Convert Encoding : Encoding « I18N « Java

1. Java
2. I18N
3. Encoding

Convert Encoding

   
/*
 * 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.
 */

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import java.io.Writer;

/** 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.
      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.
  }
}

           
         
    
    
  

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