98 lines
2.7 KiB
Java
98 lines
2.7 KiB
Java
/**
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* Copyright © 2012-2014 <a href="https://github.com/thinkgem/jeesite">JeeSite</a> All rights reserved.
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*/
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package com.nis.util;
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import java.io.ByteArrayInputStream;
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import java.io.ByteArrayOutputStream;
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import java.io.FileInputStream;
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import java.io.IOException;
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import java.io.InputStream;
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import java.security.MessageDigest;
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import java.security.NoSuchAlgorithmException;
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import org.apache.commons.codec.digest.DigestUtils;
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/**
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* 字符串工具类, 继承org.apache.commons.lang3.StringUtils类
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* @author ThinkGem
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* @version 2013-05-22
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*/
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public class MD5Utils {
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/**
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* 字符串转为MD532位小写
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* @param plain
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* @return
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*/
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public static String md5LowerCase(String plain) throws Exception {
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String re_md5 = new String();
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MessageDigest md = MessageDigest.getInstance("MD5");
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md.update(plain.getBytes());
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byte b[] = md.digest();
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int i;
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StringBuffer buf = new StringBuffer("");
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for (int offset = 0; offset < b.length; offset++) {
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i = b[offset];
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if (i < 0)
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i += 256;
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if (i < 16)
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buf.append("0");
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buf.append(Integer.toHexString(i));
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}
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re_md5 = buf.toString();
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return re_md5;
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}
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public static byte[] createChecksum(String filename) throws IOException, NoSuchAlgorithmException {
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InputStream fis = new FileInputStream(filename);
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byte[] buffer = new byte[1024];
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MessageDigest complete = MessageDigest.getInstance("MD5");
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int numRead;
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do {
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numRead = fis.read(buffer);
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if (numRead > 0) {
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complete.update(buffer, 0, numRead);
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}
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} while (numRead != -1);
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fis.close();
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return complete.digest();
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}
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public static String getMD5Checksum(String filename) throws NoSuchAlgorithmException, IOException {
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byte[] b = createChecksum(filename);
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StringBuffer result = new StringBuffer();
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for (int i = 0; i < b.length; i++) {
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result.append(Integer.toString((b[i] & 0xff) + 0x100, 16).substring(1));
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}
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return result.toString();
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}
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public static void main(String[] args) throws NoSuchAlgorithmException, IOException {
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long start1 = System.currentTimeMillis();
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String md5Checksum = getMd5ByIS(new FileInputStream("f:\\1.iso"));
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System.out.println(md5Checksum);
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long start2 = System.currentTimeMillis();
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System.out.println("第一次用时" + (start2 - start1));
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String md5Checksum1 = getMD5Checksum("f:\\1.iso");
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long start3 = System.currentTimeMillis();
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System.out.println(md5Checksum1);
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System.out.println("第二次用时" + (start3 - start2));
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}
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/**
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* 这种方式计算大文件时更快一些
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* @param fis
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* @return
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* @throws IOException
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* @throws NoSuchAlgorithmException
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*/
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public static String getMd5ByIS(InputStream is) throws IOException, NoSuchAlgorithmException {
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return DigestUtils.md5Hex(is);
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}
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}
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