Oracle Text Indexing - escaping user input

Here's a class passed to me for escaping keywords and dealing with how to pass user input to Oracle's text indexing functions. In particular the CONTAINS operator.

// from oracle web site.
package foo;

import java.util.Vector;

/**
 * Escapes search phrases so they can be safely passed to Oracle's SQL
 * CONTAINS operator.
 * 

 * WARNING: it appears that this class is not thread safe and that
 * it maintains state between calls and thus a new object should be created
 * between each use rather than reusing the same object.
 */
public class QueryTranslator {

  // XXX make thread safe and change so that reqWords and notWords get cleared
  // out.  If that's done this we don't have to create a new instance of this
  // object each time we want to translate something.

  private Vector reqWords = new Vector();

  private Vector notWords = new Vector();

  public String translate(String input) {
    if (input.indexOf('{') > -1 || input.indexOf('}') > -1) {
      throw new IllegalArgumentException("'}' and '{' should not appear in input");
    }
    processString(input);
    if (this.reqWords.size() == 0) {
      throw new IllegalArgumentException("no 'required' words in query: " + input);
    }
    String translatedQuery = getQuery();
    if (translatedQuery.indexOf("()") > -1 
        || translatedQuery.indexOf("{}") > -1
        || translatedQuery.indexOf("\\}") > -1) {
      throw new IllegalArgumentException("can't construct a valid oracle text query from: " + input);
    }
    return translatedQuery;
  }

  private void addWord(final String word, final boolean isRequired) {

    if (isRequired) {
      this.reqWords.add(word);
    } else {
      this.notWords.add(word);
    }
  }

  public void processString(final String input) {
    int p = 0;
    int startWord;
    String theWord;

    this.reqWords = new Vector();
    this.notWords = new Vector();

    while (true) { // Loop over all words

      startWord = p;
      while (p < input.length() && input.charAt(p) != ' ') {
        // Check for quoted phrase
        if (input.charAt(p) == '"') { // Quote - skip to next or end
          p++; // skip the actual quote
          while (p < input.length() && input.charAt(p) != '"') {
            p++;
          }
          if (p < input.length()) {
            p++; // Skip the final quote if found
          }
        } else {
          p++;
        }
      }

      // Got a word. Check for required/not wanted flags (+-)

      theWord = input.substring(startWord, p);

      // CY bug 11825, don't process zero length string
      if (theWord.length() > 0) {
        // CY changed this to required from optional to make it AND
        // logic
        boolean isRequired = true;

        if (theWord.charAt(0) == '+' && theWord.length() > 1) {
          isRequired = true;
          theWord = theWord.substring(1);
        }

        else if (theWord.charAt(0) == '-' && theWord.length() > 1) {
          isRequired = false;
          theWord = theWord.substring(1);
        }

        // Replace * wild cards with %

        theWord = theWord.replace('*', '%');

        if (!"%".equals(theWord)) {
          addWord(theWord, isRequired);
        }

      }
      p++;
      if (p >= input.length()) {
        break;
      }
    }
  }

  // Get word gets a single word from the "words" vector,
  // surrounds it in braces (to avoid reserved words)
  // and attaches a WITHIN clause if appropriate.

  private String getWord(final Vector words, final int pos) {
    // here I added stuff for handling the wildcard, which doesn't work if
    // in {}
    String word = words.elementAt(pos);
    if (word.indexOf('%') > -1) {
      word =  word.replaceAll("[\\W&&[^%]]", "");
      if ("%".equals(word)) {
        return "";
      }
      return word;
    }
    if (word.lastIndexOf('\\') == word.length() - 1) {
      word = word.substring(0, word.length() - 1);
    }
    return "${".concat( word) + '}';
  }

  // getQuery returns a formatted, ready-to-run ConText query.
  // In order to satisfy the altavista syntax, we have to generate
  // the following query:

  // ( req1 & req2 & ... reqN)
  // | ( (req1 & req2 & .. reqN)*10*10
  // & (req1, req2 , ... reqN , opt1 , opt2 , ... optN) )
  // NOT (not1 | not2 | ... notN)

  public String getQuery() {
    StringBuffer sb = new StringBuffer();
    // String tempString = "";

    String boolOp = ""; // AND, OR, NOT operator
    int reqCount; // Count of required words
    int notCount; // Count of not wanted words
    int i; // Loop control

    boolOp = "";
    reqCount = this.reqWords.size();
    notCount = this.notWords.size();

    if (this.reqWords.size() > 0) {
      // Required words - first time

      sb.append("((");
      for (i = 0; i < reqCount; i++) {
        sb.append(boolOp).append(getWord(this.reqWords, i));
        boolOp = " & ";
      }
    }

    if (reqCount > 0) {
      sb.append(")) ");
    }

    if (notCount > 0) {
      boolOp = " NOT ";
    } else {
      boolOp = "";
    }

    for (i = 0; i < notCount; i++) {
      sb.append(boolOp).append(getWord(this.notWords, i));
      boolOp = " NOT ";
    }
    return sb.toString();
  }

  public static void main(String args[]) {

    if (args.length != 1) {
      System.out.println("java " + QueryTranslator.class.getName()
          + " search_phrase");
      System.exit(1);
    }

    System.out.println("Orginal Phrase:    " + args[0]);
    System.out.println("Translated Phrase: "
        + new QueryTranslator().translate(args[0]));
  }
}

Aggregation of Social Content

This is an interesting article on aggregation of others' content.

http://www.web-strategist.com/blog/2009/03/24/breakdown-twitter-federated-media-and-microsofts-sponsored-aggregation/

RequestDispatcher

I've been running into some strange behavior in legacy code dealing with how RequestDispatcher objects are gotten when the incoming URL has invalid characters in the query string portion of the URL. This page didn't help much, but it was interesting reading.

http://www.roseindia.net/javacertification/wcd-guide/machanism.shtml

My problem seems to be caused by crawlers my parsing our pages and not properly unescaping XHTML entities such as & that they encounter in links or image URLs.