Using the SAX parser, how do you parse an XML file with name tags, but in different elements?

Question

Is it possible to give path expressions in a SAX parser? I have an XML file with several name tags, but they are in a different element. Is there a way to distinguish between them. Here is the XML:

<Schools>
    <School>
        <ID>335823</ID> 
        <Name>Fairfax High School</Name> 
        <Student>
            <ID>4195653</ID>
            <Name>Will Turner</Name>
        </Student>
        <Student>
            <ID>4195654</ID>
            <Name>Bruce Paltrow</Name>
        </Student>
        <Student>
            <ID>4195655</ID>
            <Name>Santosh Gowswami</Name>
        </Student>
    </School>
    <School>
        <ID>335824</ID> 
        <Name>FallsChurch High School</Name> 
        <Student>
            <ID>4153</ID>
            <Name>John Singer</Name>
        </Student>
        <Student>
            <ID>4154</ID>
            <Name>Shane Warne</Name>
        </Student>
        <Student>
            <ID>4155</ID>
            <Name>Eddie Diaz</Name>
        </Student>
    </School>
</Schools>

I want to distinguish the name and identifier of the student from the name and identifier of the school.

Thanks for the answer:

I created a student pojo that has the following fields: school_id, school_name, student_id and student_name, as well as the getter and setter methods. This is my temporary implementation of the parser. When I parse the xml, I need to put the values ​​of the school name, id, student name, id in pojo and return it. Can you tell me how I should implement the stack for differentiation. This is my parsing:

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

public class HandleXML extends DefaultHandler {

    private student info;
    private boolean school_id = false;
    private boolean school_name = false;
    private boolean student_id = false;
    private boolean student_name = false;
    private boolean student = false;
    private boolean school = false;


    public HandleXML(student record) {
        super();
        this.info = record;
        school_id = false;
        school_name = false;
        student_id = false;
        student_name = false;
        student = false;
        school = false;
    }

    @Override
    public void startElement(String uri, String localName,
            String qName, Attributes attributes)
            throws SAXException {
    if (qName.equalsIgnoreCase("student")) {
            student = true;
        }
    if (qName.equalsIgnoreCase("school")) {
            school_id = true;
        }
    if (qName.equalsIgnoreCase("school_id")) {
            school_id = true;
        }
    if (qName.equalsIgnoreCase("student_id")) {
            student_id = true;
        }
    if (qName.equalsIgnoreCase("school_name")) {
            school_name = true;
        }
    if (qName.equalsIgnoreCase("student_name")) {
            student_name = true;
        }
    }

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

    @Override
    public void characters(char ch[], int start, int length)
            throws SAXException {

        String data = new String(ch, start, length);

    }
}

Answer 1

, SAX Java, :

package play.xml.sax;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Stack;

public class Test1 {
    public static void main(String[] args) {
        SAXParserFactory spf = SAXParserFactory.newInstance();
        SchoolsHandler handler = new SchoolsHandler();
        try {
            SAXParser sp = spf.newSAXParser();
            sp.parse("schools.xml", handler);
            System.out.println("Number of read schools: " + handler.getSchools().size());
        } catch (SAXException se) {
            se.printStackTrace();
        } catch (ParserConfigurationException pce) {
            pce.printStackTrace();
        } catch (IOException ie) {
            ie.printStackTrace();
        }
    }
}

class SchoolsHandler extends DefaultHandler {
    private static final String TAG_SCHOOLS = "Schools";
    private static final String TAG_SCHOOL = "School";
    private static final String TAG_STUDENT = "Student";
    private static final String TAG_ID = "ID";
    private static final String TAG_NAME = "Name";

    private final Stack<String> tagsStack = new Stack<String>();
    private final StringBuilder tempVal = new StringBuilder();

    private List<School> schools;
    private School school;
    private Student student;

    public void startElement(String uri, String localName, String qName, Attributes attributes) {
        pushTag(qName);
        tempVal.setLength(0);
        if (TAG_SCHOOLS.equalsIgnoreCase(qName)) {
            schools = new ArrayList<School>();
        } else if (TAG_SCHOOL.equalsIgnoreCase(qName)) {
            school = new School();
        } else if (TAG_STUDENT.equalsIgnoreCase(qName)) {
            student = new Student();
        }
    }

    public void characters(char ch[], int start, int length) {
        tempVal.append(ch, start, length);
    }

    public void endElement(String uri, String localName, String qName) {
        String tag = peekTag();
        if (!qName.equals(tag)) {
            throw new InternalError();
        }

        popTag();
        String parentTag = peekTag();

        if (TAG_ID.equalsIgnoreCase(tag)) {
            int id = Integer.valueOf(tempVal.toString().trim());
            if (TAG_STUDENT.equalsIgnoreCase(parentTag)) {
                student.setId(id);
            } else if (TAG_SCHOOL.equalsIgnoreCase(parentTag)) {
                school.setId(id);
            }
        } else if (TAG_NAME.equalsIgnoreCase(tag)) {
            String name = tempVal.toString().trim();
            if (TAG_STUDENT.equalsIgnoreCase(parentTag)) {
                student.setName(name);
            } else if (TAG_SCHOOL.equalsIgnoreCase(parentTag)) {
                school.setName(name);
            }
        } else if (TAG_STUDENT.equalsIgnoreCase(tag)) {
            school.addStudent(student);
        } else if (TAG_SCHOOL.equalsIgnoreCase(tag)) {
            schools.add(school);
        }
    }

    public void startDocument() {
        pushTag("");
    }

    public List<School> getSchools() {
        return schools;
    }

    private void pushTag(String tag) {
        tagsStack.push(tag);
    }

    private String popTag() {
        return tagsStack.pop();
    }

    private String peekTag() {
        return tagsStack.peek();
    }
}

class School {
    private int id;
    private String name;
    private List<Student> students = new ArrayList<Student>();

    public String getName() {
        return name;
    }

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

    public int getId() {
        return id;
    }

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

    public void addStudent(Student student) {
        students.add(student);
    }

    public List<Student> getStudents() {
        return students;
    }
}

class Student {
    private int id;
    private String name;

    public String getName() {
        return name;
    }

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

    public int getId() {
        return id;
    }

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

schools.xml XML. , , , .

Answer 2

SAX . ( startElement endElement). <Name> , .

, , <School> <Student>, , <Name> .

Answer 3

, xml SAX, , , DOM. , / SAX, .

, SAX , .

Answer 4

Sax is event-based, through callbacks you can read an XML document sequentially. Sax is good for reading large XML documents since the entire document does not load into memory. You can look at Xpath , for example

XPathFactory xPathFactory = XPathFactory.newInstance();
XPath xPath = xPathFactory.newXPath();
String expression = "/Schools/school/ ...";
XPathExpression xPathExpression = xPath.compile(expression);
// Compile the expression to get a XPathExpression object.
Object result = xPathExpression.evaluate(xmlDocument);

Answer 5

private boolean isInStudentNode;
...................................................    

public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
    // enter node Student
    if(qName.equalEgnoreCase("Student"){
       isInStudentNode = true;
    }
    ...
}

public void endElement(String uri, String localName, String qName) throws SAXException {
    // end node Student
    if(qName.equalEgnoreCase("Student"){
       isInStudentNode = false;
       ...........
    }

    // end node Name (school|student)
    if(qName.equalEgnoreCase("Name"){
        if(isInStudentNode) student.setName(...);
        else school.setName(...);
    }
}

his work with me