|
|
| Line 7: |
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| | In the current JAXB RI, developed by Sun, there are a series of "proprietary" JAXB extensions that are available to provide advanced JAXB functionality outside of the JAXB spec (these extension classes reside in the '''com.sun.xml.bind''' package). | | In the current JAXB RI, developed by Sun, there are a series of "proprietary" JAXB extensions that are available to provide advanced JAXB functionality outside of the JAXB spec (these extension classes reside in the '''com.sun.xml.bind''' package). |
| | | | |
| − | The '''@XmlLocation''' annotation is one of these extensions - it allows the user to specify a property on the JAXB object that will be updated (upon unmarshalling) with that object's XML location information (i.e. the line number, column number, and system ID that points to this object's location in the XML input). | + | The '''IDResolver''' interface provided in the Sun JAXB implementation allows users to override the ID/IDREF processing of the JAXB runtime. |
| | | | |
| | This document will outline the design for an EclipseLink equivalent to this extension. | | This document will outline the design for an EclipseLink equivalent to this extension. |
| Line 14: |
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| | = Requirements = | | = Requirements = |
| | | | |
| − | * Deliver an '''@XmlLocation''' annotation in the EclipseLink library that will provide the same functionality as the Sun extension. | + | * Deliver an '''IDResolver''' interface in the EclipseLink library that will provide the same functionality as the Sun extension. |
| − | ** Line number | + | ** Given a String <tt>id</tt> and Object <tt>obj</tt>, allow the user to perform custom <tt>bind</tt> code |
| − | ** Column number | + | ** Given a String <tt>id</tt> and Class <tt>type</tt>, allow the user to perform custom <tt>resolve</tt> code |
| − | ** System ID, if applicable
| + | ** Provide the user a hook into <tt>startDocument()</tt> and <tt>endDocument()</tt> events |
| − | * Have zero impact on memory/performance if the user is not using '''@XmlLocation'''. | + | |
| | | | |
| | | | |
| | = Behaviour = | | = Behaviour = |
| | | | |
| − | * If an object containing an '''@XmlLocation''' property is unmarshalled, a '''Locator''' object will be created and set on the property, containing the XML location info.
| + | If an '''IDResolver''' has been set on the '''Unmarshaller''' (via properties), then the following things must happen during unmarshal: |
| | | | |
| − | * If an object with a populated '''Locator''' is marshalled to XML, the '''Locator''' information will appear in the resultant XML. | + | * The '''IDResolver''''s <tt>startDocument()</tt> method must be called when unmarshalling starts. |
| − | | + | * When an '''ID''' value is encountered during unmarshal, the '''IDResolver''''s <tt>bind</tt> method must be called, to bind the object to the ID. |
| − | * If XML is unmarshalled that contains actual '''Locator''' information (e.g. the example above), that information is not read in like a normal mapping; upon unmarshalling the '''Locator''' property will be set to reflect the current XML location. | + | * When an '''IDREF''' value is encountered during unmarshal, the '''IDResolver''''s <tt>resolve</tt> method must be used to obtain the object for the IDREF. |
| − | | + | * The '''IDResolver''''s <tt>endDocument()</tt> method must be called when unmarshalling completes. |
| − | * If an '''@XmlLocation''' property is also marked as '''@XmlTransient''', then '''Locator''' information will NOT appear in marshalled XML. | + | |
| − | | + | |
| − | | + | |
| − | Not all unmarshal sources will be able to provide XML location information. For example, unmarshalling from a '''File''' would be able to give you line, column and system ID (filename); system ID is not available when unmarshalling from an '''InputStream'''; unmarshalling from a '''Node''' would give you no XML location information at all.
| + | |
| − | | + | |
| − | | + | |
| − | {|{{BMTableStyle}}
| + | |
| − | |-{{BMTHStyle}}
| + | |
| − | ! Unmarshal Source
| + | |
| − | ! Line #
| + | |
| − | ! Column #
| + | |
| − | ! System ID
| + | |
| − | |-
| + | |
| − | | java.io.File
| + | |
| − | | [[Image:Ok_green.gif]]
| + | |
| − | | [[Image:Ok_green.gif]]
| + | |
| − | | [[Image:Ok_green.gif]]
| + | |
| − | |-
| + | |
| − | | java.io.InputStream
| + | |
| − | | [[Image:Ok_green.gif]]
| + | |
| − | | [[Image:Ok_green.gif]]
| + | |
| − | | [[Image:Delete.gif]]
| + | |
| − | |-
| + | |
| − | | java.io.Reader
| + | |
| − | | [[Image:Ok_green.gif]]
| + | |
| − | | [[Image:Ok_green.gif]]
| + | |
| − | | [[Image:Delete.gif]]
| + | |
| − | |-
| + | |
| − | | java.net.URL
| + | |
| − | | [[Image:Ok_green.gif]]
| + | |
| − | | [[Image:Ok_green.gif]]
| + | |
| − | | [[Image:Ok_green.gif]]
| + | |
| − | |-
| + | |
| − | | javax.xml.stream.XMLEventReader
| + | |
| − | | [[Image:Ok_green.gif]]
| + | |
| − | | [[Image:Ok_green.gif]]
| + | |
| − | | [[Image:Delete.gif]]
| + | |
| − | |-
| + | |
| − | | javax.xml.stream.XMLStreamReader
| + | |
| − | | [[Image:Ok_green.gif]]
| + | |
| − | | [[Image:Ok_green.gif]]
| + | |
| − | | [[Image:Delete.gif]]
| + | |
| − | |-
| + | |
| − | | org.w3c.dom.Node
| + | |
| − | | [[Image:Delete.gif]]
| + | |
| − | | [[Image:Delete.gif]]
| + | |
| − | | [[Image:Delete.gif]]
| + | |
| − | |-
| + | |
| − | | org.xml.sax.InputSource
| + | |
| − | | [[Image:Ok_green.gif]]
| + | |
| − | | [[Image:Ok_green.gif]]
| + | |
| − | | [[Image:Delete.gif]]
| + | |
| − | |}<br>
| + | |
| | | | |
| | | | |
| | = Configuration = | | = Configuration = |
| | | | |
| − | In order to use '''@XmlLocation''', the user must first have a property on their Java object (either a field or get/set pair) of type
| + | The user must implement the following interface: |
| − | '''org.xml.sax.Locator'''. The user can then specify that this property should be used to track XML location by using either EclipseLink Annotations or XML Bindings.
| + | |
| − | | + | |
| − | | + | |
| − | == Annotations ==
| + | |
| | | | |
| | <div style="width:800px"> | | <div style="width:800px"> |
| | <source lang="java"> | | <source lang="java"> |
| − | package org.eclipse.persistence.oxm.annotations; | + | package org.eclipse.persistence.jaxb; |
| | | | |
| − | import static java.lang.annotation.ElementType.FIELD; | + | import java.util.concurrent.Callable; |
| − | import static java.lang.annotation.ElementType.METHOD;
| + | |
| − | import static java.lang.annotation.RetentionPolicy.RUNTIME;
| + | |
| | | | |
| − | import java.lang.annotation.Retention; | + | import javax.xml.bind.ValidationEventHandler; |
| − | import java.lang.annotation.Target;
| + | |
| | | | |
| − | @Target({METHOD, FIELD})
| + | import org.xml.sax.SAXException; |
| − | @Retention(RUNTIME)
| + | |
| − | public @interface XmlLocation {}
| + | |
| − | </source>
| + | |
| − | </div>
| + | |
| | | | |
| | + | public interface IDResolver { |
| | | | |
| − | == XML Bindings ==
| + | public abstract Callable<?> resolve(String id, Class type) throws SAXException; |
| | | | |
| − | eclipselink_oxm_2_4.xsd:
| + | public abstract void bind(String id, Object obj) throws SAXException; |
| − | <div style="width:800px">
| + | |
| − | <source lang="xml">
| + | |
| − | ...
| + | |
| − | <xs:element name="xml-transient" substitutionGroup="java-attribute"> | + | |
| − | <xs:complexType>
| + | |
| − | <xs:complexContent>
| + | |
| − | <xs:extension base="java-attribute">
| + | |
| − | <xs:attribute name="xml-location" type="xs:boolean" default="false" />
| + | |
| − | </xs:extension>
| + | |
| − | </xs:complexContent>
| + | |
| − | </xs:complexType>
| + | |
| − | </xs:element>
| + | |
| − | ...
| + | |
| − | <xs:element name="xml-element" substitutionGroup="java-attribute">
| + | |
| − | <xs:complexType>
| + | |
| − | <xs:complexContent>
| + | |
| − | <xs:extension base="java-attribute">
| + | |
| − | ...
| + | |
| − | <xs:attribute name="xml-location" type="xs:boolean" default="false" />
| + | |
| − | </xs:extension>
| + | |
| − | </xs:complexContent>
| + | |
| − | </xs:complexType>
| + | |
| − | </xs:element>
| + | |
| − | ...
| + | |
| − | </source>
| + | |
| − | </div>
| + | |
| | | | |
| | + | public void startDocument(ValidationEventHandler eventHandler) throws SAXException; |
| | | | |
| − | == Config Options ==
| + | public void endDocument() throws SAXException; |
| − | | + | |
| − | The '''@XmlLocation''' feature does not expose any configuration options, it is merely a tagging annotation that indicates the property to be used for tracking XML location information.
| + | |
| − | | + | |
| − | | + | |
| − | = Examples =
| + | |
| − | | + | |
| − | The following examples refer to this XML instance document:
| + | |
| − | | + | |
| − | <div style="width:800px">
| + | |
| − | <source lang="xml">
| + | |
| − | <?xml version="1.0" encoding="UTF-8"?>
| + | |
| − | <customer>
| + | |
| − | <id>1872874</id>
| + | |
| − | <name>Bob Smith</name>
| + | |
| − | </customer>
| + | |
| − | </source>
| + | |
| − | </div>
| + | |
| − | | + | |
| − | | + | |
| − | == Example 1 ==
| + | |
| − | | + | |
| − | This example shows the most basic use case; the '''Locator''' field is annotated with '''@XmlLocation''' (or, in XML Bindings, the "xml-element" has its "xml-location" attribute set to "true").
| + | |
| − | | + | |
| − | Annotations:
| + | |
| − | <div style="width:800px">
| + | |
| − | <source lang="java">
| + | |
| − | import javax.xml.bind.annotation.*;
| + | |
| − | | + | |
| − | import org.eclipse.persistence.oxm.annotations.XmlLocation;
| + | |
| − | | + | |
| − | import org.xml.sax.Locator;
| + | |
| − | | + | |
| − | @XmlRootElement
| + | |
| − | public class Customer {
| + | |
| − | | + | |
| − | public int id;
| + | |
| − | | + | |
| − | public String name;
| + | |
| − | | + | |
| − | @XmlLocation
| + | |
| − | public Locator locator;
| + | |
| − | | + | |
| − | @Override
| + | |
| − | public String toString() { | + | |
| − | String loc = " noLoc";
| + | |
| − | if (locator != null) {
| + | |
| − | loc = " L" + locator.getLineNumber() +
| + | |
| − | " C" + locator.getColumnNumber() +
| + | |
| − | " " + locator.getSystemId();
| + | |
| − | }
| + | |
| − | | + | |
| − | return "Customer(" + name + ")" + loc;
| + | |
| − | }
| + | |
| | | | |
| | } | | } |
| Line 200: |
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| | </div> | | </div> |
| | | | |
| − | Equivalent XML Bindings:
| + | The user's '''IDResolver''' class can then be passed to the EclipseLink Unmarshaller through the <tt>addProperty()</tt> method: |
| − | <div style="width:800px"> | + | |
| − | <source lang="xml"> | + | |
| − | ...
| + | |
| − | <java-types>
| + | |
| − | <java-type name="Customer">
| + | |
| − | <xml-root-element />
| + | |
| − | <java-attributes>
| + | |
| − | <xml-element java-attribute="id" />
| + | |
| − | <xml-element java-attribute="name" />
| + | |
| − | <xml-element java-attribute="locator" xml-location="true" />
| + | |
| − | </java-attributes>
| + | |
| − | </java-type>
| + | |
| − | </java-types>
| + | |
| − | ...
| + | |
| − | </source>
| + | |
| − | </div>
| + | |
| | | | |
| − | When a '''Customer''' is unmarshalled, the '''Locator''' field is automatically set to contain the XML location information for that object. By default, if that object was then marshalled back to XML, the XML location information would be written out as well.
| |
| − |
| |
| − | Unmarshalling and Marshalling:
| |
| | <div style="width:800px"> | | <div style="width:800px"> |
| | <source lang="java"> | | <source lang="java"> |
| − | File f = new File("D:/temp/instance.xml"));
| |
| − | Customer c = jaxbContext.createUnmarshaller().unmarshal(f);
| |
| − |
| |
| − | System.out.println(c);
| |
| − |
| |
| − | // Output:
| |
| − | // Customer(Bob Smith) L15 C35 file:/D:/temp/instance.xml
| |
| − |
| |
| − | jaxbContext.createMarshaller().marshal(c, System.out);
| |
| − |
| |
| − | // Output:
| |
| − | // <?xml version="1.0" encoding="UTF-8"?>
| |
| − | // <customer>
| |
| − | // <id>1872874</id>
| |
| − | // <name>Bob Smith</name>
| |
| − | // <locator>
| |
| − | // <columnNumber>35</columnNumber>
| |
| − | // <lineNumber>15</lineNumber>
| |
| − | // <systemId>file:/D:/temp/instance.xml</systemId>
| |
| − | // </locator>
| |
| − | // </customer>
| |
| − | </source>
| |
| − | </div>
| |
| − |
| |
| − |
| |
| − | == Example 2 ==
| |
| − |
| |
| − | In most cases, you would not want XML location information written out during marshal, as this information reflects the location the object was unmarshalled FROM, not the location it is being marshalled TO. If XML location is encountered when unmarshalling XML, it would be ignored anyway, and instead the "fresh" XML location information would be used instead.
| |
| − |
| |
| − | To avoid writing out XML location during marshal operations, you can additionally annotate your '''@XmlLocation''' property with '''@XmlTransient''' (or, in XML Bindings, use "xml-transient" instead of "xml-element"):
| |
| − |
| |
| − | Annotations:
| |
| − | <div style="width:800px">
| |
| − | <source lang="java">
| |
| − | import javax.xml.bind.annotation.*;
| |
| − |
| |
| − | import org.eclipse.persistence.oxm.annotations.XmlLocation;
| |
| − |
| |
| − | import org.xml.sax.Locator;
| |
| − |
| |
| − | @XmlRootElement
| |
| − | public class Customer {
| |
| − |
| |
| − | public int id;
| |
| − |
| |
| − | public String name;
| |
| − |
| |
| − | @XmlLocation
| |
| − | @XmlTransient
| |
| − | public Locator locator;
| |
| − |
| |
| − | ...
| |
| − |
| |
| − | }
| |
| − | </source>
| |
| − | </div>
| |
| − |
| |
| − | Equivalent XML Bindings:
| |
| − | <div style="width:800px">
| |
| − | <source lang="xml">
| |
| − | ...
| |
| − | <java-types>
| |
| − | <java-type name="Customer">
| |
| − | <xml-root-element />
| |
| − | <java-attributes>
| |
| − | <xml-element java-attribute="id" />
| |
| − | <xml-element java-attribute="name" />
| |
| − | <xml-transient java-attribute="locator" xml-location="true" />
| |
| − | </java-attributes>
| |
| − | </java-type>
| |
| − | </java-types>
| |
| | ... | | ... |
| | + | JAXBContext ctx = ... |
| | + | Unmarshaller u = ctx.createUnmarshaller(); |
| | + | u..setProperty("org.eclipse.persistence.jaxb.IDResolver", new MyIDResolver()); |
| | </source> | | </source> |
| | </div> | | </div> |
| | | | |
| − | Unmarshalling and Marshalling:
| |
| − | <div style="width:800px">
| |
| − | <source lang="java">
| |
| − | File f = new File("D:/temp/instance.xml"));
| |
| − | Customer c = jaxbContext.createUnmarshaller().unmarshal(f);
| |
| | | | |
| − | System.out.println(c);
| + | == XML Bindings == |
| | | | |
| − | // Output:
| + | ??? |
| − | // Customer(Bob Smith) L15 C35 file:/D:/temp/instance.xml
| + | |
| | | | |
| − | jaxbContext.createMarshaller().marshal(c, System.out);
| |
| | | | |
| − | // Output:
| + | = Examples = |
| − | // <?xml version="1.0" encoding="UTF-8"?>
| + | |
| − | // <customer>
| + | |
| − | // <id>1872874</id>
| + | |
| − | // <name>Bob Smith</name>
| + | |
| − | // </customer>
| + | |
| − | </source>
| + | |
| − | </div>
| + | |
| − | | + | |
| − | | + | |
| − | == Example 3 ==
| + | |
| − | | + | |
| − | Accessor methods can be annotated instead of the actual Java field:
| + | |
| − | | + | |
| − | <div style="width:800px">
| + | |
| − | <source lang="java">
| + | |
| − | import javax.xml.bind.annotation.*;
| + | |
| − | | + | |
| − | import org.eclipse.persistence.oxm.annotations.XmlLocation;
| + | |
| − | | + | |
| − | import org.xml.sax.Locator;
| + | |
| − | | + | |
| − | @XmlRootElement
| + | |
| − | public class Customer {
| + | |
| − | | + | |
| − | private int id;
| + | |
| − | | + | |
| − | private String name;
| + | |
| − | | + | |
| − | private Locator locator;
| + | |
| − | | + | |
| − | @XmlLocation
| + | |
| − | public Locator getLocator() {
| + | |
| − | return this.locator;
| + | |
| − | }
| + | |
| − | | + | |
| − | public void setLocator(Locator l) {
| + | |
| − | this.locator = l;
| + | |
| − | }
| + | |
| − | | + | |
| − | ...
| + | |
| − | | + | |
| − | }
| + | |
| − | </source>
| + | |
| − | </div>
| + | |
| | | | |
| | | | |
| | = Design = | | = Design = |
| − |
| |
| − | When processing XML through our various parsing mechanisms (UnmarshalRecord, SAXDocumentBuilder, XMLStreamReaderReader, etc), a Locator object is supplied by the underlying parser libraries. This Locator is constantly updated throughout the unmarshalling process (with the location of the currently parsed node). When parsing a startElement(), if that element equates to a Descriptor that is location-aware, the Locator will be cloned at that point, and stored on the UnmarshalRecord, indicating the XML Location of that object in XML.
| |
| − |
| |
| − |
| |
| − | * New annotation: '''org.eclipse.persistence.oxm.annotations.XmlLocation'''
| |
| − | * New boolean "'''xml-location'''" flag on "xml-transient" and "xml-element" in XML Bindings
| |
| − | ** Must be added to new 2.4 schema - eclipselink_oxm_2_4.xsd
| |
| − | ** Corresponding updates to o.e.p.jaxb.xmlmodel classes
| |
| − | <br>
| |
| − | * New field on XMLDescriptor: '''boolean isLocationAware'''
| |
| − | <br>
| |
| − | * New field on UnmarshalRecord: '''Locator xmlLocation''' (each object instance has its own UnmarshalRecord, and this will be set only if Descriptor isLocationAware)
| |
| − | <br>
| |
| − | * New field on Property: '''boolean isXmlLocation'''
| |
| − | ** Property is set up for isXmlLocation in AnnotationsProcessor and XMLProcessor
| |
| − | <br>
| |
| − | * MappingsGenerator: in generateMapping(), create a specialized XMLCompositeObjectMapping for the Locator property
| |
| − | * New class: '''NullInstantiationPolicy''' - we want to create a regular mapping for the Locator, but will never be instantiating it like a regular mapping - its value will be set manually during parsing. Plus, Locator does not have a default constructor. This InstantiationPolicy simply returns null for buildNewInstance().
| |
| − | <br>
| |
| − | * New constants in XMLConstants: '''LOCATOR_CLASS''' and '''LOCATOR_CLASS_NAME'''
| |
| − | <br>
| |
| − | * New JAXBException ("XmlLocation is only allowed on properties of type org.xml.sax.Locator, but [{0}] is of type [{1}].")
| |
| | | | |
| | | | |
In the current JAXB RI, developed by Sun, there are a series of "proprietary" JAXB extensions that are available to provide advanced JAXB functionality outside of the JAXB spec (these extension classes reside in the com.sun.xml.bind package).
This document will outline the design for an EclipseLink equivalent to this extension.
