工具方法

1.查询文件内容字节长度
public class Demo {

    public static void main(String[] args) throws ParseException, IOException {

        FileInputStream fileInputStream = new FileInputStream("D:\\Desktop\\aa.txt");
        System.out.println(contentLength(fileInputStream));

    }

    public static long contentLength(InputStream is) throws IOException {

        try {
            long size = 0;
            byte[] buf = new byte[256];
            int read;
            while ((read = is.read(buf)) != -1) {
                size += read;
            }
            return size;
        }
        finally {
            try {
                is.close();
            }
            catch (IOException ex) {
            }
        }
    }
}
2. 从给定的字符中删除任意字符

public static String deleteAny(String inString, @Nullable String charsToDelete) {
        if (!hasLength(inString) || !hasLength(charsToDelete)) {
            return inString;
        }

        StringBuilder sb = new StringBuilder(inString.length());
        for (int i = 0; i < inString.length(); i++) {
            char c = inString.charAt(i);
            if (charsToDelete.indexOf(c) == -1) {
                sb.append(c);
            }
        }
        return sb.toString();
}