package com.common.util;

import java.security.MessageDigest;  
import java.security.NoSuchAlgorithmException;  
public class EncryptUtils {  
    /** 
     * Encrypt string using MD5 algorithm 
     */  
    public final static String encryptMD5(String source) {  
        if (source == null) {  
            source = "";  
        }  
        String result = "";  
        try {  
            result = encrypt(source, "MD5");  
        } catch (NoSuchAlgorithmException ex) {  
            // this should never happen  
            throw new RuntimeException(ex);  
        }  
        return result;  
    }
    /** 
     * Encrypt string using SHA algorithm
     */  
    public final static String encryptSHA(String source) {  
        if (source == null) {  
            source = "";  
        }  
        String result = "";
        try {  
            result = encrypt(source, "SHA");  
        } catch (NoSuchAlgorithmException ex) {  
            // this should never happen  
            throw new RuntimeException(ex);  
        }  
        return result;  
    }  
    /**
     * Encrypt string 
     */
    private final static String encrypt(String source, String algorithm)  
            throws NoSuchAlgorithmException {  
        byte[] resByteArray = encrypt(source.getBytes(), algorithm);  
        return toHexString(resByteArray);  
    }
    /** 
     * Encrypt byte array. 
     */  
    private final static byte[] encrypt(byte[] source, String algorithm)  
            throws NoSuchAlgorithmException {  
        MessageDigest md = MessageDigest.getInstance(algorithm);  
        md.reset();  
        md.update(source);  
        return md.digest();  
    }  
    /** 
     * Get hex string from byte array 
     */  
    private final static String toHexString(byte[] res) {  
        StringBuffer sb = new StringBuffer(res.length << 1);  
        for (int i = 0; i < res.length; i++) {  
            String digit = Integer.toHexString(0xFF & res[i]);  
            if (digit.length() == 1) {  
                digit = '0' + digit;  
            }  
            sb.append(digit);  
        }  
        return sb.toString().toUpperCase();  
    }  
    
    public static void main(String args[]){

//		System.out.println(EncryptUtils.encrypt("a", "MD5"));
		//md5加密看下面控制台输出
		System.out.println(EncryptUtils.encryptMD5("王伟我爱你"));
	}
}