java计算文件的MD5值

网上找的JAVA计算文件的MD5值的工具类，保存下做个记录。

package phreadpool;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.HashMap;
import java.util.Map;

public class FileMDFive {

public static void main(String[] args) {

System.out.println(FileMDFive.getFileMD5(new File("D:\\api.docx")));
}


/**
 * 根据文件计算出文件的MD5
 * @param file
 * @return
 */
public static String getFileMD5(File file) {
if (!file.isFile()) {
return null;
}

MessageDigest digest = null;
FileInputStream in = null;
byte buffer[] = new byte[1024];
int len;
try {
digest = MessageDigest.getInstance("MD5");
in = new FileInputStream(file);
while ((len = in.read(buffer, 0, 1024)) != -1) {
digest.update(buffer, 0, len);
}
in.close();

} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
BigInteger bigInt = new BigInteger(1, digest.digest());

return bigInt.toString(16);
}

/**
 * 获取文件夹中的文件的MD5值
 * @param file
 * @param listChild
 * @return
 */
public static  Map<String,String> getDirMD5(File file, boolean listChild){
if(! file.isDirectory()){
return null;
}

Map<String, String> map = new HashMap<String, String>();
String md5;

File[] files = file.listFiles();
for (int i = 0; i < files.length; i++) {
File file2 = files[i];
if(file2.isDirectory() && listChild){
map.putAll(getDirMD5(file2, listChild));
}else{
md5 = getFileMD5(file2);
if(md5 != null){
map.put(file2.getPath(), md5);
}
}
}
return map;
}

}