Java files File Operation summary __java

Because the Java file feature has been in use, but it's always confusing, today is a summary of all the features of Java file.

Java file Operations I personally think that the important issues are:

A: How to cross platform issues
B: File coding issues, especially how to work properly in the case of multi-language platforms.
C: File read and write efficiency, operational efficiency
D: File encryption and file security
E: File fast retrieval, it is strongly recommended to use Lence for file retrieval and file management.

Here are some of my finishing:

One: Create a document

File File1 = new file ("C://temp//mynote.txt"); In Windows this is the method under Windows file system
File File2 = new file ("/tmp/mynote.txt"); In Linux/unix Unix file system methods

The safest way to create a file:

File MyFile = new file ("C:" + file.separator + "jdk1.5.0" + file.separator, "File.java");

File.separator is a file path symbol.
System.out.println (Myfile.getname ());//Get File name method
System.out.println (Myfile.getpath ());//method of obtaining file path
System.out.println (Myfile.isabsolute ())//To determine whether the file is complete
System.out.println (Myfile.getparent ());//Get the root directory of the file
System.out.println (Myfile.exists ())//To determine whether the file exists
System.out.println (Myfile.isdirectory ());//Judge whether it is a directory
System.out.println (Myfile.isfile ());//Judge whether it is a file
System.out.println (Myfile.ishidden ());//Determine if the file is hidden
System.out.println (Myfile.canread ())//To determine whether it is readable
System.out.println (Myfile.canwrite ());//To determine whether or not to write

File Myfile_a = new file ("C:" + file.separator);
For (String s:myfile_a.list ()) {//Read all files under a directory
System.out.println (s);
}

File Myfile_c=new file ("D:/test.txt");
System.out.println (New Date (Myfile_c.lastmodified ()))//Last Edit time
Myfile_c.renameto (New File ("C:/text.txt.bak"));//from named
Myfile_c.setreadonly ()//set to read-only
Second: File Filtering method

Java provides a good excuse for file filtering: FilenameFilter Filtered files can be displayed with Listfiles. The efficiency is still very high.

Import Java.io.File;
Import Java.io.FilenameFilter;
Import Java.util.Date;
/**
* File filter Filter class
* @author FB
*/
Class Filelistfilter implements FilenameFilter {
private String name;
Private String extension;
Public Filelistfilter (string name, String extension) {
THIS.name = name;
this.extension = extension;
}
Public Boolean accept (File directory, String filename) {
Boolean fileok = true;
if (name!= null) {
FileOK = Filename.startswith (name);
}
if (extension!= null) {
FileOK = Filename.endswith ('. ' + extension);
}
return fileok;
}
}
Test method:

Import Java.io.File;
Import Java.io.FilenameFilter;
Import Java.util.Date;
/**
* File filter Run function
* @author FB
*/
public class Run_filelistfilter {
public static void Main (string[] args) {
File Mydir = new file ("d:/");
FilenameFilter select = New Filelistfilter ("F", "txt");
file[] Contents = mydir.listfiles (select);
for (File file:contents) {
System.out.println (file + "is a" + (File.isdirectory ()?) Directory ":" File ")
+ "Last modified on/n" + New Date (File.lastmodified ()));
}
}
}
Third: Create directories, files, temporary files, delete files or directories
Import Java.io.File;
Import java.io.IOException;

public class MakeDir {

public static void Main (string[] args) {
File Myfile=new file ("d:/myfubin/");
if (Myfile.mkdir ()) {//single level directory
SYSTEM.OUT.PRINTLN ("Create directory Success");
}else{
SYSTEM.OUT.PRINTLN ("Build directory Failed");
}

File Myfile_a=new file ("d:/myfubin/test/");
if (Myfile_a.mkdirs ()) {//Multilevel directory
SYSTEM.OUT.PRINTLN ("Create directory Success");
}else{
SYSTEM.OUT.PRINTLN ("Build directory Failed");
}

File File = new file ("D://myfubin//test.txt");
try {
File.createnewfile ()//Create an empty file
catch (IOException e) {
E.printstacktrace ();
}

System.out.println (File.canread ());

if (File.delete ()) {//delete file or delete directory
Another way to delete a file: File.deleteonexit () This method is to delete the file when the program exits
System.out.println ("delete succeeded");
}else{
System.out.println ("delete failed");
}

try {
File TMP = file.createtempfile ("foo", "tmp");//Create temporary files
System.out.println ("The temporary document just established in:" + Tmp.getcanonicalpath ());
catch (IOException e) {
E.printstacktrace ();
}


}

}

Import Java.io.File;
/**
* @author fb  www.cujava.com
* File Operation Java 1.6 new features: Query disk space
*/
public class Spacechecker {

  public static void Main (string[] args) {
  file[] roots = file.listroots ()//Get all the roots, If it is a Windows system then it will get all the disks
      for (int i = 0; i < roots.length; i++) {
     &NB Sp  system.out.println (Roots[i]);
        system.out.println ("free spaces =" + roots[i].getfreespace ());
        system.out.println ("Usable space =" + Roots[i].getusablespace ());
       &NBSP;SYSTEM.OUT.PRINTLN ("total spaces =" + roots[i].gettotalspace ());
        system.out.println ();
      }
  }
}