java获取文件md5码

package pri.yang.MD5;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import org.apache.commons.codec.binary.Hex;

public class BigFileMD5 {
static MessageDigest MD5 = null;

static{
try{
MD5 = MessageDigest.getInstance("MD5");
}catch(NoSuchAlgorithmException e){
e.printStackTrace();
}
}

public static void main(String[] args){
if(args.length < 1){
System.out.println("need one argument as file path!");
}else{
String filePath = args[0];
//File file = new File("F:\\BaiduYunDownload\\jdk-7u79-linux-x64.tar.gz");
File file = new File(filePath);
if(!file.exists()){
System.out.println("incorrect file path!");
}else{
String md5 = getMD5(file);
System.out.println("===============MD5===============");
System.out.println(md5);
System.out.println("===============MD5===============");

}

}
}

/**
* 对一个文件获取md5值
* @return md5串
*/
public static String getMD5(File file) {
FileInputStream fileInputStream = null;
try {
fileInputStream = new FileInputStream(file);
byte[] buffer = new byte[8192];
int length;
while ((length = fileInputStream.read(buffer)) != -1) {
MD5.update(buffer, 0, length);
}

return new String(Hex.encodeHex(MD5.digest()));
} catch (FileNotFoundException e) {
e.printStackTrace();
return null;
} catch (IOException e) {
e.printStackTrace();
return null;
} finally {
try {
if (fileInputStream != null)
fileInputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}