java读取文件大小详解编程语言

public static void main(String[] args) { 
        String src = "c://test.apk"; 
        File file = new File(src); 
        DecimalFormat df = new DecimalFormat("0.00"); 
        String fileSizeString = ""; 
         if (file.length() < 1024) { 
            fileSizeString = df.format((double) file.length()) + "B"; 
        } else if (file.length() < 1048576) { 
            fileSizeString = df.format((double) file.length() / 1024) + "K"; 
        } else if (file.length() < 1073741824) { 
            fileSizeString = df.format((double) file.length() / 1048576) + "M"; 
        } else { 
            fileSizeString = df.format((double) file.length() / 1073741824) + "G"; 
        } 
         System.out.println("==========>"+fileSizeString); 
    }