Question

I have an XML document that has HTML tags included:

<chapter>
      <h1>title of content</h1>
      <p> my paragraph ... </p>
 </chapter>

I need to get the content of <chapter> tag and my output will be:

      <h1>title of content</h1>
      <p> my paragraph ... </p>

My question is similar to this post: How parse XML to get one tag and save another tag inside

But I need to implement it in Java using SAX or DOM or …?

I found a soluton using SAX in this post: SAX Parser : Retrieving HTML tags from XML but it’s very buggy and doesn’t work with large amounts of XML data.

Updated:

My SAX implementation:
In some situation it throw exception: java.lang.StringIndexOutOfBoundsException: String index out of range: -4029

public class MyXMLHandler extends DefaultHandler {

private boolean tagFlag = false;

private char[] temp;
String insideTag;
private int startPosition;
private int endPosition;
private String tag;

public void startElement(String uri, String localName, String qName,
        Attributes attributes) throws SAXException {


    if (qName.equalsIgnoreCase(tag)) {
        tagFlag = true;
    }

}

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

    if (qName.equalsIgnoreCase(tag)) {

        insideTag = new String(temp, startPosition, endPosition - startPosition);
        tagFlag = false;
    }

}

public void characters(char ch[], int start, int length)
        throws SAXException {
    temp = ch;
    if (tagFlag) {
        startPosition = start;
        tagFlag = false;
    }
    endPosition = start + length;
}

public String getInsideTag(String tag) {
    this.tag = tag;
    return insideTag;
}

}

Update 2: (Using StringBuilder)

I have accumulated characters by StringBuilder in this way:

public class MyXMLHandler extends DefaultHandler {

private boolean tagFlag = false;

private char[] temp;
String insideTag;
private String tag;
private StringBuilder builder;

public void startElement(String uri, String localName, String qName,
        Attributes attributes) throws SAXException {

    if (qName.equalsIgnoreCase(tag)) {
        builder = new StringBuilder();
        tagFlag = true;
    }

}

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

    if (qName.equalsIgnoreCase(tag)) {
        insideTag = builder.toString();
        tagFlag = false;
    }
}

public void characters(char ch[], int start, int length)
        throws SAXException {
    if (tagFlag) {
        builder.append(ch, start, length);
    }
}

public String getInsideTag(String tag) {
    this.tag = tag;
    return insideTag;
}

}

But builder.append(ch, start, length); doesn’t append Start tag like<EmbeddedTag atr="..."> and </EmbeddedTag> in the Buffer. This Code print Output:

      title of content
      my paragraph ... 

Instead of expected output:

      <h1>title of content</h1>
      <p> my paragraph ... </p>

Update 3:

Finally I have implemented the parser handler:

 public class MyXMLHandler extends DefaultHandler {

private boolean tagFlag = false;
private String insideTag;
private String tag;
private StringBuilder builder;

public void startElement(String uri, String localName, String qName,
        Attributes attributes) throws SAXException {

    if (qName.equalsIgnoreCase(tag)) {
        builder = new StringBuilder();
        tagFlag = true;
    }

    if (tagFlag) {
        builder.append("<" + qName);
         for (int i = 0; i < attributes.getLength(); i++) {
         builder.append(" " + attributes.getLocalName(i) + "=\"" +
         attributes.getValue(i) + "\"");
         }
         builder.append(">");
    }
}

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

    if (tagFlag) {
        builder.append("</" + qName + ">");
    }

    if (qName.equalsIgnoreCase(tag)) {
        insideTag = builder.toString();                     
        tagFlag = false;
    }
    System.out.println("End Element :" + qName);

}

public void characters(char ch[], int start, int length)
        throws SAXException {
    temp = ch;

    if (tagFlag) {
        builder.append(ch, start, length);
    }
}

public String getInsideTag(String tag) {
    this.tag = tag;
    return insideTag;
}

}

Answer 1

The problem with your code is that you try to remember the start and end positions of the string passed to you via the characters method. What you see in the exception thrown is the result of an inside tag that starts near the end of a character buffer and ends near the beginning of the next character buffer.

With sax you need to copy the characters when they are offered or the temporary buffer they occupy might be cleared when you need them.

Your best bet is not to remember the positions in the buffers, but to create a new StringBuilder in startElement and add the characters to that, then get the complete string out the builder in endElement.