public static void main(String[] args) {/*** String 常用API* 字符串*   1>截取*   2>替换**/String fileSuffix = ".jpg";int i = fileSuffix.indexOf(".");//截取.之后的内容，包含. indexs+0String newStr = fileSuffix.substring(i+ 0);//截取.之后的内容，不包含. indexs+1String newStr2 = fileSuffix.substring(i + 1);System.out.println("包含.   :"+newStr);System.out.println("不包含.  :"+newStr2);String separator = "webapps\\com\\gblfy";System.out.println("将.替换为@   :"+fileSuffix.replace(".","@"));System.out.println("将双\\替换为单/ :"+separator.replace("\\","/"));}