thymeleaf操作字符串
${#strings.startsWith(str,'o')}
${#strings.endsWith(str, 's')}
${#strings.indexOf(str,frag)}
${#strings.substring(str,3,5)}
${#strings.substringAfter(str,prefix)}
${#strings.substringBefore(str,suffix)}
${#strings.replace(str,'las','ler')}
${#strings.prepend(str,prefix)}
${#strings.append(str,suffix)}
${#strings.toUpperCase(str)}
${#strings.toLowerCase(str)}
${#strings.trim(str)}
${#strings.length(str)}
${#strings.abbreviate(str,10)}