JAVA MD5 加密與解密

package test;

import java.security.MessageDigest;

public class Test {

    /*** 
     * MD5加碼 生成32位md5碼 
     */  
    public static String string2MD5(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 = ; i < charArray.length; i++)  
            byteArray[i] = (byte) charArray[i];  
        byte[] md5Bytes = md5.digest(byteArray);  
        StringBuffer hexValue = new StringBuffer();  
        for (int i = ; i < md5Bytes.length; i++){  
            int val = ((int) md5Bytes[i]) & ;  
            if (val < )  
                hexValue.append("0");  
            hexValue.append(Integer.toHexString(val));  
        }  
        return hexValue.toString();  

    }  

    /** 
     * 加密解密算法 執行一次加密，兩次解密 
     */   
    public static String convertMD5(String inStr){  

        char[] a = inStr.toCharArray();  
        for (int i = ; i < a.length; i++){  
            a[i] = (char) (a[i] ^ 't');  
        }  
        String s = new String(a);  
        return s;  

    }  

    // 測試主函數  
    public static void main(String args[]) {  
        String s = new String("tuang");  
        System.out.println("原始：" + s);  
        System.out.println("MD5後：" + string2MD5(s));  
        System.out.println("加密的：" + convertMD5(s));  
        System.out.println("解密的：" + convertMD5(convertMD5(s)));  

    }  

}