统计指定内容的汉字个数：

String str = "北京欢迎你 hello welcome!";

int count=0;

Pattern pattern = Pattern.compile("[\u4e00-\u9fa5]");

char c[] = str.toCharArray();

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

	Matcher matcher = pattern.matcher(String.valueOf(c[i]));

	if(matcher.matches()){

		count++;

	}

}

System.out.println(count);