问题
Im working on a java project where i need to read some objects from an XML file, do some processing which will alter the object´s atributes and then write the Object to another XML file. For that purpose, i am using JAXB with its marshalling and unmarshalling capabilities, each of them in a method, like this:
private MyObject unmarshallXMLFile(String file) {
MyObject t=null;
try {
jc = JAXBContext.newInstance("foo.bar");
Unmarshaller unmarshaller = jc.createUnmarshaller();
SchemaFactory sf = SchemaFactory.newInstance(javax.xml.XMLConstants.W3C_XML_SCHEMA_NS_URI);
unmarshaller.setSchema(sf.newSchema(new File("MySchema.xsd")));
t = (Task) unmarshaller.unmarshal(new File(file));
} catch (JAXBException e) {
e.printStackTrace();
} catch (SAXException e) {
e.printStackTrace();
}
return t;
}
private void marshallXMLFile(String file) {
task.setReplay(Boolean.TRUE);
Marshaller marshaller;
try {
marshaller = jc.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, new Boolean(true));
marshaller.marshal(task, new FileOutputStream(file));
} catch (JAXBException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
The problem is that automatically-generated namespace prefixes such as ns2 or ns3 keep appearing in the output file, and then when i want to reuse this files with the unmarshallXMLFile method (i will be using the output files as input again later) it wont get validated against the schema, and throws a org.xml.sax.SAXParseException. Here are the files i wrote:
XML Schema: MySchema.xsd
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.example.org/MySchema"
xmlns:spm="http://www.example.org/MySchema"
elementFormDefault="qualified"
attributeFormDefault="qualified">
<element name="task" >
<complexType>
<sequence>
<element name="replay" type="boolean" default="false"/>
<element name="threads" type="spm:spThread" maxOccurs="unbounded" minOccurs="1" />
</sequence>
</complexType>
</element>
<complexType name="spThread">
<sequence>
<element name="SPThreadID" type="int" />
<element name="durtime" minOccurs="0" default="0">
<simpleType>
<restriction base="int">
<minInclusive value="0" />
</restriction>
</simpleType>
</element>
<element name="minexecutions" minOccurs="0" default="0">
<simpleType>
<restriction base="int">
<minInclusive value="0" />
</restriction>
</simpleType>
</element>
<element name="numThreads" type="int" />
<element name="procedures" type="spm:procedure" minOccurs="1"
maxOccurs="unbounded" />
</sequence>
</complexType>
<complexType name="procedure">
<sequence>
<element name="id" type="int" minOccurs="1" />
<element name="name" type="string" minOccurs="1" />
<element name="weight" minOccurs="1">
<simpleType>
<restriction base="int">
<minInclusive value="0" />
<maxInclusive value="100" />
</restriction>
</simpleType>
</element>
<element name="parameterPool" type="spm:parameter" nillable="true"
minOccurs="0" maxOccurs="unbounded" />
</sequence>
</complexType>
<complexType name="parameter">
<sequence>
<element name="name" type="string" minOccurs="1" />
<element name="dataType" type="spm:parameterDataType" default="integer"/>
<element name="parmType" type="spm:parameterType" default="in"
minOccurs="0" />
<element name="minValue" type="string"/>
<element name="maxValue" type="string"/>
<element name="value" type="string"/>
</sequence>
</complexType>
<simpleType name="parameterDataType">
<restriction base="string">
<enumeration value="integer" />
<enumeration value="varchar" />
<enumeration value="char" />
</restriction>
</simpleType>
<simpleType name="parameterType">
<restriction base="string">
<enumeration value="in" />
<enumeration value="out" />
<enumeration value="in_out" />
</restriction>
</simpleType>
</schema>
input file:
<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<task xmlns="http://www.example.org/MySchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.example.org/MySchema MySchema.xsd ">
<replay>true</replay>
<threads>
<SPThreadID>0</SPThreadID>
<durtime>10</durtime>
<minexecutions>2</minexecutions>
<numThreads>3</numThreads>
<procedures>
<id>1</id>
<name>run</name>
<weight>15</weight>
<parameterPool>
<name>energy</name>
<dataType>integer</dataType>
<parmType>in</parmType>
<minValue>10</minValue>
<maxValue>50</maxValue>
<value>11</value>
</parameterPool>
<parameterPool>
<name>speed</name>
<dataType>integer</dataType>
<parmType>in</parmType>
<minValue>12</minValue>
<maxValue>80</maxValue>
<value>13</value>
</parameterPool>
</procedures>
</threads>
</task>
output file (without any processing whatsoever: just unmarshalling and marshalling back with the methods mentioned earlier)
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ns2:task xmlns="http://www.example.org/MySchema" xmlns:ns2="http://www.example.org/MySchema.xsd">
<replay>true</replay>
<threads>
<SPThreadID>0</SPThreadID>
<durtime>10</durtime>
<minexecutions>2</minexecutions>
<numThreads>3</numThreads>
<procedures>
<id>1</id>
<name>run</name>
<weight>15</weight>
<parameterPool>
<name>energy</name>
<dataType>integer</dataType>
<parmType>in</parmType>
<minValue>10</minValue>
<maxValue>50</maxValue>
<value>11</value>
</parameterPool>
<parameterPool>
<name>speed</name>
<dataType>integer</dataType>
<parmType>in</parmType>
<minValue>12</minValue>
<maxValue>80</maxValue>
<value>13</value>
</parameterPool>
</procedures>
</threads>
</ns2:task>
exception (when using the ouput file again as an input):
javax.xml.bind.UnmarshalException
- with linked exception:
[org.xml.sax.SAXParseException: cvc-elt.1: The declaration of the element'ns3:task' could not be found.]
at javax.xml.bind.helpers.AbstractUnmarshallerImpl.createUnmarshalException(AbstractUnmarshallerImpl.java:326)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.createUnmarshalException(UnmarshallerImpl.java:500)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(UnmarshallerImpl.java:206)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal(UnmarshallerImpl.java:175)
at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:148)
at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:153)
at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:162)
at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:180)
at Test.main(Test.java:48)
Caused by: org.xml.sax.SAXParseException: cvc-elt.1: The declaration of the element'ns3:task' could not be found.
at org.apache.xerces.util.ErrorHandlerWrapper.createSAXParseException(Unknown Source)
at org.apache.xerces.util.ErrorHandlerWrapper.error(Unknown Source)
at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source)
at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source)
at org.apache.xerces.impl.xs.XMLSchemaValidator.handleStartElement(Unknown Source)
at org.apache.xerces.impl.xs.XMLSchemaValidator.startElement(Unknown Source)
at org.apache.xerces.jaxp.validation.XMLSchemaValidatorHandler.startElement(Unknown Source)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.ValidatingUnmarshaller.startElement(ValidatingUnmarshaller.java:85)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.SAXConnector.startElement(SAXConnector.java:113)
at org.apache.xerces.parsers.AbstractSAXParser.startElement(Unknown Source)
at org.apache.xerces.impl.XMLNSDocumentScannerImpl.scanStartElement(Unknown Source)
at org.apache.xerces.impl.XMLNSDocumentScannerImpl$NSContentDispatcher.scanRootElementHook(Unknown Source)
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(Unknown Source)
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(UnmarshallerImpl.java:202)
... 6 more
I´ve been reading about the subject and tried loads of related answers, but none of them seems to remove the prefixes. I went trough this guide but the version of jaxb i am using does not support NamespacePrefixMapper. I tried using annotations as described here to configure the prefixes but that wouldnt work.
Maybe there is a way of getting rid of this namespace prefixes: all the forums, answers and discussions i´ve found talk about customizing this prefixes, i just want to get rid of them. But somehow it makes me think that i´m missing something in both my input file and schema. Are they well written? I would say that right there is the problem, because it is the first time i work with xml and xsd at this depth, and what i´ve done is only based on what i´ve found online. Any tips on improving the xml and xsd designs would be highly appreciated
should i be using some kind of prefixes in the input file or in the schema so the JAXB framework wont generate random prefixes at time of marshalling?
thanks in advance, i hope you guys can help me.
--
Thank you very much for the answer. In that way i can use the NamespacePrefixMapper. However, when i use it, my code keeps throwing exceptions when i run it:
Exception in thread "main" java.util.MissingResourceException: Can't find bundle for base name javax.xml.bind.Messages, locale de_DE
at java.util.ResourceBundle.throwMissingResourceException(ResourceBundle.java:863)
at java.util.ResourceBundle.getBundleImpl(ResourceBundle.java:832)
at java.util.ResourceBundle.getBundle(ResourceBundle.java:576)
at javax.xml.bind.Messages.format(Messages.java:47)
at javax.xml.bind.Messages.format(Messages.java:36)
at javax.xml.bind.PropertyException.<init>(PropertyException.java:99)
at javax.xml.bind.helpers.AbstractMarshallerImpl.setProperty(AbstractMarshallerImpl.java:349)
at com.sun.xml.internal.bind.v2.runtime.MarshallerImpl.setProperty(MarshallerImpl.java:527)
at Test.main(Test.java:95)
I found that it has to do something with a .properties file: i am not using anything like it, i havent changed anything.
回答1:
Instead of specifying the @XmlElement's namespace attribute in every element, it's simpler to annotate at package level.
You do that by creating a file package-info.java just underneath the package you want to annotate.
For example, if you want to annotate the package org.example, then a file named package-info.java must be placed within the directory org/example with the following content:
@javax.xml.bind.annotation.XmlSchema(namespace = "http://www.example.org/StoredProceduresSchema", elementFormDefault = javax.xml.bind.annotation.XmlNsForm.QUALIFIED)
package org.example;
It's important to note that you must annotate every package that contains classes that your plan to marshal or are referenced by those.
Hope this helps :)
回答2:
Try using a NamespacePrefixMapper:
NamespacePrefixMapper mapper = new NamespacePrefixMapper() {
public String getPreferredPrefix(String namespaceUri, String suggestion, boolean requirePrefix) {
return "";
}
};
marshaller.setProperty("com.sun.xml.bind.namespacePrefixMapper", mapper);
回答3:
Well, after some research, i tried using the @XMLElement tag on every attribute of the classes i am trying to serialize, specifying clearly what my namespace was, and using the same one on every attribute:
@XmlElement(required = true, name="myObjectPool", namespace="http://www.example.org/StoredProceduresSchema")
protected List<MyObject> myObjectPool;
It worked flawlessly: no more weird namespaces in the marshalled file.
I wanna thank for his answer: i tried that as well, but i got a weird language bundle related exception. Im glad this simpler approach solved the issue.
回答4:
Then you might be using a different JAXB implementation then the reference. Read this article and try again: http://blog.bdoughan.com/2011/11/jaxb-and-namespace-prefixes.html (or if you are lazy: replace com.sun.xml.bind.namespacePrefixMapper with com.sun.xml.internal.bind.namespacePrefixMapper)
回答5:
Java 7/8 solution
This problem is related to the default implementation JAXB Provider. I have found a solution using a different implementation: EclipseLink MOXy.
1. add the dependency inpom.xml
<dependency>
<groupId>org.eclipse.persistence</groupId>
<artifactId>org.eclipse.persistence.moxy</artifactId>
<version>2.5.0</version>
</dependency>`
javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory
move the file into the package model
3. create package-file.java into the model package@XmlSchema(xmlns = { @XmlNs(prefix = "video", namespaceURI = "http://www.google.com/schemas/sitemap-video/1.1"),
@XmlNs(prefix = "", namespaceURI = "http://www.sitemaps.org/schemas/sitemap/0.9")})
package it.my.sitemap.model;
import javax.xml.bind.annotation.XmlNs;
import javax.xml.bind.annotation.XmlSchema;
来源：https://stackoverflow.com/questions/6586304/jaxb-xml-object-marshalling-without-namespace-prefixes