获取字符串中指定字符串出现的所有位置

        String path = "localhost:8080";
        String details = "<p><img src="/upload/5a52da4dN0a6d04b9.jpg!q701.jpg""></p>"
        
        StringBuilder sb = new StringBuilder(details);
        Pattern pattern = Pattern.compile("<img src=\"");  
        Matcher findMatcher = pattern.matcher(sb);  
        while(findMatcher.find()) {      //如果检索到则为true
            int i = findMatcher.start();    // i <img src=\" 每次检索到的下标
        }