java - Android Xml 处理程序仅保留我的 xml 文件中的最后一个对象

Question

我有一个名为 ExampleHandler 扩展自 DefaultHandler 的类。

此类从外部 xml 文件(在网络上)读取数据，该 xml 文件的结构为:

<resultsSet>
    <result>
        <title>WinRANI Web Services!</title>
        <nom>DADI</nom>
        <prenom>Morad</prenom>
        <adresse>DANS MES REVES</adresse>
    </result>
...
</resultsSet>

我创建了一个与此 xml 文件具有相同结构的类，名为 ParsedExampleDataSet(它具有 getter 和 setter)。

我还创建了一个ArrayList，它将包含所有“结果”对象，但问题是当处理程序读取所有对象时，ArrayList中的所有项目> 是一样的。

这是我的代码:

package com.example.helloandroid;

import java.util.ArrayList;

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

import android.util.Log;


public class ExampleHandler extends DefaultHandler{

    // ===========================================================
    // Fields
    // ===========================================================

    private boolean in_resultset = false;
    private boolean in_result = false;
    private boolean in_title = false;
    private boolean in_nom = false;
    private boolean in_prenom = false;
    private boolean in_adresse = false;
    private boolean in_tel = false;
    private boolean in_fax = false;
    private boolean in_lon = false;
    private boolean in_lat = false;
    private boolean in_description = false;
    private boolean in_infos = false;

    private test t;
    private int currentIndex = 0;
    ParsedExampleDataSet[] p = new ParsedExampleDataSet[5];

    private ArrayList<ParsedExampleDataSet> myParsedExampleDataSetList = new ArrayList<ParsedExampleDataSet>();
    private ParsedExampleDataSet myParsedExampleDataSet = new ParsedExampleDataSet();

    private ParsedExampleDataSet s1;
    private ParsedExampleDataSet s2;
    private ParsedExampleDataSet s3;
    private ParsedExampleDataSet s4;
    private ParsedExampleDataSet s5;


    // ===========================================================
    // Getter & Setter
    // ===========================================================

    public ArrayList<ParsedExampleDataSet> getParsedData() {
            return this.myParsedExampleDataSetList;
    }

    // ===========================================================
    // Methods
    // ===========================================================
    @Override
    public void startDocument() throws SAXException {
            this.myParsedExampleDataSet = new ParsedExampleDataSet();
    }

    @Override
    public void endDocument() throws SAXException {
            // Nothing to do
    }

    /** Gets be called on opening tags like:
     * <tag>
     * Can provide attribute(s), when xml was like:
     * <tag attribute="attributeValue">*/
    @Override
    public void startElement(String namespaceURI, String localName,
                    String qName, Attributes atts) throws SAXException {
            if (localName.equals("resultset")) {
                    this.in_resultset = true;
            }else if (localName.equals("result")) {
                    this.in_result = true;
            }else if (localName.equals("title")) {
                    this.in_title = true;
            }else if (localName.equals("nom")) {
                    // Extract an Attribute
                    //String attrValue = atts.getValue("thenumber");
                    //int i = Integer.parseInt(attrValue);
                    //myParsedExampleDataSet.setExtractedInt(i);
                    this.in_nom = true;
            }else if (localName.equals("prenom")) {
                    this.in_prenom = true;
            }else if (localName.equals("tel")) {
                    this.in_tel = true;
            }else if (localName.equals("fax")) {
                    this.in_fax = true;
            }else if (localName.equals("lon")) {
                    this.in_lon = true;
            }else if (localName.equals("lat")) {
                    this.in_lat = true;
            }else if (localName.equals("description")) {
                    this.in_description = true;
            }else if (localName.equals("infos")) {
                    this.in_infos = true;
            }
    }

    /** Gets be called on closing tags like:
     * </tag> */
    @Override
    public void endElement(String namespaceURI, String localName, String qName)
                    throws SAXException {
            if (localName.equals("resultset")) {
                    this.in_resultset = false;

            }else if (localName.equals("result")) {

                    this.in_result = false;
                    myParsedExampleDataSetList.add(myParsedExampleDataSet);

            }else if (localName.equals("title")) {
                    this.in_title = false;
            }else if (localName.equals("nom")) {
                    // Nothing to do here
                    this.in_nom = false;
            }else if (localName.equals("prenom")) {
                    this.in_prenom = false;
            }else if (localName.equals("tel")) {
                    this.in_tel = false;
            }else if (localName.equals("fax")) {
                    this.in_fax = false;
            }else if (localName.equals("lon")) {
                    this.in_lon = false;
            }else if (localName.equals("lat")) {
                    this.in_lat = false;
            }else if (localName.equals("description")) {
                    this.in_description = false;
            }else if (localName.equals("infos")) {
                    this.in_infos = false;
        }
    }

    /** Gets be called on the following structure:
     * <tag>characters</tag> */
    @Override
public void characters(char ch[], int start, int length) {
            if(this.in_title){
            myParsedExampleDataSet.setExtractedTitle(new String(ch, start, length));
    }else if (this.in_nom){
            myParsedExampleDataSet.setExtractedNom(new String(ch,start, length));
    }else if (this.in_prenom){
            myParsedExampleDataSet.setExtractedPrenom(new String(ch,start, length));
    }else if (this.in_tel){
            myParsedExampleDataSet.setExtractedTel(new String(ch,start, length));
    }else if (this.in_fax){
            myParsedExampleDataSet.setExtractedFax(new String(ch,start, length));
    }else if (this.in_lon){
            myParsedExampleDataSet.setExtractedLon(new String(ch,start, length));
    }else if (this.in_lat){
            myParsedExampleDataSet.setExtractedLat(new String(ch,start, length));
    }else if (this.in_description){
            myParsedExampleDataSet.setExtractedDescription(new String(ch,start, length));
    }else if (this.in_infos){
            myParsedExampleDataSet.setExtractedInfos(new String(ch,start, length));
    }

}
}

我的 xml 文件还有一些其他字段。

Answer 1

这是对 Java 的一个常见误解。你必须记住，java 将所有非基元视为指针。在您的情况下，您只需新建一次数据容器对象。因此，当您调用 setter 和 getter 时，您总是会影响多次添加到数组中的同一个对象。

每次向其中添加一组新条目时，您都可以通过新建一个新容器 (ParsedExampleDataSet) 来解决此问题。

else if (localName.equals("结果")) {

   this.in_result = true;
   myParsedExampleDataSet = new ParsedExampleDataSet();

}

还请记住，SAXParser 可以根据字段中的内容对每个字段多次调用characters(..)。因此，您可能希望将从字符获得的值连接到该字段已有的值。

如果(this.in_title){

String value = myParsedExampleDataSet.getExtractedTitle();
value += new String(ch, start, length)
myParsedExampleDataSet.setExtractedTitle(value);

}