计算文件MD5码类

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;

public class GetFileMD5 {
  protected static char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9','a', 'b', 'c', 'd', 'e', 'f' };
  protected static MessageDigest messagedigest = null;

  static{
    try{
      messagedigest = MessageDigest.getInstance("MD5");
    }catch(NoSuchAlgorithmException nsaex){
      System.err.println(GetFileMD5.class.getName()+"初始化失败，MessageDigest不支持MD5Util。");
      nsaex.printStackTrace();
    }
  }

  public static String getFileMD5String(File file) throws IOException {
    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());
  }

  public static String getMD5String(String s) {
    return getMD5String(s.getBytes());
  }

  public static String getMD5String(byte[] bytes) {
    messagedigest.update(bytes);
    return bufferToHex(messagedigest.digest());
  }

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

  public static boolean checkPassword(String password, String md5PwdStr) {
    String s = getMD5String(password);
    return s.equals(md5PwdStr);
  }
}


调用

import com.jmeter.com.GetFileMD5; //类存放位置

import java.io.File;
import java.io.IOException;

public class Test {
  public static void main(String[] args) throws IOException {
    long begin = System.currentTimeMillis();
    File big = new File("C:\\Users\\jgh\\Downloads\\123.jmx");
    String md5=GetFileMD5.getFileMD5String(big);
    long end = System.currentTimeMillis();
    System.out.println("md5:"+md5+" time:"+((end-begin)/1000)+"s");
    }
}


返回结果

Java计算文件MD5值_java