Java - Reading XML file

Question

One of the possible implementations:

File file = new File("userdata.xml");
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory
        .newInstance();
DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
Document document = documentBuilder.parse(file);
String usr = document.getElementsByTagName("user").item(0).getTextContent();
String pwd = document.getElementsByTagName("password").item(0).getTextContent();

when used with the XML content:

<credentials>
    <user>testusr</user>
    <password>testpwd</password>
</credentials>

results in "testusr" and "testpwd" getting assigned to the usr and pwd references above.

Reading xml the easy way:

http://www.mkyong.com/java/jaxb-hello-world-example/

package com.mkyong.core;

import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Customer {

    String name;
    int age;
    int id;

    public String getName() {
        return name;
    }

    @XmlElement
    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    @XmlElement
    public void setAge(int age) {
        this.age = age;
    }

    public int getId() {
        return id;
    }

    @XmlAttribute
    public void setId(int id) {
        this.id = id;
    }

} 

.

package com.mkyong.core;

import java.io.File;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;

public class JAXBExample {
    public static void main(String[] args) {

      Customer customer = new Customer();
      customer.setId(100);
      customer.setName("mkyong");
      customer.setAge(29);

      try {

        File file = new File("C:\\file.xml");
        JAXBContext jaxbContext = JAXBContext.newInstance(Customer.class);
        Marshaller jaxbMarshaller = jaxbContext.createMarshaller();

        // output pretty printed
        jaxbMarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

        jaxbMarshaller.marshal(customer, file);
        jaxbMarshaller.marshal(customer, System.out);

          } catch (JAXBException e) {
              e.printStackTrace();
          }

    }
}

If using another library is an option, the following may be easier:

package for_so;

import java.io.File;

import rasmus_torkel.xml_basic.read.TagNode;
import rasmus_torkel.xml_basic.read.XmlReadOptions;
import rasmus_torkel.xml_basic.read.impl.XmlReader;

public class Q7704827_SimpleRead
{
    public static void
    main(String[] args)
    {
        String fileName = args[0];

        TagNode emailNode = XmlReader.xmlFileToRoot(new File(fileName), "EmailSettings", XmlReadOptions.DEFAULT);
        String recipient = emailNode.nextTextFieldE("recipient");
        String sender = emailNode.nextTextFieldE("sender");
        String subject = emailNode.nextTextFieldE("subject");
        String description = emailNode.nextTextFieldE("description");
        emailNode.verifyNoMoreChildren();

        System.out.println("recipient =  " + recipient);
        System.out.println("sender =     " + sender);
        System.out.println("subject =    " + subject);
        System.out.println("desciption = " + description);
    }
}

The library and its documentation are at rasmustorkel.com

Avoid hardcoding try making the code that is dynamic below is the code it will work for any xml I have used SAX Parser you can use dom,xpath it's upto you I am storing all the tags name and values in the map after that it becomes easy to retrieve any values you want I hope this helps
SAMPLE XML:

<parent>
<child >
    <child1> value 1 </child1>
    <child2> value 2 </child2>
    <child3> value 3 </child3>
    </child>
    <child >
     <child4> value 4 </child4>
    <child5> value 5</child5>
    <child6> value 6 </child6>
    </child>
  </parent>

JAVA CODE:

 import java.io.File;
    import java.io.IOException;
    import java.util.HashMap;
    import java.util.LinkedHashMap;
    import java.util.Map;
    import javax.xml.parsers.ParserConfigurationException;
    import javax.xml.parsers.SAXParser;
    import javax.xml.parsers.SAXParserFactory;
    import org.xml.sax.Attributes;
    import org.xml.sax.SAXException;
    import org.xml.sax.helpers.DefaultHandler;


    public class saxParser {
           static Map<String,String> tmpAtrb=null;
           static Map<String,String> xmlVal= new LinkedHashMap<String, String>();
        public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException, VerifyError {

            /**
             * We can pass the class name of the XML parser
             * to the SAXParserFactory.newInstance().
             */

            //SAXParserFactory saxDoc = SAXParserFactory.newInstance("com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl", null);

            SAXParserFactory saxDoc = SAXParserFactory.newInstance();
            SAXParser saxParser = saxDoc.newSAXParser();

            DefaultHandler handler = new DefaultHandler() {
                String tmpElementName = null;
                String tmpElementValue = null;


                @Override
                public void startElement(String uri, String localName, String qName, 
                                                                    Attributes attributes) throws SAXException {
                    tmpElementValue = "";
                    tmpElementName = qName;
                    tmpAtrb=new HashMap();
                    //System.out.println("Start Element :" + qName);
                    /**
                     * Store attributes in HashMap
                     */
                    for (int i=0; i<attributes.getLength(); i++) {
                        String aname = attributes.getLocalName(i);
                        String value = attributes.getValue(i);
                        tmpAtrb.put(aname, value);
                    }

                }

                @Override
                public void endElement(String uri, String localName, String qName) 
                                                            throws SAXException { 

                    if(tmpElementName.equals(qName)){
                        System.out.println("Element Name :"+tmpElementName);
                    /**
                     * Retrive attributes from HashMap
                     */                    for (Map.Entry<String, String> entrySet : tmpAtrb.entrySet()) {
                            System.out.println("Attribute Name :"+ entrySet.getKey() + "Attribute Value :"+ entrySet.getValue());
                        }
                        System.out.println("Element Value :"+tmpElementValue);
                        xmlVal.put(tmpElementName, tmpElementValue);
                        System.out.println(xmlVal);
                      //Fetching The Values From The Map
                        String getKeyValues=xmlVal.get(tmpElementName);
                        System.out.println("XmlTag:"+tmpElementName+":::::"+"ValueFetchedFromTheMap:"+getKeyValues);   
                    }   
                }
                @Override
                public void characters(char ch[], int start, int length) throws SAXException {
                    tmpElementValue = new String(ch, start, length) ;  
                } 
            };
            /**
             * Below two line used if we use SAX 2.0
             * Then last line not needed.
             */

            //saxParser.setContentHandler(handler);
            //saxParser.parse(new InputSource("c:/file.xml"));
            saxParser.parse(new File("D:/Test _ XML/file.xml"), handler);
        }  
    }

OUTPUT:

Element Name :child1
Element Value : value 1 
XmlTag:<child1>:::::ValueFetchedFromTheMap: value 1 
Element Name :child2
Element Value : value 2 
XmlTag:<child2>:::::ValueFetchedFromTheMap: value 2 
Element Name :child3
Element Value : value 3 
XmlTag:<child3>:::::ValueFetchedFromTheMap: value 3 
Element Name :child4
Element Value : value 4 
XmlTag:<child4>:::::ValueFetchedFromTheMap: value 4 
Element Name :child5
Element Value : value 5
XmlTag:<child5>:::::ValueFetchedFromTheMap: value 5
Element Name :child6
Element Value : value 6 
XmlTag:<child6>:::::ValueFetchedFromTheMap: value 6 
Values Inside The Map:{child1= value 1 , child2= value 2 , child3= value 3 , child4= value 4 , child5= value 5, child6= value 6 }