Java--我即几的MD5加密和校验

百度的时候发现有人无耻的用了写好的工具类，那我就更无耻了。。。我也用。

我是在：org.apache.commons.codec.digest.DigestUtils 这个类里面找到的一个工具

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.codec.digest;

import java.io.IOException;
import java.io.InputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

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

/**
 * Operations to simplify common {@link java.security.MessageDigest} tasks.
 * This class is immutable and thread-safe.
 *
 * @version $Id: DigestUtils.java 1634433 2014-10-27 01:10:47Z ggregory $
 */
public class DigestUtils {

    private static final int STREAM_BUFFER_LENGTH = 1024;

    /**
     * Read through an InputStream and returns the digest for the data
     *
     * @param digest
     *            The MessageDigest to use (e.g. MD5)
     * @param data
     *            Data to digest
     * @return the digest
     * @throws IOException
     *             On error reading from the stream
     */
    private static byte[] digest(final MessageDigest digest, final InputStream data) throws IOException {
        return updateDigest(digest, data).digest();
    }

    /**
     * Returns a <code>MessageDigest</code> for the given <code>algorithm</code>.
     *
     * @param algorithm
     *            the name of the algorithm requested. See <a
     *            href="http://docs.oracle.com/javase/6/docs/technotes/guides/security/crypto/CryptoSpec.html#AppA"
     *            >Appendix A in the Java Cryptography Architecture Reference Guide</a> for information about standard
     *            algorithm names.
     * @return A digest instance.
     * @see MessageDigest#getInstance(String)
     * @throws IllegalArgumentException
     *             when a {@link NoSuchAlgorithmException} is caught.
     */
    public static MessageDigest getDigest(final String algorithm) {
        try {
            return MessageDigest.getInstance(algorithm);
        } catch (final NoSuchAlgorithmException e) {
            throw new IllegalArgumentException(e);
        }
    }

    /**
     * Returns an MD2 MessageDigest.
     *
     * @return An MD2 digest instance.
     * @throws IllegalArgumentException
     *             when a {@link NoSuchAlgorithmException} is caught, which should never happen because MD2 is a
     *             built-in algorithm
     * @see MessageDigestAlgorithms#MD2
     * @since 1.7
     */
    public static MessageDigest getMd2Digest() {
        return getDigest(MessageDigestAlgorithms.MD2);
    }

    /**
     * Returns an MD5 MessageDigest.
     *
     * @return An MD5 digest instance.
     * @throws IllegalArgumentException
     *             when a {@link NoSuchAlgorithmException} is caught, which should never happen because MD5 is a
     *             built-in algorithm
     * @see MessageDigestAlgorithms#MD5
     */
    public static MessageDigest getMd5Digest() {
        return getDigest(MessageDigestAlgorithms.MD5);
    }

    /**
     * Returns an SHA-1 digest.
     *
     * @return An SHA-1 digest instance.
     * @throws IllegalArgumentException
     *             when a {@link NoSuchAlgorithmException} is caught, which should never happen because SHA-1 is a
     *             built-in algorithm
     * @see MessageDigestAlgorithms#SHA_1
     * @since 1.7
     */
    public static MessageDigest getSha1Digest() {
        return getDigest(MessageDigestAlgorithms.SHA_1);
    }

    /**
     * Returns an SHA-256 digest.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @return An SHA-256 digest instance.
     * @throws IllegalArgumentException
     *             when a {@link NoSuchAlgorithmException} is caught, which should never happen because SHA-256 is a
     *             built-in algorithm
     * @see MessageDigestAlgorithms#SHA_256
     */
    public static MessageDigest getSha256Digest() {
        return getDigest(MessageDigestAlgorithms.SHA_256);
    }

    /**
     * Returns an SHA-384 digest.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @return An SHA-384 digest instance.
     * @throws IllegalArgumentException
     *             when a {@link NoSuchAlgorithmException} is caught, which should never happen because SHA-384 is a
     *             built-in algorithm
     * @see MessageDigestAlgorithms#SHA_384
     */
    public static MessageDigest getSha384Digest() {
        return getDigest(MessageDigestAlgorithms.SHA_384);
    }

    /**
     * Returns an SHA-512 digest.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @return An SHA-512 digest instance.
     * @throws IllegalArgumentException
     *             when a {@link NoSuchAlgorithmException} is caught, which should never happen because SHA-512 is a
     *             built-in algorithm
     * @see MessageDigestAlgorithms#SHA_512
     */
    public static MessageDigest getSha512Digest() {
        return getDigest(MessageDigestAlgorithms.SHA_512);
    }

    /**
     * Returns an SHA-1 digest.
     *
     * @return An SHA-1 digest instance.
     * @throws IllegalArgumentException
     *             when a {@link NoSuchAlgorithmException} is caught
     * @deprecated Use {@link #getSha1Digest()}
     */
    @Deprecated
    public static MessageDigest getShaDigest() {
        return getSha1Digest();
    }

    /**
     * Calculates the MD2 digest and returns the value as a 16 element <code>byte[]</code>.
     *
     * @param data
     *            Data to digest
     * @return MD2 digest
     * @since 1.7
     */
    public static byte[] md2(final byte[] data) {
        return getMd2Digest().digest(data);
    }

    /**
     * Calculates the MD2 digest and returns the value as a 16 element <code>byte[]</code>.
     *
     * @param data
     *            Data to digest
     * @return MD2 digest
     * @throws IOException
     *             On error reading from the stream
     * @since 1.7
     */
    public static byte[] md2(final InputStream data) throws IOException {
        return digest(getMd2Digest(), data);
    }

    /**
     * Calculates the MD2 digest and returns the value as a 16 element <code>byte[]</code>.
     *
     * @param data
     *            Data to digest; converted to bytes using {@link StringUtils#getBytesUtf8(String)}
     * @return MD2 digest
     * @since 1.7
     */
    public static byte[] md2(final String data) {
        return md2(StringUtils.getBytesUtf8(data));
    }

    /**
     * Calculates the MD2 digest and returns the value as a 32 character hex string.
     *
     * @param data
     *            Data to digest
     * @return MD2 digest as a hex string
     * @since 1.7
     */
    public static String md2Hex(final byte[] data) {
        return Hex.encodeHexString(md2(data));
    }

    /**
     * Calculates the MD2 digest and returns the value as a 32 character hex string.
     *
     * @param data
     *            Data to digest
     * @return MD2 digest as a hex string
     * @throws IOException
     *             On error reading from the stream
     * @since 1.7
     */
    public static String md2Hex(final InputStream data) throws IOException {
        return Hex.encodeHexString(md2(data));
    }

    /**
     * Calculates the MD2 digest and returns the value as a 32 character hex string.
     *
     * @param data
     *            Data to digest
     * @return MD2 digest as a hex string
     * @since 1.7
     */
    public static String md2Hex(final String data) {
        return Hex.encodeHexString(md2(data));
    }

    /**
     * Calculates the MD5 digest and returns the value as a 16 element <code>byte[]</code>.
     *
     * @param data
     *            Data to digest
     * @return MD5 digest
     */
    public static byte[] md5(final byte[] data) {
        return getMd5Digest().digest(data);
    }

    /**
     * Calculates the MD5 digest and returns the value as a 16 element <code>byte[]</code>.
     *
     * @param data
     *            Data to digest
     * @return MD5 digest
     * @throws IOException
     *             On error reading from the stream
     * @since 1.4
     */
    public static byte[] md5(final InputStream data) throws IOException {
        return digest(getMd5Digest(), data);
    }

    /**
     * Calculates the MD5 digest and returns the value as a 16 element <code>byte[]</code>.
     *
     * @param data
     *            Data to digest; converted to bytes using {@link StringUtils#getBytesUtf8(String)}
     * @return MD5 digest
     */
    public static byte[] md5(final String data) {
        return md5(StringUtils.getBytesUtf8(data));
    }

    /**
     * Calculates the MD5 digest and returns the value as a 32 character hex string.
     *
     * @param data
     *            Data to digest
     * @return MD5 digest as a hex string
     */
    public static String md5Hex(final byte[] data) {
        return Hex.encodeHexString(md5(data));
    }

    /**
     * Calculates the MD5 digest and returns the value as a 32 character hex string.
     *
     * @param data
     *            Data to digest
     * @return MD5 digest as a hex string
     * @throws IOException
     *             On error reading from the stream
     * @since 1.4
     */
    public static String md5Hex(final InputStream data) throws IOException {
        return Hex.encodeHexString(md5(data));
    }

    /**
     * Calculates the MD5 digest and returns the value as a 32 character hex string.
     *
     * @param data
     *            Data to digest
     * @return MD5 digest as a hex string
     */
    public static String md5Hex(final String data) {
        return Hex.encodeHexString(md5(data));
    }

    /**
     * Calculates the SHA-1 digest and returns the value as a <code>byte[]</code>.
     *
     * @param data
     *            Data to digest
     * @return SHA-1 digest
     * @deprecated Use {@link #sha1(byte[])}
     */
    @Deprecated
    public static byte[] sha(final byte[] data) {
        return sha1(data);
    }

    /**
     * Calculates the SHA-1 digest and returns the value as a <code>byte[]</code>.
     *
     * @param data
     *            Data to digest
     * @return SHA-1 digest
     * @throws IOException
     *             On error reading from the stream
     * @since 1.4
     * @deprecated Use {@link #sha1(InputStream)}
     */
    @Deprecated
    public static byte[] sha(final InputStream data) throws IOException {
        return sha1(data);
    }

    /**
     * Calculates the SHA-1 digest and returns the value as a <code>byte[]</code>.
     *
     * @param data
     *            Data to digest
     * @return SHA-1 digest
     * @deprecated Use {@link #sha1(String)}
     */
    @Deprecated
    public static byte[] sha(final String data) {
        return sha1(data);
    }

    /**
     * Calculates the SHA-1 digest and returns the value as a <code>byte[]</code>.
     *
     * @param data
     *            Data to digest
     * @return SHA-1 digest
     * @since 1.7
     */
    public static byte[] sha1(final byte[] data) {
        return getSha1Digest().digest(data);
    }

    /**
     * Calculates the SHA-1 digest and returns the value as a <code>byte[]</code>.
     *
     * @param data
     *            Data to digest
     * @return SHA-1 digest
     * @throws IOException
     *             On error reading from the stream
     * @since 1.7
     */
    public static byte[] sha1(final InputStream data) throws IOException {
        return digest(getSha1Digest(), data);
    }

    /**
     * Calculates the SHA-1 digest and returns the value as a <code>byte[]</code>.
     *
     * @param data
     *            Data to digest; converted to bytes using {@link StringUtils#getBytesUtf8(String)}
     * @return SHA-1 digest
     */
    public static byte[] sha1(final String data) {
        return sha1(StringUtils.getBytesUtf8(data));
    }

    /**
     * Calculates the SHA-1 digest and returns the value as a hex string.
     *
     * @param data
     *            Data to digest
     * @return SHA-1 digest as a hex string
     * @since 1.7
     */
    public static String sha1Hex(final byte[] data) {
        return Hex.encodeHexString(sha1(data));
    }

    /**
     * Calculates the SHA-1 digest and returns the value as a hex string.
     *
     * @param data
     *            Data to digest
     * @return SHA-1 digest as a hex string
     * @throws IOException
     *             On error reading from the stream
     * @since 1.7
     */
    public static String sha1Hex(final InputStream data) throws IOException {
        return Hex.encodeHexString(sha1(data));
    }

    /**
     * Calculates the SHA-1 digest and returns the value as a hex string.
     *
     * @param data
     *            Data to digest
     * @return SHA-1 digest as a hex string
     * @since 1.7
     */
    public static String sha1Hex(final String data) {
        return Hex.encodeHexString(sha1(data));
    }

    /**
     * Calculates the SHA-256 digest and returns the value as a <code>byte[]</code>.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @param data
     *            Data to digest
     * @return SHA-256 digest
     * @since 1.4
     */
    public static byte[] sha256(final byte[] data) {
        return getSha256Digest().digest(data);
    }

    /**
     * Calculates the SHA-256 digest and returns the value as a <code>byte[]</code>.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @param data
     *            Data to digest
     * @return SHA-256 digest
     * @throws IOException
     *             On error reading from the stream
     * @since 1.4
     */
    public static byte[] sha256(final InputStream data) throws IOException {
        return digest(getSha256Digest(), data);
    }

    /**
     * Calculates the SHA-256 digest and returns the value as a <code>byte[]</code>.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @param data
     *            Data to digest; converted to bytes using {@link StringUtils#getBytesUtf8(String)}
     * @return SHA-256 digest
     * @since 1.4
     */
    public static byte[] sha256(final String data) {
        return sha256(StringUtils.getBytesUtf8(data));
    }

    /**
     * Calculates the SHA-256 digest and returns the value as a hex string.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @param data
     *            Data to digest
     * @return SHA-256 digest as a hex string
     * @since 1.4
     */
    public static String sha256Hex(final byte[] data) {
        return Hex.encodeHexString(sha256(data));
    }

    /**
     * Calculates the SHA-256 digest and returns the value as a hex string.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @param data
     *            Data to digest
     * @return SHA-256 digest as a hex string
     * @throws IOException
     *             On error reading from the stream
     * @since 1.4
     */
    public static String sha256Hex(final InputStream data) throws IOException {
        return Hex.encodeHexString(sha256(data));
    }

    /**
     * Calculates the SHA-256 digest and returns the value as a hex string.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @param data
     *            Data to digest
     * @return SHA-256 digest as a hex string
     * @since 1.4
     */
    public static String sha256Hex(final String data) {
        return Hex.encodeHexString(sha256(data));
    }

    /**
     * Calculates the SHA-384 digest and returns the value as a <code>byte[]</code>.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @param data
     *            Data to digest
     * @return SHA-384 digest
     * @since 1.4
     */
    public static byte[] sha384(final byte[] data) {
        return getSha384Digest().digest(data);
    }

    /**
     * Calculates the SHA-384 digest and returns the value as a <code>byte[]</code>.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @param data
     *            Data to digest
     * @return SHA-384 digest
     * @throws IOException
     *             On error reading from the stream
     * @since 1.4
     */
    public static byte[] sha384(final InputStream data) throws IOException {
        return digest(getSha384Digest(), data);
    }

    /**
     * Calculates the SHA-384 digest and returns the value as a <code>byte[]</code>.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @param data
     *            Data to digest; converted to bytes using {@link StringUtils#getBytesUtf8(String)}
     * @return SHA-384 digest
     * @since 1.4
     */
    public static byte[] sha384(final String data) {
        return sha384(StringUtils.getBytesUtf8(data));
    }

    /**
     * Calculates the SHA-384 digest and returns the value as a hex string.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @param data
     *            Data to digest
     * @return SHA-384 digest as a hex string
     * @since 1.4
     */
    public static String sha384Hex(final byte[] data) {
        return Hex.encodeHexString(sha384(data));
    }

    /**
     * Calculates the SHA-384 digest and returns the value as a hex string.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @param data
     *            Data to digest
     * @return SHA-384 digest as a hex string
     * @throws IOException
     *             On error reading from the stream
     * @since 1.4
     */
    public static String sha384Hex(final InputStream data) throws IOException {
        return Hex.encodeHexString(sha384(data));
    }

    /**
     * Calculates the SHA-384 digest and returns the value as a hex string.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @param data
     *            Data to digest
     * @return SHA-384 digest as a hex string
     * @since 1.4
     */
    public static String sha384Hex(final String data) {
        return Hex.encodeHexString(sha384(data));
    }

    /**
     * Calculates the SHA-512 digest and returns the value as a <code>byte[]</code>.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @param data
     *            Data to digest
     * @return SHA-512 digest
     * @since 1.4
     */
    public static byte[] sha512(final byte[] data) {
        return getSha512Digest().digest(data);
    }

    /**
     * Calculates the SHA-512 digest and returns the value as a <code>byte[]</code>.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @param data
     *            Data to digest
     * @return SHA-512 digest
     * @throws IOException
     *             On error reading from the stream
     * @since 1.4
     */
    public static byte[] sha512(final InputStream data) throws IOException {
        return digest(getSha512Digest(), data);
    }

    /**
     * Calculates the SHA-512 digest and returns the value as a <code>byte[]</code>.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @param data
     *            Data to digest; converted to bytes using {@link StringUtils#getBytesUtf8(String)}
     * @return SHA-512 digest
     * @since 1.4
     */
    public static byte[] sha512(final String data) {
        return sha512(StringUtils.getBytesUtf8(data));
    }

    /**
     * Calculates the SHA-512 digest and returns the value as a hex string.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @param data
     *            Data to digest
     * @return SHA-512 digest as a hex string
     * @since 1.4
     */
    public static String sha512Hex(final byte[] data) {
        return Hex.encodeHexString(sha512(data));
    }

    /**
     * Calculates the SHA-512 digest and returns the value as a hex string.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @param data
     *            Data to digest
     * @return SHA-512 digest as a hex string
     * @throws IOException
     *             On error reading from the stream
     * @since 1.4
     */
    public static String sha512Hex(final InputStream data) throws IOException {
        return Hex.encodeHexString(sha512(data));
    }

    /**
     * Calculates the SHA-512 digest and returns the value as a hex string.
     * <p>
     * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
     * </p>
     *
     * @param data
     *            Data to digest
     * @return SHA-512 digest as a hex string
     * @since 1.4
     */
    public static String sha512Hex(final String data) {
        return Hex.encodeHexString(sha512(data));
    }

    /**
     * Calculates the SHA-1 digest and returns the value as a hex string.
     *
     * @param data
     *            Data to digest
     * @return SHA-1 digest as a hex string
     * @deprecated Use {@link #sha1Hex(byte[])}
     */
    @Deprecated
    public static String shaHex(final byte[] data) {
        return sha1Hex(data);
    }

    /**
     * Calculates the SHA-1 digest and returns the value as a hex string.
     *
     * @param data
     *            Data to digest
     * @return SHA-1 digest as a hex string
     * @throws IOException
     *             On error reading from the stream
     * @since 1.4
     * @deprecated Use {@link #sha1Hex(InputStream)}
     */
    @Deprecated
    public static String shaHex(final InputStream data) throws IOException {
        return sha1Hex(data);
    }

    /**
     * Calculates the SHA-1 digest and returns the value as a hex string.
     *
     * @param data
     *            Data to digest
     * @return SHA-1 digest as a hex string
     * @deprecated Use {@link #sha1Hex(String)}
     */
    @Deprecated
    public static String shaHex(final String data) {
        return sha1Hex(data);
    }

    /**
     * Updates the given {@link MessageDigest}.
     *
     * @param messageDigest
     *            the {@link MessageDigest} to update
     * @param valueToDigest
     *            the value to update the {@link MessageDigest} with
     * @return the updated {@link MessageDigest}
     * @since 1.7
     */
    public static MessageDigest updateDigest(final MessageDigest messageDigest, final byte[] valueToDigest) {
        messageDigest.update(valueToDigest);
        return messageDigest;
    }

    /**
     * Reads through an InputStream and updates the digest for the data
     *
     * @param digest
     *            The MessageDigest to use (e.g. MD5)
     * @param data
     *            Data to digest
     * @return the digest
     * @throws IOException
     *             On error reading from the stream
     * @since 1.8
     */
    public static MessageDigest updateDigest(final MessageDigest digest, final InputStream data) throws IOException {
        final byte[] buffer = new byte[STREAM_BUFFER_LENGTH];
        int read = data.read(buffer, 0, STREAM_BUFFER_LENGTH);

        while (read > -1) {
            digest.update(buffer, 0, read);
            read = data.read(buffer, 0, STREAM_BUFFER_LENGTH);
        }

        return digest;
    }

    /**
     * Updates the given {@link MessageDigest}.
     *
     * @param messageDigest
     *            the {@link MessageDigest} to update
     * @param valueToDigest
     *            the value to update the {@link MessageDigest} with;
     *            converted to bytes using {@link StringUtils#getBytesUtf8(String)}
     * @return the updated {@link MessageDigest}
     * @since 1.7
     */
    public static MessageDigest updateDigest(final MessageDigest messageDigest, final String valueToDigest) {
        messageDigest.update(StringUtils.getBytesUtf8(valueToDigest));
        return messageDigest;
    }
}

工具包的下载地址：https://files.cnblogs.com/files/zuosy/apache-commons-codec.zip

里面有源码包和jar包解压之后就能用

我的MD5工具类：

import java.util.Random;
import org.apache.commons.codec.digest.DigestUtils;

public class Md5Util {

    public static final char[] pool = {'a', 'b', 'c', 'd', 'e', 
            'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',
            'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 
            'z', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', 
            '1', '2', '3', '4', '5', '6', '7', '8', '9', '0'};
    
    /**
     * 测试方法
     * @param args
     */
    public static void main(String[] args) {
        System.out.println("WithoutSalt: " + md5("12345"));
        String salt = addSalt();//fg27xhnr2e9ph289yixpoxe8diqk9t87
        System.out.println("Salt: " + salt);
        System.out.println("AddSalt: " + md5AddSalt("12345", "fg27xhnr2e9ph289yixpoxe8diqk9t87"));
        //db628ea6a5b53d7ead65d79ab598fa3d
        //db628ea6a5b53d7ead65d79ab598fa3d
        
        /*----------------华丽的分割线--------------------*/
        String password = "HelloWorld";
        System.out.println("Password:" + password);
        String salty = addSalt();
        System.out.println("Salt:" + salty);
        String md5 = md5AddSalt(password, salty);
        System.out.println("MD5:" + md5);
        System.out.println("Check Result is:" + check(password, md5, salty));
    }
    
    /**
     * md5不加盐
     * @param password
     * @return
     */
    public static String md5(String password) {
        return DigestUtils.md5Hex(password);
    }
    
    
    /**
     * md5 加的随机盐  可能没用了
     * @param password
     * @return
     */
    public static String md5AddSalt(String password) {
        String salt = addSalt();
        return md5AddSalt(password, salt);
    }
    
    /**
     * md5 加固定盐
     * @param password
     * @param salt
     * @return
     */
    public static String md5AddSalt(String password, String salt) {
        String md5Password = DigestUtils.md5Hex(password);
        return DigestUtils.md5Hex(md5Password + salt);
    }
    
    /**
     * 随机盐
     * @return
     */
    public static String addSalt() {
        int saltLength = 32;//盐的长度
        StringBuffer sb = new StringBuffer();
        Random random = new Random();
        for(int i = 0; i < saltLength; i++) {
            sb.append(pool[random.nextInt(pool.length)]);
        }
        return sb.toString();
    }
    
    public static boolean check(String password, String md5, String salt) {
        String temp = md5AddSalt(password, salt);
        //System.err.println(temp);
        return md5.equals(temp);
    }
    
    /**
     * 这是一个正确的MD5加密算法
     */
//    public static void main(String[] args) throws Exception {
//        String str = "12345";
//        //通过信息招摇单例的构造函数获取
//        MessageDigest md5 = MessageDigest.getInstance("MD5");
//        //信息摘要对象是对字节数组进行摘要的，所以先获取字符串的字节数组
//        byte[] bytes = str.getBytes();
//        byte[] digest = md5.digest(bytes);
//        //把摘要数组中的每一个字节转换成16进制，并拼在一起就得到了MD5值。
//        String MD5 = "";
//        for(int i = 0; i < digest.length; i++) {
//            int j = digest[i];
//            j = j & 0x000000ff;
//            String s1 = Integer.toHexString(j);
//            if(s1.length() == 1) {
//                s1 = "0" + s1;
//            }
//            
//            MD5 += s1;
//        }
//    }
}

---

 加密那部分就那样了，反正我是实习会的不多。接下来写一个实例的md5校验

首先我们到tomcat官网上随便下载一个文件。

再点一下那个md5,会跳转到一个页面

 

所以我仍然借用那个工具类进行md5校验，代码如下：

    public static void main(String[] args) throws Exception {
        String md5Message = "2ac0885c3588e3d237a0e1590aa0fd56";
        File file = new File("C:\Users\Zuosy\Downloads\apache-tomcat-9.0.1-windows-x86.zip");
        //System.out.println(file.exists());
        FileInputStream in = new FileInputStream(file);
        InputStream data = new BufferedInputStream(in);
        long startTime = System.currentTimeMillis();
        String jiaoyan = DigestUtils.md5Hex(data);
        long endTime = System.currentTimeMillis();
        System.out.println(endTime - startTime);
        //System.out.println(jiaoyan);
        //System.out.println(md5Message);
        System.out.println(jiaoyan.equals(md5Message));
    }    

true就是没毛病。

这段代码很好理解，也不需要什么特别的注释，请忽视一些不重要的代码。

---

 补充：

文档：

 参考别人的代码写出来的：

    public static String md5(String key) {
        char hexDigits[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 
                'a', 'b', 'c', 'd', 'e', 'f'};
        try {
            byte[] inputBytes = key.getBytes();
            MessageDigest mdInst = MessageDigest.getInstance("MD5");
            mdInst.update(inputBytes);
            byte[] md = mdInst.digest();
            //转成32位字符串
            char[] str = new char[md.length * 2];
            int k = 0;
            for(int i = 0; i < md.length; i++) {
                byte byte0 = md[i];
                str[k++] = hexDigits[byte0 >>> 4 & 0xf];
                str[k++] = hexDigits[byte0 & 0xf];
            }
            return new String(str);
        } catch (NoSuchAlgorithmException nsae) {
            nsae.printStackTrace();
            return null;
        }
    }

 然后16位的和32位的md5让人泣不成声。。。