(java)MD5生成文件的MD5值

package com.md5.test1;
 
import java.io.File;
 
public class Test {
	
	public static void main(String[] args) {
		
		String value = "";
		File file = new File("E:\\a.txt");
        value = Md5Util.getMd5ByFile(file);
        System.out.println(value);
         
        File file2 = new File("E:\\b.txt");
        value = Md5Util.getMd5ByFile(file2);
        System.out.println(value);
         
        File file3 = new File("E:\\c.txt");
        value = Md5Util.getMd5ByFile(file3);
        System.out.println(value);
         
	}
	
}
 
package com.md5.test1;
 
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.math.BigInteger;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.security.MessageDigest;
 
public class Md5Util {
    // 標準的構造函數，調用md5Init函數進行初始化工作
    public Md5Util() {
        md5Init();
        return;
    }
 
    // RFC1321中定義的標準4*4矩陣的常量定義。
    static final int S11 = 7, S12 = 12, S13 = 17, S14 = 22;
    static final int S21 = 5, S22 = 9, S23 = 14, S24 = 20;
    static final int S31 = 4, S32 = 11, S33 = 16, S34 = 23;
    static final int S41 = 6, S42 = 10, S43 = 15, S44 = 21;
 
    // 按RFC1321標準定義不可變byte型數組PADDING
    static final byte[] PADDING = { -128, 0, 0, 0, 0, 0, 0, 0,
 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
 
    // MD5計算過程中的3組核心數據，採用數組形式存放
    private long[] state = new long[4]; // 計算狀態(分別對應a b c d)
 
    private byte[] buffer = new byte[64]; // 分配64個字節私有緩衝區
 
    private long[] count = new long[2]; // 位個數
 
    // 最新一次計算結果的16進制ASCII字符串表示，代表了16個字符串形式的MD5值
    public String resultStr;
 
    // 最新一次計算結果的2進制數組表示，一共16個字節，代表了128bit形式的MD5值
    public byte[] digest = new byte[16];
 
    /**
     * 獲得兩次MD5加密的字符串
     * 
     * @param str
     * @return
     */
    public String getTwiceMD5ofString(String str) {
        return getMD5ofStr(getMD5ofStr(str));
    }
 
    /**
     * MD5_Encoding類提供的主要的接口函數getMD5ofStr，用來進行數據加密變換。
     * 
     * 調用其可對任意字符串進行加密運算，並以字符串形式返回加密結果。
     * 
     * @param in
     * @return
     */
    public String getMD5ofStr(String in) {
        md5Init(); // 初始化
        md5Update(in.getBytes(), in.length());// 調用MD5的主計算過程
        md5Final(); // 輸出結果到digest數組中
        for (int i = 0; i < 16; i++) {
            resultStr += byteToHEX(digest[i]); // 將digest數組中的每個byte型數據轉爲16進制形式的字符串
        }
        return resultStr;
    }
 
    // md5初始化函數.初始化核心變量.
    private void md5Init() {
        state[0] = 0x67452301L; // 定義state爲RFC1321中定義的標準幻數
        state[1] = 0xefcdab89L; // 定義state爲RFC1321中定義的標準幻數
        state[2] = 0x98badcfeL; // 定義state爲RFC1321中定義的標準幻數
        state[3] = 0x10325476L; // 定義state爲RFC1321中定義的標準幻數
        count[0] = count[1] = 0L; // 初始化爲0
        resultStr = "" ;// 初始化resultStr字符串爲空
        for (int i = 0; i < 16; i++) {
            digest[i] = 0;// 初始化digest數組元素爲0
        }
        return;
    }
 
    // 定義F G H I 爲4個基數 ，即爲4個基本的MD5函數,進行簡單的位運算
    private long F(long x, long y, long z) {
        return (x & y) | ((~x) & z);
    }
 
    private long G(long x, long y, long z) {
        return (x & z) | (y & (~z));
    }
 
    private long H(long x, long y, long z) {
        return x ^ y ^ z;
    }
 
    private long I(long x, long y, long z) {
        return y ^ (x | (~z));
    }
 
    // FF,GG,HH和II調用F,G,H,I函數進行進一步變換
    private long FF(long a, long b, long c, long d, long x, long s, long ac) {
        a += F(b, c, d) + x + ac;
        a = ((int) a << s) | ((int) a >>> (32 - s)); // 這裏long型數據右移時使用無符號右移運算符>>>
        a += b;
        return a;
    }
 
    private long GG(long a, long b, long c, long d, long x, long s, long ac) {
        a += G(b, c, d) + x + ac;
        a = ((int) a << s) | ((int) a >>> (32 - s)); // 這裏long型數據右移時使用無符號右移運算符>>>
        a += b;
        return a;
    }
 
    private long HH(long a, long b, long c, long d, long x, long s, long ac) {
        a += H(b, c, d) + x + ac;
        a = ((int) a << s) | ((int) a >>> (32 - s));// 這裏long型數據右移時使用無符號右移運算符>>>
        a += b;
        return a;
    }
 
    private long II(long a, long b, long c, long d, long x, long s, long ac) {
        a += I(b, c, d) + x + ac;
        a = ((int) a << s) | ((int) a >>> (32 - s));// 這裏long型數據右移時使用無符號右移運算符>>>
        a += b;
        return a;
    }
 
    // MD5的主計算過程，input是需要變換的二進制字節串，inputlen是長度
    private void md5Update(byte[] input, int inputLen) {
        int i = 0, index, partLen;
        byte[] block = new byte[64]; // 分配64個字節緩衝區
        // 根據count計算index值。這裏long型數據右移時使用無符號右移運算符>>>
        index = (int) (count[0] >>> 3) & 0x3F;
        if ((count[0] += (inputLen << 3)) < (inputLen << 3)) {
            count[1]++;
        }
        count[1] += (inputLen >>> 29); // 這裏int型數據右移時使用無符號右移運算符>>>
        partLen = 64 - index; // 計算partLen值
        if (inputLen >= partLen) {
            md5Memcpy(buffer, input, index, 0, partLen);
            md5Transform(buffer);
            for (i = partLen; i + 63 < inputLen; i += 64) {
                md5Memcpy(block, input, 0, i, 64);
                md5Transform(block);
            }
            index = 0;
        } else {
            i = 0;
        }
        md5Memcpy(buffer, input, index, i, inputLen - i);
    }
 
    // 整理和填寫輸出結果，結果放到數組digest中。
    private void md5Final() {
        byte[] bits = new byte[8];
        int index, padLen;
        Encode(bits, count, 8);
        index = (int) (count[0] >>> 3) & 0x3f; // 這裏long型數據右移時使用無符號右移運算符>>>
        padLen = (index < 56) ? (56 - index) : (120 - index);
        md5Update(PADDING, padLen);
        md5Update(bits, 8);
        Encode(digest, state, 16);
    }
 
    // byte數組的塊拷貝函數，將input數組中的起始位置爲inpos，長度len的數據拷貝到output數組起始位置outpos處。
    private void md5Memcpy(byte[] output, byte[] input, int outpos, int inpos, int len) {
        int i;
        for (i = 0; i < len; i++) {
            output[outpos + i] = input[inpos + i];
        }
    }
 
    // MD5核心變換計算程序，由md5Update函數調用，block是分塊的原始字節數組
    private void md5Transform(byte block[]) {
        long a = state[0], b = state[1], c = state[2], d = state[3];
        long[] x = new long[16];
        Decode(x, block, 64);
        // 進行4級級聯運算
        // 第1級
        a = FF(a, b, c, d, x[0], S11, 0xd76aa478L); /* 1 */
        d = FF(d, a, b, c, x[1], S12, 0xe8c7b756L); /* 2 */
        c = FF(c, d, a, b, x[2], S13, 0x242070dbL); /* 3 */
        b = FF(b, c, d, a, x[3], S14, 0xc1bdceeeL); /* 4 */
        a = FF(a, b, c, d, x[4], S11, 0xf57c0fafL); /* 5 */
        d = FF(d, a, b, c, x[5], S12, 0x4787c62aL); /* 6 */
        c = FF(c, d, a, b, x[6], S13, 0xa8304613L); /* 7 */
        b = FF(b, c, d, a, x[7], S14, 0xfd469501L); /* 8 */
        a = FF(a, b, c, d, x[8], S11, 0x698098d8L); /* 9 */
        d = FF(d, a, b, c, x[9], S12, 0x8b44f7afL); /* 10 */
        c = FF(c, d, a, b, x[10], S13, 0xffff5bb1L); /* 11 */
        b = FF(b, c, d, a, x[11], S14, 0x895cd7beL); /* 12 */
        a = FF(a, b, c, d, x[12], S11, 0x6b901122L); /* 13 */
        d = FF(d, a, b, c, x[13], S12, 0xfd987193L); /* 14 */
        c = FF(c, d, a, b, x[14], S13, 0xa679438eL); /* 15 */
        b = FF(b, c, d, a, x[15], S14, 0x49b40821L); /* 16 */
 
        // 第2級
        a = GG(a, b, c, d, x[1], S21, 0xf61e2562L); /* 17 */
        d = GG(d, a, b, c, x[6], S22, 0xc040b340L); /* 18 */
        c = GG(c, d, a, b, x[11], S23, 0x265e5a51L); /* 19 */
        b = GG(b, c, d, a, x[0], S24, 0xe9b6c7aaL); /* 20 */
        a = GG(a, b, c, d, x[5], S21, 0xd62f105dL); /* 21 */
        d = GG(d, a, b, c, x[10], S22, 0x2441453L); /* 22 */
        c = GG(c, d, a, b, x[15], S23, 0xd8a1e681L); /* 23 */
        b = GG(b, c, d, a, x[4], S24, 0xe7d3fbc8L); /* 24 */
        a = GG(a, b, c, d, x[9], S21, 0x21e1cde6L); /* 25 */
        d = GG(d, a, b, c, x[14], S22, 0xc33707d6L); /* 26 */
        c = GG(c, d, a, b, x[3], S23, 0xf4d50d87L); /* 27 */
        b = GG(b, c, d, a, x[8], S24, 0x455a14edL); /* 28 */
        a = GG(a, b, c, d, x[13], S21, 0xa9e3e905L); /* 29 */
        d = GG(d, a, b, c, x[2], S22, 0xfcefa3f8L); /* 30 */
        c = GG(c, d, a, b, x[7], S23, 0x676f02d9L); /* 31 */
        b = GG(b, c, d, a, x[12], S24, 0x8d2a4c8aL); /* 32 */
 
        // 第3級
        a = HH(a, b, c, d, x[5], S31, 0xfffa3942L); /* 33 */
        d = HH(d, a, b, c, x[8], S32, 0x8771f681L); /* 34 */
        c = HH(c, d, a, b, x[11], S33, 0x6d9d6122L); /* 35 */
        b = HH(b, c, d, a, x[14], S34, 0xfde5380cL); /* 36 */
        a = HH(a, b, c, d, x[1], S31, 0xa4beea44L); /* 37 */
        d = HH(d, a, b, c, x[4], S32, 0x4bdecfa9L); /* 38 */
        c = HH(c, d, a, b, x[7], S33, 0xf6bb4b60L); /* 39 */
        b = HH(b, c, d, a, x[10], S34, 0xbebfbc70L); /* 40 */
        a = HH(a, b, c, d, x[13], S31, 0x289b7ec6L); /* 41 */
        d = HH(d, a, b, c, x[0], S32, 0xeaa127faL); /* 42 */
        c = HH(c, d, a, b, x[3], S33, 0xd4ef3085L); /* 43 */
        b = HH(b, c, d, a, x[6], S34, 0x4881d05L); /* 44 */
        a = HH(a, b, c, d, x[9], S31, 0xd9d4d039L); /* 45 */
        d = HH(d, a, b, c, x[12], S32, 0xe6db99e5L); /* 46 */
        c = HH(c, d, a, b, x[15], S33, 0x1fa27cf8L); /* 47 */
        b = HH(b, c, d, a, x[2], S34, 0xc4ac5665L); /* 48 */
 
        // 第4級
        a = II(a, b, c, d, x[0], S41, 0xf4292244L); /* 49 */
        d = II(d, a, b, c, x[7], S42, 0x432aff97L); /* 50 */
        c = II(c, d, a, b, x[14], S43, 0xab9423a7L); /* 51 */
        b = II(b, c, d, a, x[5], S44, 0xfc93a039L); /* 52 */
        a = II(a, b, c, d, x[12], S41, 0x655b59c3L); /* 53 */
        d = II(d, a, b, c, x[3], S42, 0x8f0ccc92L); /* 54 */
        c = II(c, d, a, b, x[10], S43, 0xffeff47dL); /* 55 */
        b = II(b, c, d, a, x[1], S44, 0x85845dd1L); /* 56 */
        a = II(a, b, c, d, x[8], S41, 0x6fa87e4fL); /* 57 */
        d = II(d, a, b, c, x[15], S42, 0xfe2ce6e0L); /* 58 */
        c = II(c, d, a, b, x[6], S43, 0xa3014314L); /* 59 */
        b = II(b, c, d, a, x[13], S44, 0x4e0811a1L); /* 60 */
        a = II(a, b, c, d, x[4], S41, 0xf7537e82L); /* 61 */
        d = II(d, a, b, c, x[11], S42, 0xbd3af235L); /* 62 */
        c = II(c, d, a, b, x[2], S43, 0x2ad7d2bbL); /* 63 */
        b = II(b, c, d, a, x[9], S44, 0xeb86d391L); /* 64 */
 
        // 分別累加到state[0],state[1],state[2],state[3]
        state[0] += a;
        state[1] += b;
        state[2] += c;
        state[3] += d;
    }
 
    // 把byte型數據轉換爲無符號long型數據
    private static long byteToul(byte b) {
        return b > 0 ? b : (b & 0x7F + 128);
    }
 
    // 把byte類型的數據轉換成十六進制ASCII字符表示
    private static String byteToHEX(byte in) {
        char[] DigitStr = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
        char[] out = new char[2];
        out[0] = DigitStr[(in >> 4) & 0x0F]; // 取高4位
        out[1] = DigitStr[in & 0x0F]; // 取低4位
        String s = new String(out);
        return s;
    }
 
    // 將long型數組按順序拆成byte型數組,長度爲len
    private void Encode(byte[] output, long[] input, int len) {
        int i, j;
        for (i = 0, j = 0; j < len; i++, j += 4) {
            output[j] = (byte) (input[i] & 0xffL);
            output[j + 1] = (byte) ((input[i] >>> 8) & 0xffL);
            output[j + 2] = (byte) ((input[i] >>> 16) & 0xffL);
            output[j + 3] = (byte) ((input[i] >>> 24) & 0xffL);
        }
    }
 
    // 將byte型數組按順序合成long型數組，長度爲len
    private void Decode(long[] output, byte[] input, int len) {
        int i, j;
        for (i = 0, j = 0; j < len; i++, j += 4) {
            output[i] = byteToul(input[j]) | (byteToul(input[j + 1]) << 8) | (byteToul(input[j + 2]) << 16) | (byteToul(input[j + 3]) << 24);
        }
        return;
    }
 
    public static String getMd5ByFile(File file) {
        String value = null;
        FileInputStream in = null;
        try {
            in = new FileInputStream(file);
        } catch (FileNotFoundException e1) {
            e1.printStackTrace();
        }
        try {
            MappedByteBuffer byteBuffer = in.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, file.length());
            MessageDigest md5 = MessageDigest.getInstance("MD5");
            md5.update(byteBuffer);
            BigInteger bi = new BigInteger(1, md5.digest());
            value = bi.toString(16);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (null != in) {
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return value;
    }
    
    
}
 
參考：https://www.2cto.com/kf/201507/413557.html