Java MD5 String md5(File file)

Description

md

License

Apache License

Declaration

public static String md5(File file) 

Method Source Code

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

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.math.BigInteger;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.security.MessageDigest;

import java.util.Stack;

public class Main {
    private static final char[] LETTERS = "0123456789ABCDEF".toCharArray();

    public static String md5(File file) {
        if (!file.exists()) {
            return null;
        }/*  ww  w . ja v  a 2 s. c  o m*/
        if (!file.isDirectory()) {
            return getMd5ByFile(file);
        }
        StringBuffer buf = new StringBuffer();
        Stack<File> stack = new Stack<File>();
        stack.push(file);
        while (!stack.empty()) {
            File f = stack.pop();
            if (f.isFile()) {
                buf.append(getMd5ByFile(f));
            } else {
                for (File s : f.listFiles()) {
                    stack.push(s);
                }
            }
        }
        return md5(buf.toString());
    }

    public static String md5(String str) {
        MessageDigest md5 = null;
        try {
            md5 = MessageDigest.getInstance("MD5");
        } catch (Exception e) {
            e.printStackTrace();
            return "";
        }

        byte[] md5Bytes = new byte[0];
        try {
            md5Bytes = md5.digest(str.getBytes("UTF-8"));

            StringBuffer hexValue = new StringBuffer();

            for (int i = 0; i < md5Bytes.length; i++) {
                int val = ((int) md5Bytes[i]) & 0xff;
                if (val < 16)
                    hexValue.append("0");
                hexValue.append(Integer.toHexString(val));
            }

            return hexValue.toString();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }

        return null;
    }

    private static String getMd5ByFile(File file) {
        String value = null;
        FileInputStream in = null;
        try {
            in = new FileInputStream(file);
        } catch (FileNotFoundException e1) {
            e1.printStackTrace();
        }
        if (in == null) {
            return "<error>";
        }
        try {
            MappedByteBuffer byteBuffer = in.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, file.length());
            MessageDigest md5 = MessageDigest.getInstance("MD5");
            md5.update(byteBuffer.toString().getBytes("UTF-8"));
            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;
    }

    private static String toHexString(byte[] bytes) {
        char[] values = new char[bytes.length * 2];
        int i = 0;
        for (byte b : bytes) {
            values[i++] = LETTERS[((b & 0xF0) >>> 4)];
            values[i++] = LETTERS[b & 0xF];
        }
        return String.valueOf(values);
    }
}

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