java计算过G文件md5 值计算

 package io.bigdata;

 import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.security.Provider;
 import java.security.Security;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.Set;

 import org.apache.commons.codec.digest.DigestUtils;

 public class Md5CaculateUtil {

     private Md5CaculateUtil(){

     }

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

     public static String getHash(String fileName,String hashType) throws IOException, NoSuchAlgorithmException{

         File f = new File(fileName);
         System.out.println(" -------------------------------------------------------------------------------");
         System.out.println("|当前文件名称:"+f.getName());
         System.out.println("|当前文件大小:"+(f.length()/1024/1024)+"MB");
         System.out.println("|当前文件路径[绝对]:"+f.getAbsolutePath());
         System.out.println("|当前文件路径[---]:"+f.getCanonicalPath());
         System.out.println(" -------------------------------------------------------------------------------");

         InputStream ins = new FileInputStream(f);

         byte[] buffer = new byte[8192];
         MessageDigest md5 = MessageDigest.getInstance(hashType);

         int len;
         while((len = ins.read(buffer)) != -1){
             md5.update(buffer, 0, len);
         }

         ins.close();
 //        也可以用apache自带的计算MD5方法
         return DigestUtils.md5Hex(md5.digest());
 //        自己写的转计算MD5方法
 //        return toHexString(md5.digest());
     }

     public static String getHash2(String fileName){
         File f = new File(fileName);
         return String.valueOf(f.lastModified());
     }

     protected static String toHexString(byte[] b){
         StringBuilder sb = new StringBuilder(b.length*2);
         for(int i=0;i<b.length;i++){
             sb.append(hexChar[(b[i] & 0xf0) >>> 4]);
             sb.append(hexChar[b[i] & 0x0f]);
         }
         return sb.toString();
     }

     /*
      * 获取MessageDigest支持几种加密算法
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
     private static String[] getCryptolmpls(String serviceType){

         Set result = new HashSet();
 //        all providers
         Provider[] providers = Security.getProviders();
         for(int i=0;i<providers.length;i++){
 //            get services provided by each provider
             Set keys = providers[i].keySet();
             for(Iterator it = keys.iterator();it.hasNext();){
                 String key = it.next().toString();
                 key = key.split(" ")[0];

                 if(key.startsWith(serviceType+".")){
                     result.add(key.substring(serviceType.length()+1));
                 }else if(key.startsWith("Alg.Alias."+serviceType+".")){
                     result.add(key.substring(serviceType.length()+11));
                 }
             }
         }
         return (String[]) result.toArray(new String[result.size()]);
     }

     public static void main(String[] args) throws Exception, Exception {
 //        调用方法
 //        String[] names = getCryptolmpls("MessageDigest");
 //        for(String name:names){
 //            System.out.println(name);
 //        }
         long start = System.currentTimeMillis();
         System.out.println("开始计算文件MD5值,请稍后...");
         String fileName = "E:\\Office_2010_Toolkit_2.2.3_XiaZaiBa.zip";
 ////        String fileName = "E:\\SoTowerStudio-3.1.0.exe";
         String hashType = "MD5";
         String hash = getHash(fileName,hashType);
         System.out.println("MD5:"+hash);
         long end = System.currentTimeMillis();
         System.out.println("一共耗时:"+(end-start)+"毫秒");
     }
 }

开始计算文件MD5值,请稍后...
-------------------------------------------------------------------------------
|当前文件名称:Office_2010_Toolkit_2.2.3_XiaZaiBa.zip
|当前文件大小:2437MB
|当前文件路径[绝对]:E:\Office_2010_Toolkit_2.2.3_XiaZaiBa.zip
|当前文件路径[---]:E:\Office_2010_Toolkit_2.2.3_XiaZaiBa.zip
-------------------------------------------------------------------------------
MD5:b1d269391c87942e5bb32b575baa0d79
一共耗时:18794毫秒

参考文章：http://sziitjiang.iteye.com/blog/1702961