java简单实现MD5算法

 

java 代码

package com.ctgusec.bean;

import java.security.MessageDigest;

/** */
/**
 * @author zhupan
 */
public class MD5 {
    private String inStr;

    private MessageDigest md5;

    /** */
    /**
     * Constructs the MD5 object and sets the string whose MD5 is to be
     * computed.
     *
     * @param inStr
     *            the <code>String</code> whose MD5 is to be computed
     */
    public MD5(String inStr) {
        this.inStr = inStr;
        try {
            this.md5 = MessageDigest.getInstance(" MD5 ");
        } catch (Exception e) {
            System.out.println(e.toString());
            e.printStackTrace();
        }
    }

    /** */
    /**
     * Computes the MD5 fingerprint of a string.
     *
     * @return the MD5 digest of the input <code>String</code>
     */
    public String compute() {
        // convert input String to a char[]
        // convert that char[] to byte[]
        // get the md5 digest as byte[]
        // bit-wise AND that byte[] with 0xff
        // prepend "0" to the output StringBuffer to make sure that we don't end
        // up with
        // something like "e21ff" instead of "e201ff"

        char[] charArray = this.inStr.toCharArray();

        byte[] byteArray = new byte[charArray.length];

        for (int i = 0; i < charArray.length; i++)
            byteArray[i] = (byte) charArray[i];

        byte[] md5Bytes = this.md5.digest(byteArray);

        StringBuffer hexValue = new StringBuffer();

        for (int i = 0; i < md5Bytes.length; i++) {
            int val = ((int) md5Bytes[i]) & 0xff;
            if (val < 16)
                hexValue.append(" 0 ");
            hexValue.append(Integer.toHexString(val));
        }

        return hexValue.toString();
    }

    public static void main(String[] args) {
        MD5 md5 = new MD5(" zhupan ");
        String postString = md5.compute();
        System.out.println(postString);
        if (postString.equals(" 11c454577d6f32b0f3b43fdbf83510a2 ")) {
            System.out.println(" true ");
        } else
            System.out.println(" false ");
    }
}