Spring MVC-无法在webapp / resources /中创建文件

Question

I want to create file at 'webapp/resources/'

I used following code.

String filepath = "classpath:webapp/resources/" + filename +".json";
File file = new File(filepath);

if (!file.exists()) {

            file.createNewFile();
}

but error occured.

ex) no such file or directory

I think file path is incorrect.

I don't know real path of '/webapp/resources/'.

Answer 1

You have to get Physical Path from Servlet Context like

   //add HttpServletRequest request in spring controller as parameter
   String phyPath = request.getSession().getServletContext().getRealPath("/");

   String filepath = phyPath + "resources/" + filename +".json";
   File file = new File(filepath);
   if (!file.exists()) {
            file.createNewFile();
   }

Be carefull before using it because after project re-deloyed,it will be flushed. Other better option is to create CDN(Content Delivery Network) like server and store file there.

Answer 2

java.io.File knows nothing about classpath: prefix. It passes profided filepath directly to OS system function. And filepath is treated verbatim. So you get error because there is no file with path classpath:webapp/resources/blah-blab.json .

One of your options is to use getRealPath . But this is not portable and depends on how your application is deployed and what application server is used. In some cases application deployed as war is not unpacked, it is also possible that application is unpacked to temporary folder which is cleared between application server reboot. In general this behavior is application server specific and should not be relied on.