MD5加密工具类

MD5加密工具类

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.DigestInputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5Tools {
    private final static String encoding = "utf-8";
    /**
     * 16进制的字符数组
     */
    private final static String[] hexDigits = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d",
            "e", "f"};

    public static void main(String[] args) {
        String pass = "jyl74657";//062885f2e1b61fa36f38365336d427d7
        String s1 = MD5Tools.MD5Encode(pass, true);
        System.out.println(s1);
        String s2 = MD5Tools.MD5Encode(s1, false);
        System.out.println(s2);
    }

    /**
     * @param source    需要加密的原字符串
     * @param uppercase 是否转为大写字符串
     * @return
     */
    public static String MD5Encode(String source, boolean uppercase) {
        String result = null;
        try {
            result = source;
            // 获得MD5摘要对象
            MessageDigest messageDigest = MessageDigest.getInstance("MD5");
            // 使用指定的字节数组更新摘要信息
            messageDigest.update(result.getBytes(encoding));
            // messageDigest.digest()获得16位长度
            result = byteArrayToHexString(messageDigest.digest());

        } catch (Exception e) {
            e.printStackTrace();
        }
        return uppercase ? result.toUpperCase() : result;
    }

    /**
     * 转换字节数组为16进制字符串
     *
     * @param bytes 字节数组
     * @return
     */
    private static String byteArrayToHexString(byte[] bytes) {
        StringBuilder stringBuilder = new StringBuilder();
        for (byte tem : bytes) {
            stringBuilder.append(byteToHexString(tem));
        }
        return stringBuilder.toString();
    }

    /**
     * 转换byte到16进制
     *
     * @param b 要转换的byte
     * @return 16进制对应的字符
     */
    private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0) {
            n = 256 + n;
        }
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }

    /**
     * 文件MD5
     *
     * @return
     * @throws IOException
     */
    public static String fileMD5(InputStream fileInputStream) throws IOException {
        // 缓冲区大小（这个可以抽出一个参数）
        int bufferSize = 256 * 1024;
        DigestInputStream digestInputStream = null;
        try {
            // 拿到一个MD5转换器（同样，这里可以换成SHA1）
            MessageDigest messageDigest = MessageDigest.getInstance("MD5");
            // 使用DigestInputStream
            digestInputStream = new DigestInputStream(fileInputStream, messageDigest);
            // read的过程中进行MD5处理，直到读完文件
            byte[] buffer = new byte[bufferSize];
            while (digestInputStream.read(buffer) > 0) ;
            // 获取最终的MessageDigest
            messageDigest = digestInputStream.getMessageDigest();
            // 拿到结果，也是字节数组，包含16个元素
            byte[] resultByteArray = messageDigest.digest();
            // 同样，把字节数组转换成字符串
            return byteArrayToHexString(resultByteArray);
        } catch (NoSuchAlgorithmException e) {
            return null;
        } finally {
            try {
                digestInputStream.close();
            } catch (Exception e) {
            }
            try {
                fileInputStream.close();
            } catch (Exception e) {
            }
        }
    }

    /**
     * 文件MD5
     *
     * @param file
     * @return
     * @throws IOException
     */
    public static String fileMD5(File file) throws IOException {
        // 缓冲区大小（这个可以抽出一个参数）
        int bufferSize = 256 * 1024;
        DigestInputStream digestInputStream = null;
        FileInputStream fileInputStream = null;
        try {
            // 拿到一个MD5转换器（同样，这里可以换成SHA1）
            MessageDigest messageDigest = MessageDigest.getInstance("MD5");
            fileInputStream = new FileInputStream(file);
            // 使用DigestInputStream
            digestInputStream = new DigestInputStream(fileInputStream, messageDigest);
            // read的过程中进行MD5处理，直到读完文件
            byte[] buffer = new byte[bufferSize];
            while (digestInputStream.read(buffer) > 0) ;
            // 获取最终的MessageDigest
            messageDigest = digestInputStream.getMessageDigest();
            // 拿到结果，也是字节数组，包含16个元素
            byte[] resultByteArray = messageDigest.digest();
            // 同样，把字节数组转换成字符串
            return byteArrayToHexString(resultByteArray);
        } catch (NoSuchAlgorithmException e) {
            return null;
        } finally {
            try {
                digestInputStream.close();
            } catch (Exception e) {
            }
            try {
                fileInputStream.close();
            } catch (Exception e) {
            }
        }
    }
}