我在服务器上有一个zip文件。
如何检查该文件大小是否大于27MB?
File file = new File("U:\intranet_root\intranet\R1112B2.zip");
if (file > 27) {
//do something
}
使用File
类的length()
方法返回文件以字节为单位的大小。
// Get file from file name
File file = new File("U:\intranet_root\intranet\R1112B2.zip");
// Get length of file in bytes
long fileSizeInBytes = file.length();
// Convert the bytes to Kilobytes (1 KB = 1024 Bytes)
long fileSizeInKB = fileSizeInBytes / 1024;
// Convert the KB to MegaBytes (1 MB = 1024 KBytes)
long fileSizeInMB = fileSizeInKB / 1024;
if (fileSizeInMB > 27) {
...
}
您可以将转换步骤合并为一步,但我已经尝试充分说明过程。尝试使用以下代码:
File file = new File("infilename");
// Get the number of bytes in the file
long sizeInBytes = file.length();
//transform in MB
long sizeInMb = sizeInBytes / (1024 * 1024);
示例:
public static String getStringSizeLengthFile(long size) {
DecimalFormat df = new DecimalFormat("0.00");
float sizeKb = 1024.0f;
float sizeMb = sizeKb * sizeKb;
float sizeGb = sizeMb * sizeKb;
float sizeTerra = sizeGb * sizeKb;
if(size < sizeMb)
return df.format(size / sizeKb)+ " Kb";
else if(size < sizeGb)
return df.format(size / sizeMb) + " Mb";
else if(size < sizeTerra)
return df.format(size / sizeGb) + " Gb";
return "";
}
最简单的方法是使用Apache commons-io中的FileUtils。( https://commons.apache.org/proper/commons-io/javadocs/api-2.5/org/apache/commons/io/FileUtils.html )
将文件大小从字节转换为艾克斯字节并四舍五入到边界,以人类可读的形式返回。
File fileObj = new File(filePathString);
String fileSizeReadable = FileUtils.byteCountToDisplaySize(fileObj.length());
// output will be like 56 MB
file.length()将返回文件大小(以字节为单位),您可以将其除以1048576,然后就得到了兆字节数!
自Java 7起,您可以使用java.nio.file.Files.size(Path p)
方法。
Path path = Paths.get("C:\\1.txt");
long expectedSizeInMB = 27;
long expectedSizeInBytes = 1024 * 1024 * expectedSizeInMB;
long sizeInBytes = -1;
try {
sizeInBytes = Files.size(path);
} catch (IOException e) {
System.err.println("Cannot get the size - " + e);
return;
}
if (sizeInBytes > expectedSizeInBytes) {
System.out.println("Bigger than " + expectedSizeInMB + " MB");
} else {
System.out.println("Not bigger than " + expectedSizeInMB + " MB");
}
public static String getSizeLabel(Integer size) {
String cnt_size = "0";
double size_kb = size / 1024;
double size_mb = size_kb / 1024;
double size_gb = size_mb / 1024;
if (Math.floor(size_gb) > 0) {
try {
String[] snplit = String.valueOf((size_gb)).split("\\.");
cnt_size = snplit[0] + "." + snplit[1].substring(0, 2) + "GB";
} catch (Exception e) {
cnt_size = String.valueOf(Math.round(size_gb)) + "GB";
}
} else if (Math.floor(size_mb) > 0) {
try {
String[] snplit = String.valueOf((size_mb)).split("\\.");
cnt_size = snplit[0] + "." + snplit[1].substring(0, 2) + "MB";
} catch (Exception e) {
cnt_size = String.valueOf(Math.round(size_mb)) + "MB";
}
} else {
cnt_size = String.valueOf(Math.round(size_kb)) + "KB";
}
return cnt_size;
}
如何使用:
Integer filesize = new File("path").length();
getSizeLabel(filesize) // Output 16.02MB
将以下代码添加到任意位置,然后调用if (myFile.sizeInMb > 27.0)
或其他所需条件:
val File.size get() = if (!exists()) 0.0 else length().toDouble()
val File.sizeInKb get() = size / 1024
val File.sizeInMb get() = sizeInKb / 1024
val File.sizeInGb get() = sizeInMb / 1024
val File.sizeInTb get() = sizeInGb / 1024
如果你希望更轻松地处理字符串或Uri,请尝试添加以下内容:
fun Uri.asFile(): File = File(toString())
fun String?.asUri(): Uri? {
try {
return Uri.parse(this)
} catch (e: Exception) {
}
return null
}
如果您想将这些值轻松地显示为字符串,这些是简单的包装器。可以自由定制默认显示的小数位数。
fun File.sizeStr(): String = size.toString()
fun File.sizeStrInKb(decimals: Int = 0): String = "%.${decimals}f".format(sizeInKb)
fun File.sizeStrInMb(decimals: Int = 0): String = "%.${decimals}f".format(sizeInMb)
fun File.sizeStrInGb(decimals: Int = 0): String = "%.${decimals}f".format(sizeInGb)
fun File.sizeStrWithBytes(): String = sizeStr() + "b"
fun File.sizeStrWithKb(decimals: Int = 0): String = sizeStrInKb(decimals) + "Kb"
fun File.sizeStrWithMb(decimals: Int = 0): String = sizeStrInMb(decimals) + "Mb"
fun File.sizeStrWithGb(decimals: Int = 0): String = sizeStrInGb(decimals) + "Gb"
public static long sizeOf(File file)
有关 API 的更多信息:http://commons.apache.org/proper/commons-io/apidocs/org/apache/commons/io/FileUtils.html