Java by API/java.io/FilterReader

extends FilterReader

   <source lang="java">
 

/*

* Copyright (c) 2004 David Flanagan.  All rights reserved.
* This code is from the book Java Examples in a Nutshell, 3nd Edition.
* It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
* You may study, use, and modify it for any non-commercial purpose,
* including teaching and use in open-source projects.
* You may distribute it non-commercially as long as you retain this notice.
* For a commercial use license, or to purchase the book, 
* please visit http://www.davidflanagan.ru/javaexamples3.
*/

import java.io.BufferedReader; import java.io.FileReader; import java.io.FilterReader; import java.io.IOException; import java.io.Reader; /**

* A simple FilterReader that strips HTML tags (or anything between pairs of
* angle brackets) out of a stream of characters.
*/

public class RemoveHTMLReader extends FilterReader {

 /** A trivial constructor. Just initialize our superclass */
 public RemoveHTMLReader(Reader in) {
   super(in);
 }
 boolean intag = false; // Used to remember whether we are "inside" a tag
 /**
  * This is the implementation of the no-op read() method of FilterReader. It
  * calls in.read() to get a buffer full of characters, then strips out the
  * HTML tags. (in is a protected field of the superclass).
  */
 public int read(char[] buf, int from, int len) throws IOException {
   int numchars = 0; // how many characters have been read
   // Loop, because we might read a bunch of characters, then strip them
   // all out, leaving us with zero characters to return.
   while (numchars == 0) {
     numchars = in.read(buf, from, len); // Read characters
     if (numchars == -1)
       return -1; // Check for EOF and handle it.
     // Loop through the characters we read, stripping out HTML tags.
     // Characters not in tags are copied over previous tags
     int last = from; // Index of last non-HTML char
     for (int i = from; i < from + numchars; i++) {
       if (!intag) { // If not in an HTML tag
         if (buf[i] == "<")
           intag = true; // check for tag start
         else
           buf[last++] = buf[i]; // and copy the character
       } else if (buf[i] == ">")
         intag = false; // check for end of tag
     }
     numchars = last - from; // Figure out how many characters remain
   } // And if it is more than zero characters
   return numchars; // Then return that number.
 }
 /**
  * This is another no-op read() method we have to implement. We implement it
  * in terms of the method above. Our superclass implements the remaining
  * read() methods in terms of these two.
  */
 public int read() throws IOException {
   char[] buf = new char[1];
   int result = read(buf, 0, 1);
   if (result == -1)
     return -1;
   else
     return (int) buf[0];
 }
 /** The test program: read a text file, strip HTML, print to console */
 public static void main(String[] args) {
   try {
     if (args.length != 1)
       throw new IllegalArgumentException("Wrong number of args");
     // Create a stream to read from the file and strip tags from it
     BufferedReader in = new BufferedReader(new RemoveHTMLReader(new FileReader(args[0])));
     // Read line by line, printing lines to the console
     String line;
     while ((line = in.readLine()) != null)
       System.out.println(line);
     in.close(); // Close the stream.
   } catch (Exception e) {
     System.err.println(e);
     System.err.println("Usage: java RemoveHTMLReader$Test" + " <filename>");
   }
 }

}

 </source>
   
  
 
  

new FileReader(File file)

   <source lang="java">

import java.io.File; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; public class Main {

 public static void main(String[] args) throws IOException {
   File inputFile = new File("farrago.txt");
   File outputFile = new File("outagain.txt");
   FileReader in = new FileReader(inputFile);
   FileWriter out = new FileWriter(outputFile);
   int c;
   while ((c = in.read()) != -1)
     out.write(c);
   in.close();
   out.close();
 }

}

 </source>