原生Java實現SHA256算法

package sha256demo;

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

public class Sha256 {

	/**
	 * 利用java原生的類實現SHA256加密
	 * 
	 * @param str 加密後的報文
	 * @return
	 */
	public static String getSHA256(String str) {
		MessageDigest messageDigest;
		String encodestr = "";
		try {
			messageDigest = MessageDigest.getInstance("SHA-256");
			messageDigest.update(str.getBytes("UTF-8"));
			encodestr = byte2Hex(messageDigest.digest());
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		}
		return encodestr;
	}

	/**
	 * 將byte轉爲16進制
	 * 
	 * @param bytes
	 * @return
	 */
	private static String byte2Hex(byte[] bytes) {
		StringBuffer stringBuffer = new StringBuffer();
		String temp = null;
		for (int i = 0; i < bytes.length; i++) {
			temp = Integer.toHexString(bytes[i] & 0xFF);
			if (temp.length() == 1) {
				// 1獲得一位的進行補0操做
				stringBuffer.append("0");
			}
			stringBuffer.append(temp);
		}
		return stringBuffer.toString();
	}
}