What does servletcontext getRealPath mean and when should I use it

Question

In the following snippet   ServletContext context   request getServletContext    String path   context getRealPath         What does   in the method getRealPath   represent  When should I use it

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A web application s context path is the directory that contains the web application s WEB-INF directory  It can be thought of as the  home  of the web app  Often  when writing web applications  it can be important to get the actual location of this directory in the file system  since this allows you to do things such as read from files or write to files   This location can be obtained via the ServletContext object s getRealPath   method  This method can be passed a String parameter set to File separator to get the path using the operating system s file separator      for UNIX      for Windows

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There is also a change between Java 7 and Java 8   Admittedly it involves the a deprecated call  but I had to add a     to get our program working   Here is the link discussing it Why does servletContext getRealPath returns null on tomcat 8

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Introduction  The ServletContext getRealPath   is intented to convert a web content path  the path in the expanded WAR folder structure on the server s disk file system  to an absolute disk file system path   The     represents the web content root  I e  it represents the web folder as in the below project structure   YourWebProject   -- src              -- web        -- META-INF             -- MANIFEST MF        -- WEB-INF             -- web xml        -- index jsp        -- login jsp          So  passing the     to getRealPath   would return you the absolute disk file system path of the  web folder of the expanded WAR file of the project  Something like  path to server work folder some war  which you should be able to further use in File or FileInputStream   Note that most starters don t seem to see realize that you can actually pass the whole web content path to it and that they often use  String absolutePathToIndexJSP   servletContext getRealPath         index jsp      Wrong    or even   String absolutePathToIndexJSP   servletContext getRealPath        index jsp      Wronger    instead of  String absolutePathToIndexJSP   servletContext getRealPath   index jsp       Right    Don t ever write files in there  Also note that even though you can write new files into it using FileOutputStream  all changes  e g  new files or edited files  will get lost whenever the WAR is redeployed  with the simple reason that all those changes are not contained in the original WAR file  So all starters who are attempting to save uploaded files in there are doing it wrong    Moreover  getRealPath   will always return null or a completely unexpected path when the server isn t configured to expand the WAR file into the disk file system  but instead into e g  memory as a virtual file system    getRealPath   is unportable  you d better never use it  Use getRealPath   carefully  There are actually no sensible real world use cases for it  Based on my 20 years of Java EE experience  there has always been another way which is much better and more portable than getRealPath     If all you actually need is to get an InputStream of the web resource  better use ServletContext getResourceAsStream   instead  this will work regardless of the way how the WAR is expanded  So  if you for example want an InputStream of index jsp  then do not do   InputStream input   new FileInputStream servletContext getRealPath   index jsp        Wrong    But instead do   InputStream input   servletContext getResourceAsStream   index jsp       Right    Or if you intend to obtain a list of all available web resource paths  use ServletContext getResourcePaths   instead   Set lt String gt  resourcePaths   servletContext getResourcePaths         You can obtain an individual resource as URL via ServletContext getResource    This will return null when the resource does not exist   URL resource   servletContext getResource path     Or if you intend to save an uploaded file  or create a temporary file  then see the below  See also  links   See also    getResourceAsStream   vs FileInputStream Recommended way to save uploaded files in a servlet application Simple ways to keep data on redeployment of Java EE 7 web application

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My Method    protected void processRequest HttpServletRequest request  HttpServletResponse response          throws ServletException  IOException        try           String path   request getRealPath   WEB-INF conf properties            Properties p   new Properties            p load new FileInputStream path             String StringConexion p getProperty  StringConexion            String User p getProperty  User            String Password p getProperty  Password              catch Exception e           String msg    Excepcion     e

[java] What does servletcontext.getRealPath("/") mean and when should I use it

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