/*
 *    Copyright 2012-2013 The Haohui Network Corporation
 */
package com.haohui.common.utils;

/**
 * <pre>
 * 字符串辅助工具
 * </pre>
 * 
 * @project baidamei
 * @author cevencheng <cevencheng@gmail.com>
 * @create 2012-11-30 下午2:42:56
 */
public class StringTool {

	/**
	 *<b>截取指定字节长度的字符串，不能返回半个汉字</b>
	 *	例如：
	 *	如果网页最多能显示17个汉字，那么 length 则为 34
	 * StringTool.getSubString(str, 34);
	 * 
	 * @param str
	 * @param length
	 * @return
	 */
	public static String getSubString(String str, int length) {
		int count = 0;
		int offset = 0;
		char[] c = str.toCharArray();
		for (int i = 0; i < c.length; i++) {
			if (c[i] > 256) {
				offset = 2;
				count += 2;
			} else {
				offset = 1;
				count++;
			}
			if (count == length) {
				return str.substring(0, i + 1);
			}
			if ((count == length + 1 && offset == 2)) {
				return str.substring(0, i);
			}
		}
		return "";
	}
}