Get string from binary stream. - Java java.io

Java examples for java.io:InputStream Read

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Description

Get string from binary stream.

Demo Code


//package com.java2s;
import java.io.IOException;
import java.io.InputStream;

public class Main {
    /**/*from  w  w w .  j ava2 s . c o  m*/
     * Get string from binary stream. >So, if len < 0x7F, it is encoded on one
     * byte as b0 = len >if len < 0x3FFF, is is encoded on 2 bytes as b0 = (len
     * & 0x7F) | 0x80, b1 = len >> 7 >if len < 0x 1FFFFF, it is encoded on 3
     * bytes as b0 = (len & 0x7F) | 0x80, b1 = ((len >> 7) & 0x7F) | 0x80, b2 =
     * len >> 14 etc.
     *
     * @param is
     * @return
     * @throws IOException
     */
    public static String getString(final InputStream is) throws IOException {
        int val = getStringLength(is);
        //        System.out.println("d:" + val);

        byte[] buffer = new byte[val];
        if (is.read(buffer) < 0) {
            throw new IOException("EOF");
        }
        return new String(buffer);
    }

    /**
     * Binary files are encoded with a variable length prefix that tells you
     * the size of the string. The prefix is encoded in a 7bit format where the
     * 8th bit tells you if you should continue. If the 8th bit is set it means
     * you need to read the next byte.
     * @param bytes
     * @return
     */
    public static int getStringLength(final InputStream is)
            throws IOException {
        int count = 0;
        int shift = 0;
        boolean more = true;
        while (more) {
            byte b = (byte) is.read();
            count |= (b & 0x7F) << shift;
            shift += 7;
            if ((b & 0x80) == 0) {
                more = false;
            }
        }
        return count;
    }
}

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