Tuesday, August 13, 2013

mapping XML to Java objects without XSD

There is a common misconception that JAXB requires an XML Schema

Until I read the following blog post, JAXB xjc Java Generation with DTD, I was also thinking that there was no binding solution for DTDs when you try to map XML content into Java objects. 

For that reason, while maintaining some legacy applications using DTD, I was being forced to write my own parser(using SAX generally) for each different XML structure.

Luckily, although not part of the JAXB specification, the XJC tool offers the ability to generate Java classes from a DTD.

Simply execute the following command in your console, 

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"%JAVA_HOME%\bin\xjc" -dtd -d generatedsrc -p the.target.packagename sample.dtd
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-d <dir>  : generated files will go into this directory
-p <pkg>  : specifies the target package
-dtd   : treat input as XML DTD


Sample DTD File : Product Catalog
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<!ENTITY AUTHOR "John Doe">
 
<!ENTITY COMPANY "JD Power Tools, Inc.">
 
<!ENTITY EMAIL "jd@jd-tools.com">
 
 
<!ELEMENT CATALOG (PRODUCT+)>
 
 
<!ELEMENT PRODUCT
 
(SPECIFICATIONS+,OPTIONS?,PRICE+,NOTES?)>
 
<!ATTLIST PRODUCT
 
NAME CDATA #IMPLIED
 
CATEGORY (HandTool|Table|Shop-Professional) "HandTool"
 
PARTNUM CDATA #IMPLIED
 
PLANT (Pittsburgh|Milwaukee|Chicago) "Chicago"
 
INVENTORY (InStock|Backordered|Discontinued) "InStock">
 
 
<!ELEMENT SPECIFICATIONS (#PCDATA)>
 
<!ATTLIST SPECIFICATIONS
 
WEIGHT CDATA #IMPLIED
 
POWER CDATA #IMPLIED>
 
 
<!ELEMENT OPTIONS (#PCDATA)>
 
<!ATTLIST OPTIONS
 
FINISH (Metal|Polished|Matte) "Matte"
 
ADAPTER (Included|Optional|NotApplicable) "Included"
 
CASE (HardShell|Soft|NotApplicable) "HardShell">
 
 
<!ELEMENT PRICE (#PCDATA)>
 
<!ATTLIST PRICE
 
MSRP CDATA #IMPLIED
 
WHOLESALE CDATA #IMPLIED
 
STREET CDATA #IMPLIED
 
SHIPPING CDATA #IMPLIED>
 
 
<!ELEMENT NOTES (#PCDATA)>
Running XJC and producing Java classes
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xjc.exe -dtd -d generatedsrc -p com.example.product.catalog product_catalog.dtd
parsing a schema...
compiling a schema...
com\example\product\catalog\CATALOG.java
com\example\product\catalog\OPTIONS.java
com\example\product\catalog\ObjectFactory.java
com\example\product\catalog\PRICE.java
com\example\product\catalog\PRODUCT.java
com\example\product\catalog\SPECIFICATIONS.java
Product.java
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//
// This file was generated by the JavaTM Architecture for XML Binding(JAXB) Reference Implementation, vJAXB 2.1.10 in JDK 6
// Any modifications to this file will be lost upon recompilation of the source schema.
// Generated on: 2013.11.02 at 02:15:25 PM VET
//
 
 
package com.example.product.catalog;
 
import java.util.ArrayList;
import java.util.List;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;
import javax.xml.bind.annotation.adapters.CollapsedStringAdapter;
import javax.xml.bind.annotation.adapters.NormalizedStringAdapter;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
 
 
/**
 *
 */
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "", propOrder = {
    "specifications",
    "options",
    "price",
    "notes"
})
@XmlRootElement(name = "PRODUCT")
public class PRODUCT {
 
    @XmlAttribute(name = "NAME")
    @XmlJavaTypeAdapter(NormalizedStringAdapter.class)
    protected String name;
    @XmlAttribute(name = "CATEGORY")
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    protected String category;
    @XmlAttribute(name = "PARTNUM")
    @XmlJavaTypeAdapter(NormalizedStringAdapter.class)
    protected String partnum;
    @XmlAttribute(name = "PLANT")
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    protected String plant;
    @XmlAttribute(name = "INVENTORY")
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    protected String inventory;
    @XmlElement(name = "SPECIFICATIONS", required = true)
    protected List<SPECIFICATIONS> specifications;
    @XmlElement(name = "OPTIONS")
    protected OPTIONS options;
    @XmlElement(name = "PRICE", required = true)
    protected List<PRICE> price;
    @XmlElement(name = "NOTES")
    protected String notes;
 
    /**
     * Gets the value of the name property.
     *
     * @return
     *     possible object is
     *     {@link String }
     *    
     */
    public String getNAME() {
        return name;
    }
 
    /**
     * Sets the value of the name property.
     *
     * @param value
     *     allowed object is
     *     {@link String }
     *    
     */
    public void setNAME(String value) {
        this.name = value;
    }
 
    /**
     * Gets the value of the category property.
     *
     * @return
     *     possible object is
     *     {@link String }
     *    
     */
    public String getCATEGORY() {
        if (category == null) {
            return "HandTool";
        } else {
            return category;
        }
    }
 
    /**
     * Sets the value of the category property.
     *
     * @param value
     *     allowed object is
     *     {@link String }
     *    
     */
    public void setCATEGORY(String value) {
        this.category = value;
    }
 
    /**
     * Gets the value of the partnum property.
     *
     * @return
     *     possible object is
     *     {@link String }
     *    
     */
    public String getPARTNUM() {
        return partnum;
    }
 
    /**
     * Sets the value of the partnum property.
     *
     * @param value
     *     allowed object is
     *     {@link String }
     *    
     */
    public void setPARTNUM(String value) {
        this.partnum = value;
    }
 
    /**
     * Gets the value of the plant property.
     *
     * @return
     *     possible object is
     *     {@link String }
     *    
     */
    public String getPLANT() {
        if (plant == null) {
            return "Chicago";
        } else {
            return plant;
        }
    }
 
    /**
     * Sets the value of the plant property.
     *
     * @param value
     *     allowed object is
     *     {@link String }
     *    
     */
    public void setPLANT(String value) {
        this.plant = value;
    }
 
    /**
     * Gets the value of the inventory property.
     *
     * @return
     *     possible object is
     *     {@link String }
     *    
     */
    public String getINVENTORY() {
        if (inventory == null) {
            return "InStock";
        } else {
            return inventory;
        }
    }
 
    /**
     * Sets the value of the inventory property.
     *
     * @param value
     *     allowed object is
     *     {@link String }
     *    
     */
    public void setINVENTORY(String value) {
        this.inventory = value;
    }
 
    /**
     * Gets the value of the specifications property.
     *
     * <p>
     * This accessor method returns a reference to the live list,
     * not a snapshot. Therefore any modification you make to the
     * returned list will be present inside the JAXB object.
     * This is why there is not a <CODE>set</CODE> method for the specifications property.
     *
     * <p>
     * For example, to add a new item, do as follows:
     * <pre>
     *    getSPECIFICATIONS().add(newItem);
     * </pre>
     *
     *
     * <p>
     * Objects of the following type(s) are allowed in the list
     * {@link SPECIFICATIONS }
     *
     *
     */
    public List<SPECIFICATIONS> getSPECIFICATIONS() {
        if (specifications == null) {
            specifications = new ArrayList<SPECIFICATIONS>();
        }
        return this.specifications;
    }
 
    /**
     * Gets the value of the options property.
     *
     * @return
     *     possible object is
     *     {@link OPTIONS }
     *    
     */
    public OPTIONS getOPTIONS() {
        return options;
    }
 
    /**
     * Sets the value of the options property.
     *
     * @param value
     *     allowed object is
     *     {@link OPTIONS }
     *    
     */
    public void setOPTIONS(OPTIONS value) {
        this.options = value;
    }
 
    /**
     * Gets the value of the price property.
     *
     * <p>
     * This accessor method returns a reference to the live list,
     * not a snapshot. Therefore any modification you make to the
     * returned list will be present inside the JAXB object.
     * This is why there is not a <CODE>set</CODE> method for the price property.
     *
     * <p>
     * For example, to add a new item, do as follows:
     * <pre>
     *    getPRICE().add(newItem);
     * </pre>
     *
     *
     * <p>
     * Objects of the following type(s) are allowed in the list
     * {@link PRICE }
     *
     *
     */
    public List<PRICE> getPRICE() {
        if (price == null) {
            price = new ArrayList<PRICE>();
        }
        return this.price;
    }
 
    /**
     * Gets the value of the notes property.
     *
     * @return
     *     possible object is
     *     {@link String }
     *    
     */
    public String getNOTES() {
        return notes;
    }
 
    /**
     * Sets the value of the notes property.
     *
     * @param value
     *     allowed object is
     *     {@link String }
     *    
     */
    public void setNOTES(String value) {
        this.notes = value;
    }
 
}