com.eryansky.common.utils.encode.MD5Util.java Source code

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Here is the source code for com.eryansky.common.utils.encode.MD5Util.java

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/**
 *  Copyright (c) 2012-2014 http://www.eryansky.com
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 */
package com.eryansky.common.utils.encode;

import org.apache.commons.lang3.StringUtils;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * MD5.
 * @author &Eryan eryanwcp@gmail.com
 * @date   2012-1-9?3:15:25
 */
public class MD5Util {
    /**  
    * ????? 16 ,apache?  
    */
    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;
    static {
        try {
            messagedigest = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
    }

    /**
     * ?MD5
     * @param file
     * @return
     * @throws IOException
     * @date   2012-1-9?3:15:43
     */
    public static String getFileMD5String(File file) throws IOException {
        InputStream fis;
        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());
    }

    /**
     * ?MD5 32??
     * @param str
     * @return
     * @date   2012-1-9?3:16:04
     */
    public static String getStringMD5(String str) {
        if (StringUtils.isEmpty(str)) {
            return "";
        }
        byte[] buffer = str.getBytes();
        messagedigest.update(buffer);
        return bufferToHex(messagedigest.digest());
    }

    public 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);
    }

    //
    public static void main(String[] args) {
        System.out.println(MD5Util.getStringMD5("123456"));//21232f297a57a5a743894a0e4a801fc3
    }
}