encode and decode

package test;

/**
 * 
 * @author jzzhao
 * @date 2011-3-18 下午09:30:46
 */
class EscapeUnescape {
	public static String escape(String src) {
		int i;
		char j;
		StringBuffer tmp = new StringBuffer();
		tmp.ensureCapacity(src.length() * 6);

		for (i = 0; i < src.length(); i++) {

			j = src.charAt(i);

			if (Character.isDigit(j) || Character.isLowerCase(j)
					|| Character.isUpperCase(j))
				tmp.append(j);
			else if (j < 256) {
				tmp.append("\\");
				if (j < 16)
					tmp.append("0");
				tmp.append(Integer.toString(j, 16));
			} else {
				tmp.append("\\u");
				tmp.append(Integer.toString(j, 16));
			}
		}
		return tmp.toString();
	}

	public static String unescape(String src) {
		StringBuffer tmp = new StringBuffer();
		tmp.ensureCapacity(src.length());
		int lastPos = 0, pos = 0;
		char ch;
		while (lastPos < src.length()) {
			pos = src.indexOf("\\", lastPos);
			if (pos == lastPos) {
				if (src.charAt(pos + 1) == 'u') {
					ch = (char) Integer.parseInt(
							src.substring(pos + 2, pos + 6), 16);
					tmp.append(ch);
					lastPos = pos + 6;
				} else {
					ch = (char) Integer.parseInt(
							src.substring(pos + 1, pos + 3), 16);
					tmp.append(ch);
					lastPos = pos + 3;
				}
			} else {
				if (pos == -1) {
					tmp.append(src.substring(lastPos));
					lastPos = src.length();
				} else {
					tmp.append(src.substring(lastPos, pos));
					lastPos = pos;
				}
			}
		}
		return tmp.toString();
	}

	public static void main(String[] args) {
		//String tmp = "种好";
		//System.out.println("testing escape : " + tmp);
		//tmp = escape(tmp);
		//System.out.println(tmp);
//		System.out.println("testing unescape :" + tmp);
		System.out.println(unescape("\u66b4\u6da8\u8fc7\u540e\u662f\u8d44\u672c"));
	}
}