用Java检查服务器上文件的最后修改
在Java中,我们有不同的类,如 File、URL,它们提供读取文件属性的功能,如创建时间、上次访问时间和上次修改时间。
方法一(使用BasicFileAttributes)
本示例使用Java.nio.*来显示文件的元数据和其他文件属性,如创建时间、上次访问时间和上次修改时间。
Java
// Java Program to get last modification time of the file
import java.io.IOException;
import java.net.HttpURLConnection;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.BasicFileAttributes;
public class GFG {
public static void main(String args[])
{
// storing the path of the file in the string
String fileName = "C:/Users/elavi/Desktop/File.txt";
// used exception handling in order to catch the
// exception
// which may occur if there is no such file is
// present at specified location
// or the path of the file provided by the user is
// incorrect
try {
// getting the path of the file
Path file = Paths.get(fileName);
// reading the attributes of the file
BasicFileAttributes attr = Files.readAttributes(
file, BasicFileAttributes.class);
// getting the last modification time of the
// file
System.out.println(
"lastModifiedTime of File Is : "
+ attr.lastModifiedTime());
}
catch (IOException e) {
e.printStackTrace();
}
}
}
Java
// Java Program to get last modification time of the file
import java.io.File;
import java.text.SimpleDateFormat;
public class GFG_Article {
public static void main(String[] args)
{
// path of the file
String fileName = "C:/Users/elavi/Desktop/File.txt";
File file = new File(fileName);
// getting the last modified time of the file in the
// raw format ie long value of milliseconds
System.out.println("Before Format : "
+ file.lastModified());
// getting the last modified time of the file in
// terms of time and date
SimpleDateFormat sdf
= new SimpleDateFormat("MM/dd/yyyy HH:mm:ss");
System.out.println(
"The Date and Time at which the file was last modified is "
+ sdf.format(file.lastModified()));
}
}
Java
// Java Program to get last modification time of the file
import java.net.URL;
import java.net.URLConnection;
import java.util.Calendar;
import java.util.Date;
public class GFG {
public static void main(String[] args) throws Exception
{
// resource url
URL u = new URL(
"https://www.geeksforgeeks.org/file-handling-java-using-filewriter-filereader/");
URLConnection uc = u.openConnection();
uc.setUseCaches(false);
// getting the last modified time of the file
// uploaded on the server
long timestamp = uc.getLastModified();
System.out.println(
"The last modification time of java.bmp is :"
+ timestamp);
}
}
输出:输出包含文件中最后一次修改的日期和时间。
方法二(使用 File.lastModified)
对于legacy IO,可以使用File.lastModified() 方法来获取文件的最后修改时间,该函数返回文件的最后修改时间,以毫秒为单位的long值。我们可以使用 SimpleDataFormat 类使返回的结果更具可读性。
Java
// Java Program to get last modification time of the file
import java.io.File;
import java.text.SimpleDateFormat;
public class GFG_Article {
public static void main(String[] args)
{
// path of the file
String fileName = "C:/Users/elavi/Desktop/File.txt";
File file = new File(fileName);
// getting the last modified time of the file in the
// raw format ie long value of milliseconds
System.out.println("Before Format : "
+ file.lastModified());
// getting the last modified time of the file in
// terms of time and date
SimpleDateFormat sdf
= new SimpleDateFormat("MM/dd/yyyy HH:mm:ss");
System.out.println(
"The Date and Time at which the file was last modified is "
+ sdf.format(file.lastModified()));
}
}
输出:输出包含文件中最后一次修改的日期和时间。
方法三(使用 URL 类)
检查最后 修改 上传文件在服务器上的时间,我们可以利用 URL 类,然后可以获取文件的最后修改时间。
Java
// Java Program to get last modification time of the file
import java.net.URL;
import java.net.URLConnection;
import java.util.Calendar;
import java.util.Date;
public class GFG {
public static void main(String[] args) throws Exception
{
// resource url
URL u = new URL(
"https://www.geeksforgeeks.org/file-handling-java-using-filewriter-filereader/");
URLConnection uc = u.openConnection();
uc.setUseCaches(false);
// getting the last modified time of the file
// uploaded on the server
long timestamp = uc.getLastModified();
System.out.println(
"The last modification time of java.bmp is :"
+ timestamp);
}
}
输出