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Language: Java
Expertise: Intermediate
Jul 25, 2019
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Using Symbolic Links in Java

Symbolic links are a useful entity, with which you can introduce some kind of encapsulation. The Symbolic link can be created in a secure environment (ex: DMZ) where users can access with valid credentials.

This helps us to keep the real source safe and the original location hidden. The exposed location, in reality, maybe a virtual path that can be created based on various parameters such as login session, user credentials, etc.

Sample code:

import java.nio.file.*;
import java.io.*;

public class SymbolicLink
{
   public static void main(String args[])
   {
      SymbolicLink symbolicLink = new SymbolicLink();
      symbolicLink.proceed();
   }
   
   private void proceed()
   {
      //You can use a secure path here that may be exposed to external users, who may be autorized to perform changes
      //The path is referring to restrictedAccess folder and this folder can be provided access so that external users can access
      Path symbolicLinkName = Paths.get("/home/sridhar/restrictedAccess/SymLnkForSourceFile");
      //This is the source file for which the link is being established
      Path soruceName = Paths.get("/home/sridhar/SymbolicLink.java");
      
      try {
         Files.createSymbolicLink(symbolicLinkName, soruceName);
         System.out.println("SymbolicLink created for " + soruceName);
      }catch (IOException ioe) {
         System.err.println(ioe);
      }
   }
}

/*

Expected output:

Before execution:
[root@mypc]# ls -lrt
-rw-r--r-- 1 root root 1078 Jun 19 12:41 SymbolicLink.class
-rw-r--r-- 1 root root 1274 Jun 19 12:41 SymbolicLink.java

After execution:

[root@mypc]# java SymbolicLink
SymbolicLink created for /home/sridhar/SymbolicLink.java
[root@mypc]# ls -lrt
-rw-r--r-- 1 root root 1078 Jun 19 12:41 SymbolicLink.class
-rw-r--r-- 1 root root 1274 Jun 19 12:41 SymbolicLink.java
drwxr-xr-x 2 root root   33 Jun 19 12:42 restrictedAccess

Executing for a second time results in a exception:

[root@mypc]# java SymbolicLink
java.nio.file.FileAlreadyExistsException: /home/sridhar/restrictedAccess/SymLnkForSourceFile

*/
M S Sridhar
 
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