单向哈希函数 JAVA版本

这里只给出MD5的代码，其他SHA等请查看发布的电子书

package base_crypt;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class base_md5 {
	
	public static byte[] md5_hash(byte[] s_buf){
		MessageDigest md5;
		try {
			md5 = MessageDigest.getInstance("MD5");
			md5.update(s_buf);
			return md5.digest();
		} catch (NoSuchAlgorithmException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} 
		return null;
	}
	
	public static String md5_hash_hex_str(byte[] s_buf){
		byte[] d_buf = md5_hash(s_buf);
		return byte_2_hex_str(d_buf);
	}
	
	public static String md5_hash_hex_str(String s_buf){
		byte[] buf = s_buf.getBytes();
		byte[] d_buf = md5_hash(buf);
		return byte_2_hex_str(d_buf);
	}
	
	private static String byte_2_hex_str(byte[] buf){
		String result = "";
		String tmp = "";
		int len = buf.length;
		for(int i =0;i