java 正則匹配開頭和結尾字符串，中間為固定個數的字符

public class TestDemo {

	public static void main(String[] args) {
		//匹配以∈{開頭，中間7個字符 ，以}∈結尾的字符串 
		boolean isMatch1 = Pattern.matches("^∈\\{+.{7}\\}∈$", "∈{ddddddd}∈");
		System.out.println(isMatch1);

		boolean isMatch = Pattern.matches("^∞+.{7}∞$", "∞ddddddd∞");

		// .為任意字符串， "^∞+\\d{7}∞$" 表示中間7位字符必須為數字
		Pattern p = Pattern.compile("^∞+.{7}∞$");
		Matcher matcher = p.matcher("∞1212a21∞");
		System.out.println(matcher.find());
	}

}