Mega Code Archive
Convert Encoding
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/*
* 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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