Generating html links from plain text

Question

How can I scan a text (a String) and add links when a word is an URL?
I tried the following which works but it's too slow:
  String text = rs.getString("text");         
                text2scan=text.split("[\n ]")
                for(int i = 0; i < text2scan.length; i++){
                    String replacement = null;
                    String word = text2scan;
log.info(word);
if(word.indexOf(".com")!=-1){
replacement="<a href=\""+word+"\">"+word+"</a>";
text=text.replaceAll(word, replacement);
text=text.replaceAll("www","http://www");
text=text.replaceAll("http://http://","http://");
text=text.replaceAll(">http://",">");
Isn't this already implemented somewhere?
Thanks
Niklas

Answer 1

Because I was semi interested by this issue, and how best to solve it, heres a quick and dirty example program.
It does a very basic job, but should be pretty much equivalent to what you had originally.
package mypackage;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class RegexpMakeHyperlinks {
      * Loads a file into a StringBuffer
      * @param f File to read
      * @return StringBuffer with contents of text file.
      * @throws IOException
     public StringBuffer loadFile(File f) throws IOException {
        System.out.println("Reading file " + f.getAbsolutePath());
          BufferedReader in = new BufferedReader(new FileReader(f));
          StringWriter sw = new StringWriter();
          PrintWriter pw = new PrintWriter(new BufferedWriter(sw));
          String line = null;
          while ((line = in.readLine()) != null) {
               pw.println(line);
          pw.flush();
          in.close();
          return sw.getBuffer();
      * Writes the contents of a StringBuffer to file
      * @param f File to write to
      * @param sb Text to write to file
      * @throws IOException
     public void writeToFile(File f, StringBuffer sb) throws IOException{
          System.out.println("Outputting to " + f.getAbsolutePath());
          BufferedReader in = new BufferedReader(new StringReader(sb.toString()));
          PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter(f)));
          String line = null;
          while ((line = in.readLine()) != null) {
               out.println(line);
          out.flush();
          in.close();     
      * Converts all urls like "www.google.com" into hyperlinks in the text.
      * @param initialText The text to convert
      * @return Converted text.
     public StringBuffer convertText(StringBuffer initialText) {
          StringBuffer result = new StringBuffer(initialText.length());          
          Pattern p = Pattern.compile("(href=\")?(http://)?www\\..*?.com\\b");
          Matcher m = p.matcher(initialText);
          while (m.find()) {
               String href = m.group();
               // ignore links that are already hyperlinks
               if (href.startsWith("href")){
                    continue;
               // add on the http:// if necessary
               if (!href.startsWith("http://")) {
                    href = "http://" + href;
               // add the new text into the output.
               m.appendReplacement(result, "<a href=\"" + href + "\">" + href + "</a>");
          m.appendTail(result);
          return result;
      * Testing method for experimenting with the patternmatching
      * @param text
     public void matchLink(String text) {
          System.out.println("Analyzing text " + text);
          Pattern p = Pattern.compile("(http://)?www\\..*?.com\\b");
          Matcher m = p.matcher(text);
          while (m.find()) {
               System.out.println("Found: " + m.group());
     public static void main(String[] args) {
          RegexpMakeHyperlinks hyper = new RegexpMakeHyperlinks();
          String[] testStrings = { "www.google.com", "www.myspace.net", "make sure you visit www.yahoo.com for details", "Two sites: http://www.java.com and http://www.javabeans.com" };
          for (int i = 0; i < testStrings.length; i++) {
               hyper.matchLink(testStrings);               
          System.out.println();
          System.out.println("----------------------------");
System.out.println();
File inFile = new File("makeHyperlinkTest.txt");
File outFile = new File("makeHyperlinkTest.output");
try{
StringBuffer sb = hyper.loadFile(inFile);
StringBuffer result = hyper.convertText(sb);
hyper.writeToFile(outFile, result);
catch(Exception e){
     System.out.println("Error " + e.getMessage());
     e.printStackTrace(System.out);      
And a test file makeHyperlinkTest.txt
This file just contains plain text with hyperlinks to places like www.google.com and http://www.yahoo.com.
The program I have written will convert these links like www.google.com into hyperlinks for displaying as html.
Make sure you visit http://www.java.sun.com and read all about Java.
And if I already have an <a href="www.google.com">Hyperlink</a> in this file it should leave it alone right?