MD5工具类

package com.xu.utlis;


import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
 

/**
 * @FileName MD5Helper.java
 * @Description: 
 *  MD5加密解密
 * @author 
 * @version 1.0
 * 
 */
public class MD5Helper {
	private final static String KEY_MD5 = "MD5";
	private final static String KEY_SHA = "SHA-512";

	private static char hexChars[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };

	public static void main(String[] args) {
		String password="123456";
		String encryPasswordStr = encrypt32MD5(password);
		System.out.println(encryPasswordStr);
	}
	/**
	 * 返回32位MD5加密密码
	 * 
	 * @param value
	 *            加密串
	 * @return
	 */
	public static String encrypt32MD5(String value) {
		try {
			byte[] bytes = value.getBytes();
			MessageDigest md = MessageDigest.getInstance(KEY_MD5);

			md.update(bytes);
			bytes = md.digest();
			int j = bytes.length;
			char[] chars = new char[j * 2];
			int k = 0;
			for (int i = 0; i < bytes.length; i++) {
				byte b = bytes[i];
				chars[k++] = hexChars[b >>> 4 & 0xf];
				chars[k++] = hexChars[b & 0xf];
			}
			return new String(chars);
		} catch (NoSuchAlgorithmException e) {
			return null;
		}
	}

	/**
	 * 返回16位MD5加密密码
	 * 
	 * @param value
	 *            加密串
	 * @return
	 */
	public static String encrypt16MD5(String value) {
		try {
			byte[] bytes = value.getBytes();
			MessageDigest md = MessageDigest.getInstance(KEY_MD5);
			md.update(bytes);
			bytes = md.digest();
			int j = bytes.length;
			char[] chars = new char[j * 2];
			int k = 0;
			for (int i = 0; i < bytes.length; i++) {
				byte b = bytes[i];
				chars[k++] = hexChars[b >>> 4 & 0xf];
				chars[k++] = hexChars[b & 0xf];
			}
			return new String(chars).substring(8, 24);
		} catch (NoSuchAlgorithmException e) {
			return null;
		}
	}

	/**
	 * 返回32位SHA加密密码(注：SHA比md5安全)
	 * 
	 * @param value
	 *            加密串
	 * @return
	 */
	public static String encrypt32SHA(String value) {
		try {
			byte[] bytes = value.getBytes();
			MessageDigest md = MessageDigest.getInstance(KEY_SHA);

			md.update(bytes);
			bytes = md.digest();
			int j = bytes.length;
			char[] chars = new char[j * 2];
			int k = 0;
			for (int i = 0; i < bytes.length; i++) {
				byte b = bytes[i];
				chars[k++] = hexChars[b >>> 4 & 0xf];
				chars[k++] = hexChars[b & 0xf];
			}
			return new String(chars);
		} catch (NoSuchAlgorithmException e) {
			return null;
		}
	}

	/**
	 * 返回16位SHA加密密码(SHA比md5安全)
	 * 
	 * @param value
	 *            加密串
	 * @return
	 */
	public static String encrypt16SHA(String value) {
		try {
			byte[] bytes = value.getBytes();
			MessageDigest md = MessageDigest.getInstance(KEY_SHA);
			md.update(bytes);
			bytes = md.digest();
			int j = bytes.length;
			char[] chars = new char[j * 2];
			int k = 0;
			for (int i = 0; i < bytes.length; i++) {
				byte b = bytes[i];
				chars[k++] = hexChars[b >>> 4 & 0xf];
				chars[k++] = hexChars[b & 0xf];
			}
			return new String(chars).substring(8, 24);
		} catch (NoSuchAlgorithmException e) {
			return null;
		}
	}

	/**
	 * 获取文件的MD5值
	 * 
	 * @param file	文件
	 * @return
	 * @throws IOException
	 */
	public static String fileMD5(File file) throws IOException {
		MessageDigest messagedigest;
		try {
			messagedigest = MessageDigest.getInstance(KEY_MD5);
			FileInputStream in = new FileInputStream(file);
			FileChannel ch = in.getChannel();
			MappedByteBuffer byteBuffer = ch.map(FileChannel.MapMode.READ_ONLY, 0, file.length());
			messagedigest.update(byteBuffer);
			return bufferToHex(messagedigest.digest());
		} catch (NoSuchAlgorithmException e) {
			return null;
		}
	}

	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 = hexChars[(bt & 0xf0) >> 4];
		char c1 = hexChars[bt & 0xf];
		stringbuffer.append(c0);
		stringbuffer.append(c1);
	}
}