java实现MD5数据加密

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原文链接：https://my.oschina.net/AaronDMC/blog/750788

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#java #python

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package net.sc.common.md5;

import java.io.File;
import java.io.FileInputStream;
import java.math.BigInteger;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

/**
 * @Author Aaron
 * @CreateTime 2014-6-16下午05:28:11
 * @Version 1.0
 * @Desc 用MD5对数据进行加密
 */
public class MD5 {

	static final Logger log = LogManager.getLogger(MD5.class);

	MessageDigest md5;

	static final char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

	public MD5() {
		try {
			// 获得MD5摘要算法的 MessageDigest 对象
			md5 = MessageDigest.getInstance("MD5");
		} catch (NoSuchAlgorithmException e) {
			log.error("创建MD5对象出错, ", e);
			throw new IllegalArgumentException("创建md5对象时出错");
		}
	}

	public synchronized String getMD5(String s) {
		return this.getMD5(s.getBytes());
	}

	public synchronized String getMD5(byte[] btInput) {
		try {
			// 使用指定的字节更新摘要
			md5.update(btInput);
			// 获得密文
			byte[] md = md5.digest();
			// 把密文转换成十六进制的字符串形式
			int j = md.length;
			char str[] = new char[j * 2];
			int k = 0;
			for (int i = 0; i < j; i++) {
				byte byte0 = md[i];
				str[k++] = hexDigits[byte0 >>> 4 & 0xf];
				str[k++] = hexDigits[byte0 & 0xf];
			}
			return new String(str);
		} catch (Exception e) {
			log.error("生成MD5码时出错,", e);
			throw new IllegalArgumentException("生成MD5出错");
		}
	}

	public String getFileMD5(String filePath) {
		File md5File = new File(filePath);
		return this.getFileMD5(md5File);
	}

	public String getFileMD5(File md5File) {
		String value = "";
		if (!md5File.exists()) {
			log.error("计算MD5码时,对应路径文件:{} 不存在.", md5File);
			return value;
		}
		try (FileInputStream in = new FileInputStream(md5File)) {
			MappedByteBuffer byteBuffer = in.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, md5File.length());
			MessageDigest md5 = MessageDigest.getInstance("MD5");
			md5.update(byteBuffer);
			BigInteger bi = new BigInteger(1, md5.digest());
			value = bi.toString(16);
		} catch (Exception e) {
			log.error(String.format("计算文件:%s 的MD5码出错!", md5File.getPath()), e);
		} finally {

		}
		return value;
	}

}

转载于:https://my.oschina.net/AaronDMC/blog/750788