get File MD5 String - Android File Input Output

Android examples for File Input Output:File Hash

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Description

get File MD5 String

Demo Code


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

import java.security.MessageDigest;

public class Main {

    protected static char hexDigits[] = { '0', '1', '2', '3', '4', '5',
            '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
    protected static MessageDigest messagedigest = null;

    public static String getFileMD5String(File file) throws IOException {
        InputStream fis;/*from   w  w  w. j a v  a2s . c  o  m*/
        fis = new FileInputStream(file);
        byte[] buffer = new byte[1024];
        int numRead = 0;
        while ((numRead = fis.read(buffer)) > 0) {
            messagedigest.update(buffer, 0, numRead);
        }
        fis.close();
        return bufferToHex(messagedigest.digest());
    }

    private static String bufferToHex(byte bytes[]) {
        return bufferToHex(bytes, 0, bytes.length);
    }

    private static String bufferToHex(byte bytes[], int m, int n) {
        StringBuffer stringbuffer = new StringBuffer(2 * n);
        int k = m + n;
        for (int l = m; l < k; l++) {
            appendHexPair(bytes[l], stringbuffer);
        }
        return stringbuffer.toString();
    }

    private static void appendHexPair(byte bt, StringBuffer stringbuffer) {
        char c0 = hexDigits[(bt & 0xf0) >> 4];// ? 4 ?, >>> ?,? 
        char c1 = hexDigits[bt & 0xf];// ? 4 ? 
        stringbuffer.append(c0);
        stringbuffer.append(c1);
    }
}

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