//用内存，将小写字母替换成大写字母
		String str = "helloworld,goodmorning";
		ByteArrayOutputStream bos = null;
		ByteArrayInputStream bis = null;
		bis = new ByteArrayInputStream(str.getBytes());
		bos = new ByteArrayOutputStream();
		int temp = -1;
		while( (temp = bis.read()) != -1 ) //依次读取内存
		{
                         //接收字符
			char c = (char) temp;
			bos.write(Character.toUpperCase(c)); //输出
		}
		//取出内存中的内容
		String newStr = bos.toString();
		System.out.println(newStr);