SAX的使用方法简介(三)

SAX的使用方法简介(三)

      用SAX来写入XML文件，程序的目标是在上一节的XML文件中，在每一个<senator>节点的最下面插入一个节点<elected>2004</elected>，并用new.xml把文件存下来。

请看源程序：

import java.io.*;
import org.xml.sax.*;
import javax.xml.parsers.*;
import org.xml.sax.helpers.DefaultHandler;

public class ch17_07 extends DefaultHandler
{
    static String displayText[] = new String[1000];
    static int numberLines = 0;
    static String indentation = "";

    public static void main(String args[])
    {
        ch17_07 obj = new ch17_07();
        obj.childLoop(args[0]);

//和上一个程序一样，我们把XML文件的内容在遍历以后存到数组里面，现在我们把它写到硬盘上
        try {
            FileWriter filewriter = new FileWriter("new.xml");

            for(int loopIndex = 0; loopIndex < numberLines; loopIndex++){
                filewriter.write(displayText[loopIndex].toCharArray());
                filewriter.write('/n');
            }

            filewriter.close();
        }
        catch (Exception e) {
            e.printStackTrace(System.err);
        }
    }

    public void childLoop(String uri)
    {
        DefaultHandler handler = this;
        SAXParserFactory factory = SAXParserFactory.newInstance();
        try {
            SAXParser saxParser = factory.newSAXParser();
            saxParser.parse(new File(uri), handler);
        } catch (Throwable t) {}
    }

    public void startDocument()
    {
        displayText[numberLines] = indentation;
        displayText[numberLines] += ""1.0/" encoding=/""+
            "UTF-8" + "/"?>";
        numberLines++;
    }

    public void processingInstruction(String target, String data)
    {
        displayText[numberLines] = indentation;
        displayText[numberLines] += ";
        displayText[numberLines] += target;
        if (data != null && data.length() > 0) {
            displayText[numberLines] += ' ';
            displayText[numberLines] += data;
        }
        displayText[numberLines] += "?>";
        numberLines++;
    }

    public void startElement(String uri, String localName,
        String qualifiedName, Attributes attributes)
    {
        displayText[numberLines] = indentation;

        indentation += "    ";

        displayText[numberLines] += '<';
        displayText[numberLines] += qualifiedName;
        if (attributes != null) {
            int numberAttributes = attributes.getLength();
            for (int loopIndex = 0; loopIndex < numberAttributes; loopIndex++){
                displayText[numberLines] += ' ';
                displayText[numberLines] += attributes.getQName(loopIndex);
                displayText[numberLines] += "=/"";
                displayText[numberLines] += attributes.getValue(loopIndex);
                displayText[numberLines] += '"';
            }
        }
        displayText[numberLines] += '>';
        numberLines++;
    }

    public void characters(char characters[], int start, int length)
    {
        String characterData = (new String(characters, start, length)).trim();
        if(characterData.indexOf("/n") < 0 && characterData.length() > 0) {
            displayText[numberLines] = indentation;
            displayText[numberLines] += characterData;
            numberLines++;
        }
    }

    public void ignorableWhitespace(char characters[], int start, int length)
    {
        //characters(characters, start, length);
    }

    public void endElement(String uri, String localName, String qualifiedName)
    {
        indentation = indentation.substring(0, indentation.length() - 4) ;
        displayText[numberLines] = indentation;
        displayText[numberLines] += ";
        displayText[numberLines] += qualifiedName;
        displayText[numberLines] += '>';
        numberLines++;

//遇到了我们要增加节点的位置，增加一个节点
        if (qualifiedName.equals("lastName")) {
            startElement("", "elected", "elected", null);
            characters("2004".toCharArray(), 0, "2004".length());
            endElement("", "elected", "elected");
        }
    }

    public void warning(SAXParseException exception)
    {
        System.err.println("Warning: " +
            exception.getMessage());
    }

    public void error(SAXParseException exception)
    {
        System.err.println("Error: " +
            exception.getMessage());
    }

    public void fatalError(SAXParseException exception)
    {
        System.err.println("Fatal error: " +
            exception.getMessage());
    }
}