SHA1安全加密

package com.wjz.util;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class SHA1Util {

       public static String encrypt(String str){  
            if(str == null || str.length() == 0){  
                return null;  
            }  
            char hexDigits[] = {'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'};  
              
            try {  
                MessageDigest mdTemp = MessageDigest.getInstance("SHA1");  
                mdTemp.update(str.getBytes("UTF-8"));  
                  
                byte[] md = mdTemp.digest();  
                int j = md.length;  
                char buf[] = new char[j*2];  
                int k = 0;  
                for(int i =0;i<j;i++){  
                    byte byteO = md[i];  
                    buf[k++] = hexDigits[byteO >>> 4 & 0xf];  
                    buf[k++] = hexDigits[byteO & 0xf];  
                }  
                return new String(buf);  
            } catch (NoSuchAlgorithmException e) {  
                return null;  
            } catch (UnsupportedEncodingException e) {  
                return null;  
            }  
        }
}