package com.yihu.ehr.util.encrypt;


import com.yihu.ehr.util.encode.HexEncode;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.lang.reflect.Method;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.security.AccessController;
import java.security.MessageDigest;
import java.security.PrivilegedAction;

/**
 * @created  Air 2015/6/2.
 */
public class MD5 {
    static public String hash(String str) throws Exception {
        MessageDigest messageDigest = null;
        messageDigest = MessageDigest.getInstance("MD5");
        messageDigest.reset();
        messageDigest.update(str.getBytes());

        return HexEncode.toHexString(messageDigest.digest());
    }

    public static String getMd5ByFile(File file) throws FileNotFoundException {
        String value = null;
        FileInputStream in = new FileInputStream(file);
        MappedByteBuffer byteBuffer =null;
        try {
            byteBuffer = in.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, file.length());
            MessageDigest md5 = MessageDigest.getInstance("MD5");
            md5.update(byteBuffer);
//            BigInteger bi = new BigInteger(1, md5.digest());
//            value = bi.toString(16);
            value= HexEncode.toHexString(md5.digest());
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if(null != in) {
                try {
                    in.close();
                    clean(byteBuffer);
                } catch (IOException e) {
                    e.printStackTrace();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
        return value;
    }

    public static void clean(final Object buffer) throws Exception {
        AccessController.doPrivileged(new PrivilegedAction() {
            public Object run() {
                try {
                    Method getCleanerMethod = buffer.getClass().getMethod("cleaner", new Class[0]);
                    getCleanerMethod.setAccessible(true);
                    sun.misc.Cleaner cleaner = (sun.misc.Cleaner) getCleanerMethod.invoke(buffer, new Object[0]);
                    cleaner.clean();
                } catch (Exception e) {
                    e.printStackTrace();
                }
                return null;
            }
        });

    }

}