将 String 解析为 arrayList 元素

Question

我的数据库中有这个字符串：

<user>
    <name>John</name>
    <surname>Shean</surname>
    <birthdate>1/1/1111</birthdate>
    <phone >(555) 444-1111</phone>
    <city>NY</city>
</user>

我需要解析它并添加到：

arrayList<User>.(User(name,surname,...))

最终应该是这样的：

user[1]={name="John",surname="Shena",...}

我使用了以下方法，但它不能正常工作。有没有人有办法做到这一点？

public User parseList(String array) {

    User user = new User();

    try {

        DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();

        URL u = new URL("xmldb:exist://192.168.1.71:8094/exist/xmlrpc/db/testDB/userInformation.xml");

        Document doc = builder.parse(u.openStream());

        NodeList nodes = doc.getElementsByTagName("user");

            Element element = (Element) nodes.item(0);

            user.setName(getElementValue(element, "name"));
            user.setSurname(getElementValue(element, "surname"));
            user.setBirthdate(getElementValue(element, "birthdate"));
            user.setPhone(getElementValue(element, "phone"));
            user.setCity(getElementValue(element, "city"));

            System.out.println(user);

    } catch (Exception e) {
        e.printStackTrace();
    }
    return user;
}

protected String getElementValue(Element parent, String label) {
    return getCharacterDataFromElement((Element) parent.getElementsByTagName(label).item(0));
}

private String getCharacterDataFromElement(Element e) {
    try {
        Node child = e.getFirstChild();
        if (child instanceof CharacterData) {
            CharacterData cd = (CharacterData) child;
            return cd.getData();
        }
    } catch (Exception ex) {
    }
    return "";
}

Answer 1

如果要解析 XML，可以使用 XML 解析器。 这可能会帮助您： Java:XML Parser

Answer 2

1 - 为您的使用类建模：

package com.howtodoinjava.xml.sax;

/**
 * Model class. Its instances will be populated using SAX parser.
 * */
public class User
{
    //XML attribute id
    private int id;
    //XML element name
    private String Name;
    //XML element surname
    private String SurName;
    //...

    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return Name;
    }
    public void setName(String Name) {
        this.Name = Name;
    }
    public String getSurName() {
        return SurName;
    }
    public void setSurName(String SurName) {
        this.SurName = SurName;
    }

    // [...]

    @Override
    public String toString() {
        return this.id + ":" + this.Name +  ":" +this.SurName ;
    }
}

2 - 通过扩展 DefaultParser 构建处理程序

package com.howtodoinjava.xml.sax;

import java.util.ArrayList;
import java.util.Stack;

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

public class UserParserHandler extends DefaultHandler
{
    //This is the list which shall be populated while parsing the XML.
    private ArrayList userList = new ArrayList();

    //As we read any XML element we will push that in this stack
    private Stack elementStack = new Stack();

    //As we complete one user block in XML, we will push the User instance in userList
    private Stack objectStack = new Stack();

    public void startDocument() throws SAXException
    {
        //System.out.println("start of the document   : ");
    }

    public void endDocument() throws SAXException
    {
        //System.out.println("end of the document document     : ");
    }

    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException
    {
        //Push it in element stack
        this.elementStack.push(qName);

        //If this is start of 'user' element then prepare a new User instance and push it in object stack
        if ("user".equals(qName))
        {
            //New User instance
            User user = new User();

            //Set all required attributes in any XML element here itself
            if(attributes != null && attributes.getLength() == 1)
            {
                user.setId(Integer.parseInt(attributes.getValue(0)));
            }
            this.objectStack.push(user);
        }
    }

    public void endElement(String uri, String localName, String qName) throws SAXException
    {
        //Remove last added  element
        this.elementStack.pop();

        //User instance has been constructed so pop it from object stack and push in userList
        if ("user".equals(qName))
        {
            User object = this.objectStack.pop();
            this.userList.add(object);
        }
    }

    /**
     * This will be called everytime parser encounter a value node
     * */
    public void characters(char[] ch, int start, int length) throws SAXException
    {
        String value = new String(ch, start, length).trim();

        if (value.length() == 0)
        {
            return; // ignore white space
        }

        //handle the value based on to which element it belongs
        if ("name".equals(currentElement()))
        {
            User user = (User) this.objectStack.peek();
            user.setName(value);
        }
        else if ("surname".equals(currentElement()))
        {
            User user = (User) this.objectStack.peek();
            user.setSurName(value);
        }
    }

    /**
     * Utility method for getting the current element in processing
     * */
    private String currentElement()
    {
        return this.elementStack.peek();
    }

    //Accessor for userList object
    public ArrayList getUsers()
    {
        return userList;
    }
}

3 - 为 xml 文件编写解析器

package com.howtodoinjava.xml.sax;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;

import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.XMLReaderFactory;

public class UsersXmlParser
{
    public ArrayList parseXml(InputStream in)
    {
        //Create a empty link of users initially
        ArrayList<user> users = new ArrayList</user><user>();
        try
        {
            //Create default handler instance
            UserParserHandler handler = new UserParserHandler();

            //Create parser from factory
            XMLReader parser = XMLReaderFactory.createXMLReader();

            //Register handler with parser
            parser.setContentHandler(handler);

            //Create an input source from the XML input stream
            InputSource source = new InputSource(in);

            //parse the document
            parser.parse(source);

            //populate the parsed users list in above created empty list; You can return from here also.
            users = handler.getUsers();

        } catch (SAXException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {

        }
        return users;
    }
}

4 - 测试解析器

package com.howtodoinjava.xml.sax;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.ArrayList;

public class TestSaxParser
{
    public static void main(String[] args) throws FileNotFoundException
    {
        //Locate the file OR String
        File xmlFile = new File("D:/temp/sample.xml");

        //Create the parser instance
        UsersXmlParser parser = new UsersXmlParser();

        //Parse the file Or change to parse String
        ArrayList users = parser.parseXml(new FileInputStream(xmlFile));

        //Verify the result
        System.out.println(users);
    }
}