强制字符换行。
style="word-break:break-all;word-wrap:break-word";
C#版：

        //oldString：要换行的字符串，width：每行的字符宽度（字符个数），tolerance:最长的单词长度，以免单词被从中截断
        //spanWidth,每一行的宽度
        public static String GetMutilLineString(String oldString, Int32 width, Int32 tolerance, Int32 spanWidth)
        {
            if (oldString == null)
            {
                return null;
            }
            if (oldString.Trim() == String.Empty)
            {
                return String.Empty;
            }
            if (width <= 1)
            {
                width = 150;
            }
            Int32 iIndex = 0;
            Int32 iFindLen = 0;
            String strUnit = String.Empty;
            String strFind = String.Empty;
            String strReturn = String.Empty;
            String strTemp = String.Empty;
            Int32 iTolerance = (tolerance > 0) ? tolerance : 8;
            Int32 iTempIndex = -1;
            while (oldString.Length > width + iTolerance)
            {
                iFindLen = 2 * iTolerance;
                strFind = oldString.Substring(width - iTolerance, iFindLen);

                iIndex = strFind.LastIndexOf(",", iFindLen - 1);
                if (iIndex == -1)
                {
                    iIndex = strFind.LastIndexOf("'", iFindLen - 1);
                }
                if (iIndex == -1)
                {
                    iIndex = strFind.LastIndexOf(";", iFindLen - 1);
                }
                if (iIndex == -1)
                {
                    iIndex = strFind.LastIndexOf(".", iFindLen - 1);
                }
                if (iIndex == -1)
                {
                    iIndex = strFind.LastIndexOf(" ", iFindLen - 1);
                }
                if (iIndex == -1)
                {
                    iIndex = strFind.LastIndexOf("_", iFindLen - 1);
                }
                if (iIndex == -1)
                {
                    iIndex = strFind.LastIndexOf("-", iFindLen - 1);
                }
                if (iIndex == -1)
                {
                    strUnit = oldString.Substring(0, width);
                    oldString = oldString.Remove(0, width);
                }
                else
                {
                    strUnit = oldString.Substring(0, width - iTolerance + iIndex + 1);
                    oldString = oldString.Remove(0, width - iTolerance + iIndex + 1);
                }
                while (strUnit.IndexOf("\r\n") > -1)
                {
                    iTempIndex = strUnit.IndexOf("\r\n");
                    strTemp = strUnit.Substring(0, iTempIndex);
                    strReturn += String.Format("<tr width={0} style='word-wrap:break-word'><td>{1}</td></tr>", spanWidth, strTemp);
                    strUnit = strUnit.Remove(0, iTempIndex + 2);
                }

                strReturn += String.Format("<tr width={0} style='word-wrap:break-word'><td>{1}</td></tr>", spanWidth, strUnit);
            }
            while (oldString.IndexOf("\r\n") > -1)
            {
                iTempIndex = oldString.IndexOf("\r\n");
                strTemp = oldString.Substring(0, iTempIndex);
                strReturn += String.Format("<tr width={0} style='word-wrap:break-word'><td>{1}</td></tr>", spanWidth, strTemp);
                oldString = oldString.Remove(0, iTempIndex + 2);
            }
            strReturn += String.Format("<tr width={0} style='word-wrap:break-word'><td>{1}</td></tr>", spanWidth, oldString);

            strReturn = String.Format("<table>{0}</table>",strReturn);

            return strReturn;
        }