Android File Encode Guess guessEncoding(File file)

Description

Try to guess the file encoding.

License

Apache License

Parameter

Parameter	Description
file	The file needed to guess the encoding.

Exception

Parameter	Description
IOException	an exception

Return

The encoding, may be null.

Declaration

public static String guessEncoding(File file) throws IOException 

Method Source Code

/**/*from  w w w .ja  va  2s.  co  m*/
 *  Copyright 2009 Welocalize, Inc. 
 *  
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  
 *  You may obtain a copy of the License at 
 *  http://www.apache.org/licenses/LICENSE-2.0
 *  
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *  
 */

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileFilter;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.log4j.Logger;

public class Main{
    static public final String UTF8 = "UTF-8";
    static public final String UTF16LE = "UTF-16LE";
    static public final String UTF16BE = "UTF-16BE";
    /**
     * Try to guess the file encoding.
     * <p>
     * 
     * Only guees encodings of "UTF-8", "UTF-16" or "UTF-16BE".
     * 
     * @param file
     *            The file needed to guess the encoding.
     * @return The encoding, may be null.
     * @throws IOException
     */
    public static String guessEncoding(File file) throws IOException {
        byte[] b = readFile(file, 3);
        String guess = null;

        if (b[0] == (byte) 0xef && b[1] == (byte) 0xbb
                && b[2] == (byte) 0xbf)
            guess = UTF8;
        else if (b[0] == (byte) 0xff && b[1] == (byte) 0xfe)
            guess = UTF16LE;
        else if (b[0] == (byte) 0xfe && b[1] == (byte) 0xff)
            guess = UTF16BE;

        return guess;
    }
    public static byte[] readFile(File file, int size) throws IOException {
        return readFile(new FileInputStream(file), size);
    }
    /**
     * Reads bytes from given input stream with specified length.
     */
    public static byte[] readFile(InputStream in, int size)
            throws IOException {
        byte[] b = new byte[size];
        try {
            in.read(b, 0, size);
        } finally {
            if (in != null) {
                in.close();
            }
        }

        return b;
    }
    public static String readFile(File file) throws IOException {
        FileInputStream in = null;

        try {
            in = new FileInputStream(file);
            byte[] b = new byte[in.available()];
            in.read(b, 0, b.length);
            return new String(b);
        } finally {
            if (in != null) {
                in.close();
            }
        }
    }
    public static String readFile(File file, String encoding)
            throws IOException {
        return readFile(new FileInputStream(file), encoding);
    }
    /**
     * Reads the given input stream to a string content.
     */
    public static String readFile(InputStream in, String encoding)
            throws IOException {
        try {
            byte[] b = new byte[in.available()];
            in.read(b);
            return new String(b, encoding);
        } finally {
            if (in != null) {
                in.close();
            }
        }
    }
}

Related

1. guessEncoding(File file)
2. guessEncoding(InputStream inputStream)
3. getEncodingOfXml(File file)