java如何使用JAXB读取XML文件？

Question

我使用JAXB从XML模式生成Java类。现在我想用这些类读取一个XML文件，但不行。我试着这样做

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

得到这个例外

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)

我不明白怎么了

我试图用悬垂的Piyush生成的代码和类来获取CoordSystem名称

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());

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

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

Answer 1

我想建议你这样做

 jaxbUnmarshaller.setSchema(schemaLocation);

通过这样做，您可以检查xml是否正在根据xsd进行验证，还可以通过读取SAXException或JAXBEException的stacktrace来找出xml中的问题所在

更新：

这是生成的java类的链接

Generated Java Classes

下面是xml的解组代码，并对xsd进行验证

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

Answer 2

如果从XML模式生成JAXB模型，那么应该在包名上生成JAXBContext，而不是类

你应该做：

JAXBContext.newInstance("com.example.foo");

而不是：

JAXBContext.newInstance(com.example.foo.Bar.class);

示例

• http://blog.bdoughan.com/2010/09/processing-atom-feeds-with-jaxb.html