xml字符串格式化

	/**
	<b><b>    \r\n(+\t)
	</b><b>   \r\n
	</b></b>  \r\n(-\t)
	/><b>     \r\n
	/></b>    \r\n(-\t)
	 */
	public static void show(String xml) {
		Matcher mth = Pattern.compile("(?:<\\w+>\\s*<\\w+|</\\w+>\\s*<.|/>\\s*<.)").matcher(xml);
		int count = 0;
		StringBuffer sb = new StringBuffer();
		char[] cs = "\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t".toCharArray();
		int lastEnd = 0;
		while (mth.find(lastEnd)) {
			try {
				String str = mth.group();
				int idx2 = str.indexOf('<',1);
				if (str.charAt(0) == '<' && str.charAt(1) != '/') {
					count++;
				} else if (str.charAt(0) == '<' && str.charAt(1) == '/') {
					if (str.charAt(idx2 + 1) == '/') {
						count--;
					}
				} else if (str.charAt(0) == '/') {
					if (str.charAt(idx2 + 1) == '/') {
						count--;
					}
				}
				sb.append(xml,lastEnd,mth.start() + str.indexOf('>') + 1).append("\r\n").append(cs,count);
				lastEnd = mth.start() + idx2;
			} catch (Exception e) {
				throw new RuntimeException(count + "," + lastEnd + "," + sb + "--",e);
			}
		}
		sb.append(xml,xml.length());
		System.out.println(sb);
	}

(?:) 非获取匹配，不进行存储供以后使用，预查消耗字符

(?=) 正向预查，预查不消耗字符，