Java BufferedReader Create createBufferedReader( InputStream inputStream, String strCodepage)

Description

create Buffered Reader

License

LGPL

Declaration

public static BufferedReader createBufferedReader(
            InputStream inputStream, String strCodepage)
            throws UnsupportedEncodingException 

Method Source Code

//package com.java2s;
//License from project: LGPL 

import java.io.*;

import javax.swing.JOptionPane;

import java.awt.Component;

public class Main {
    private static String WARNING = "[!]";
    private static String WARN_ENCODING = "[!]";
    private static boolean s_bWasUtf8Reader = false;

    public static BufferedReader createBufferedReader(
            InputStream inputStream, String strCodepage)
            throws UnsupportedEncodingException {
        return createBufferedReader(inputStream, strCodepage, false, null);
    }/*from w ww .j  a v  a  2s  .c o m*/

    /**
     * @returns a BufferedReader from the given InputStream. Additionally if
     *          a codepage string is given the Reader does the corresponding conversion;
     *          if no codepage is given the default one (Windows) or 1252 (Linux)
     *          is used.
     *          If the given encoding is not supported and a parent component is given
     *          a warning message will be displayed.
     */
    public static BufferedReader createBufferedReader(
            InputStream inputStream, String strCodepage,
            boolean bShowWarning, Component parentComponent)
            throws UnsupportedEncodingException {
        s_bWasUtf8Reader = false;

        InputStream inInternal = inputStream;
        try {
            // if the file has an utf-8 bom then strCodepage is overwritten
            //
            BufferedInputStream bis = new BufferedInputStream(inputStream);
            bis.mark(3);

            byte[] aBom = new byte[3];
            int iRead = bis.read(aBom);

            if (iRead > 0) {
                if (iRead == 3 && (aBom[0] & 0xff) == 0xef
                        && (aBom[1] & 0xff) == 0xbb
                        && (aBom[2] & 0xff) == 0xbf)
                    strCodepage = "utf-8";
                else
                    bis.reset();
            }

            inInternal = bis;
        } catch (IOException exc) {
            exc.printStackTrace();
            // severe error, but it will also happen elsewhere and be handled there
        }

        InputStreamReader isr = null;
        try {
            if (strCodepage != null
                    && (strCodepage.startsWith("Cp")
                            || strCodepage.startsWith("utf") || strCodepage
                                .startsWith("UTF"))) {
                isr = new InputStreamReader(inInternal, strCodepage);
            } else {
                // prior to 1.7.0.p3 there is no CODEPAGE tag
                boolean bIsWindows = File.separator.equals("\\");

                if (bIsWindows)
                    isr = new InputStreamReader(inInternal);
                else
                    isr = new InputStreamReader(inInternal, "Cp1252"); // otherwise defaults to "utf-8" with linux
            }
        } catch (UnsupportedEncodingException exc) {
            exc.printStackTrace();
            isr = new InputStreamReader(inInternal, "ISO8859_1");
        }

        if (strCodepage != null && bShowWarning) {
            String strEncoding = isr.getEncoding();
            if (!EqualsEncodings(strEncoding, strCodepage)) {
                JOptionPane
                        .showMessageDialog(parentComponent, WARN_ENCODING,
                                WARNING, JOptionPane.WARNING_MESSAGE);
            }
        }

        if (IsUtf8Encoding(isr.getEncoding()))
            s_bWasUtf8Reader = true;
        else
            s_bWasUtf8Reader = false;

        return new BufferedReader(isr);
    }

    private static boolean EqualsEncodings(String strEncoding1,
            String strEncoding2) {
        strEncoding1 = strEncoding1.toLowerCase();
        strEncoding2 = strEncoding2.toLowerCase();

        if (strEncoding1.equals(strEncoding2))
            return true;
        else {
            if (strEncoding1.startsWith("utf")
                    && strEncoding2.startsWith("utf")) {
                // remove the first "-" in the strings

                if (strEncoding1.indexOf('-') > -1)
                    strEncoding1 = strEncoding1.substring(0,
                            strEncoding1.indexOf('-'))
                            + strEncoding1.substring(strEncoding2
                                    .indexOf('-') + 1);
                if (strEncoding2.indexOf('-') > -1)
                    strEncoding2 = strEncoding2.substring(0,
                            strEncoding2.indexOf('-'))
                            + strEncoding2.substring(strEncoding2
                                    .indexOf('-') + 1);

                if (strEncoding1.equals(strEncoding2))
                    return true;
            }
        }

        return false;
    }

    private static boolean IsUtf8Encoding(String strEncoding) {
        strEncoding = strEncoding.toLowerCase();

        if (strEncoding.equals("utf8") || strEncoding.equals("utf-8"))
            return true;
        else
            return false;
    }
}

Related

1. getBufferedReader(File file)
2. getBufferedReader(File file)
3. getBufferedReader(File file, String charset)
4. getBufferedReader(File file, String encoding)