java实现md5加密

package weather.util;

import java.security.MessageDigest;

public class Md5Util {

public static String MD5(String inStr) {
    MessageDigest md5 = null;
    try {
        md5 = MessageDigest.getInstance("MD5");
    } catch (Exception e) {
        System.out.println(e.toString());
        e.printStackTrace();
        return "";
    }
    char[] charArray = inStr.toCharArray();
    byte[] byteArray = new byte[charArray.length];

    for (int i = 0; i < charArray.length; i++)
    {
        byteArray[i] = (byte) charArray[i];
    }
    byte[] md5Bytes = 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();
}

// 可逆的加密算法
public static String KL(String inStr) {
    // String s = new String(inStr);
    char[] a = inStr.toCharArray();
    for (int i = 0; i < a.length; i++) {
        a[i] = (char) (a[i] ^ 't');
    }
    String s = new String(a);
    return s;
}

// 加密后解密
public static String JM(String inStr) {
    char[] a = inStr.toCharArray();
    for (int i = 0; i < a.length; i++) {
        a[i] = (char) (a[i] ^ 't');
    }
    String k = new String(a);
    return k;
}

// 测试主函数
public static void main(String args[]) {
    String s = new String("a");
    String a="a";
    System.out.println("原始：" + s);
    System.out.println("MD5后：" + MD5(s));
    System.out.println("MD5后再加密：" + KL(MD5(s)));
    System.out.println("解密为MD5后的：" + JM(KL(MD5(s))));
}
}

测试结果：

原始：a
MD5后：0cc175b9c0f1b6a831c399e269772661
MD5后再加密：DECAMDEBLGEGMMFBMCCFBBE
解密为MD5后的：0cc175b9c0f1b6a831c399e269772661

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