/* * Copyright (c) 2000 David Flanagan.  All rights reserved. * This code is from the book Java Examples in a Nutshell, 2nd 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. * You may distribute it non-commercially as long as you retain this notice. * For a commercial use license, or to purchase the book (recommended), * visit http://www.davidflanagan.com/javaexamples2. */package com.davidflanagan.examples.i18n;import java.io.*;/** A program to convert from one character encoding to another */public class ConvertEncoding {    public static void main(String[] args) {        String from = null, to = null;        String infile = null, outfile = null;        for(int i = 0; i < args.length; i++) { // Parse command-line arguments.            if (i == args.length-1) usage();   // All args require another.            if (args[i].equals("-from")) from = args[++i];            else if (args[i].equals("-to")) to = args[++i];            else if (args[i].equals("-in")) infile = args[++i];            else if (args[i].equals("-out")) outfile = args[++i];            else usage();        }        try { convert(infile, outfile, from, to); }  // Attempt conversion.        catch (Exception e) {                        // Handle exceptions.            LocalizedError.display(e);  // Defined at the end of this chapter.            System.exit(1);        }    }    public static void usage() {        System.err.println("Usage: java ConvertEncoding <options>\n" +			   "Options:\n\t-from <encoding>\n\t" + 			   "-to <encoding>\n\t" +			   "-in <file>\n\t-out <file>");        System.exit(1);    }    public static void convert(String infile, String outfile,			       String from, String to)              throws IOException, UnsupportedEncodingException    {        // Set up byte streams.        InputStream in;        if (infile != null) in = new FileInputStream(infile);        else in = System.in;        OutputStream out;        if (outfile != null) out = new FileOutputStream(outfile);        else out = System.out;	        // Use default encoding if no encoding is specified.        if (from == null) from = System.getProperty("file.encoding");        if (to == null) to = System.getProperty("file.encoding");	        // Set up character streams.        Reader r = new BufferedReader(new InputStreamReader(in, from));        Writer w = new BufferedWriter(new OutputStreamWriter(out, to));	        // Copy characters from input to output.  The InputStreamReader        // converts from the input encoding to Unicode, and the        // OutputStreamWriter converts from Unicode to the output encoding.        // Characters that cannot be represented in the output encoding are        // output as '?'        char[] buffer = new char[4096];        int len;        while((len = r.read(buffer)) != -1)  // Read a block of input.            w.write(buffer, 0, len);         // And write it out.        r.close();                           // Close the input.        w.close();                           // Flush and close output.    }}