使用 SAX 解析器，如何解析具有相同名称标签但元

问题描述

是否可以在 SAX 解析器中给出路径表达式?我有一个 XML 文件，它有几个相同的名称标签，但它们在不同的元素中.有什么方法可以区分它们.这是 XML:

Is it possible to give path expressions in SAX parser? I have an XML file which has a few same name tags, but they are in different element. Is there any way to differentiate 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>

我想将学生的姓名和 ID 与学校的名称和 ID 区分开来.

I want to differentiate between the Name and Id of a student from the name and ID of a school.

感谢您的回复:

我创建了一个学生 pojo，它具有以下字段 - school_id、school_name、student_id 和 student_name 以及它们的 getter 和 setter 方法.这是我的临时解析器实现.当我解析 xml 时，我需要将学校名称、id、学生姓名、id 的值放入 pojo 中并返回.你能告诉我我应该如何实现差异化堆栈.这是我的解析器框架::

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

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);

    }
}

推荐答案

好吧，我已经很多年没有在 Java 中使用 SAX 了，所以这是我的看法:

Well, I haven't played in years with SAX in Java, so here's my take on it:

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 包含您的示例 XML.请注意，我将所有内容都塞进了一个文件中，但这只是因为我只是在玩耍.

schools.xml contains your example XML. Please note that I crammed everything in a single file, but this is only for I was just playing around.

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