522)
at net.sf.hibernate.examples.quickstart.hib_main.main(hib_main.java:83)

我不明白出了什么问题.

I don't understand what's wrong.

我尝试使用 Dangling Piyush 生成的代码和类来获取 CoordSystem Name.

I tried to get CoordSystem Name with code and classes generated by Dangling Piyush.

代码

        File xml_gkuzu = new File("D:/liferay-develop/workspace/cat_test/XML/GKUZU_53ce0a8e-13e1-4e4e-99d9-2f45ae786d33!chz.xml");
    JAXBContext jaxbContext = JAXBContext.newInstance(CoordSystem.class);
SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
Schema schema = factory.newSchema(new StreamSource(new File("D:/liferay-develop/workspace/cat_test/v2/STD_MP.xsd")));
Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
jaxbUnmarshaller.setSchema(schema);
CoordSystem cs = (CoordSystem)jaxbUnmarshaller.unmarshal(xml_gkuzu);
System.out.println(cs.getName());

但是在 CoordSystem cs = (CoordSystem)jaxbUnmarshaller.unmarshal(xml_gkuzu); 行得到一个异常；

Exception in thread "main" javax.xml.bind.UnmarshalException: unexpected element (uri:"", local:"STD_MP"). Expected elements are <{}Coord_System>

推荐答案

我想建议做

 jaxbUnmarshaller.setSchema(schemaLocation);

通过这样做，您可以检查您的 xml 是否针对 xsd 进行验证，您还可以通过读取 SAXException 或 JAXBException 的堆栈跟踪来找出 xml 中的问题所在.

By doing this you can check whether your xml is validating against xsd or not and you can also find out where is the problem in xml by reading the stacktrace of SAXException or JAXBException.

更新:

这是生成的java类的链接

This is the link for generated java classses

生成的 Java 类

以下是针对 xsd 进行验证的 xml 解组代码.

And follwing is the unmarshalling code for xml with validation against xsd.

import java.io.File;
import javax.xml.XMLConstants;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;
import javax.xml.transform.stream.StreamSource;
import javax.xml.validation.Schema;
import javax.xml.validation.SchemaFactory;

import org.xml.sax.SAXException;

import com.piyush.STDMP;


public class Test {

    /**
     * @param args
     * @throws JAXBException 
     * @throws SAXException 
     */
    public static void main(String[] args) throws JAXBException, SAXException {
        JAXBContext jaxbContext = JAXBContext.newInstance(STDMP.class);
        SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
        Schema schema = factory.newSchema(new StreamSource(new File("C:/Users/CDAC/workspace/Testing/src/STD_MP.xsd")));
        Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
        jaxbUnmarshaller.setSchema(schema);
        STDMP ts = (STDMP)jaxbUnmarshaller.unmarshal(new File("E:/Testing.xml"));

        System.out.println(ts.getCoordSystems());
        System.out.println(ts.getEDocument());

    }

     }

请根据您的机器更改xsd和xml位置.

Please change the xsd and xml location according to your machine.

这篇关于如何使用 JAXB 读取 XML 文件?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！

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