I have a simple java web application with following folder structure.
When I deploy the web app it has data.json file in WEB-INF/classes folder. I need to write data to this file from controller.java class controller package which is in WEB-INF/classes folder.
I tried following code.
FileOutputStream output = new FileOutputStream("..\\data.json", true);
output.write(jsonObject.toJSONString().getBytes());
output.flush();
This doesn't give me any error which suggest that the operation happen in a file somewhere in my computer.
How can I write to the data.json file? I can't give absolute path here.
WEB-INF/classes is for the class-path. Files there should be considered read-only, cacheable resources (getResource, getResourceAsStream).
The HttpRequest.getServletContext().getRealPath("/WEB-INF") can be used,
for file system paths.
I suggest using the classes files as template, copied the first time to a real file system path, and then being overwritten.
Use /, not Windows \\.
Use close() and then flush() is not needed.
Use getBytes(StandardCharsets.UTF_8).
Following code worked,
FileOutputStream output = new FileOutputStream( request.getSession().getServletContext().getRealPath("WEB-INF/classes/data.json"), false);
Related
I'm trying to read a text file located in src/main/resources/test/file.txt. I'm trying to get the path of the file using String path = getClass().getResource("/text/file.txt").getFile(); but when I try to read it I get a FileNotFoundException. I tried putting many different paths, all of which failed. How can I go about doing this?
The idea of putting something into the src/main/resources tree is that it will be copied into the JAR file that you build from your project. It will then be available to your application via the Class methods getResource(String) and getResourceAsStream(String) methods.
When you are running in your application in the development environment, it is certainly possible to use FileInputStream etcetera to access the resource. But this won't work in production. In production, the resources will then be inside your app's JAR file. FileInputStream cannot open a JAR file and its contents by name.
When you do this:
getClass().getResource("/text/file.txt");
you get a URL for the resource, which will look something like this:
jar:file:/path/to/your.jar!/text/file.txt"
It is not possible to turn that into a pathname the FileInputStream will understand. Whatever you try will give you a FileNotFoundException ... or something that is not the resource you want to read.
So what to do?
You have a few options, depending on your application's requirements.
You can use getResourceAsStream and use the resulting input stream directly.
You can copy the contents of getResourceAsStream to a temporary file, and then use the pathname of the temporary file.
You can create an application specific directory (e.g. in the user's home directory) and extract the file you need from the JAR into the directory. You might do this the first time the application runs.
You could open the JAR file as a JarFile and use that API to open an InputStream for the resource. But this assumes that that the resources are in a JAR ... and on some platforms (e.g. Windows) you may encounter problems with file locking. (And it would be a bad idea to attempt to update the resource in the JAR.)
Try giving complete path of the file from the disk.
C:\Users\MyUser\Desktop\file name with extension
I am working on a SpringMVC project which runs a number of automated tests on a database. The access details for this database are located in a .properties file. This file is located within the project directory.
FileInputStream fis = new FileInputStream("batch-dm.properties");
propFile = new Properties();
propFile.load(fis);
As the file is stored in the project directory the FileInputStream should be able to access it no?
If I provide the absolute path e.g.
FileInputStream fis = new FileInputStream("C:/workspace/Project/batch-dm.properties");
It recognises the file and runs properly.
Do I need to sore this file in a different location because it is a Spring MVC project?
Thanks
Just to clear out your mind, try to see what is the value that outputs System.getProperty("user.dir") (let's call it A), this will print the complete absolute path from where your application was initialized, more specifically it will print the directory from where the JVM was started.
If you doesn't supply a parent path to the file that you are trying to open, the (A) path is taken by default and the file is looked inside that directory. So please, have in mind that.
Aditional information
If you absolutely need that file you should include it in your project so you can access it as a resource. Resource is a file that is included in your project and came bundled with the generated .jar or .war for re distribution.
My advice is to put the file in the package and use as a resource as it the safer way to work with external resources that should be shipped with your project.
Take a deeper look at this post for more about practical way of handling resources.
Please refer below link:
https://stackoverflow.com/a/2308388/1358551
You may have to use getResourceAsStream().
FileWriter out = new Filewriter("/textfile.txt");
out.write("Hello");
out.close();
But unable to write into the file(file located inside the webcontent folder of my project)
This is not a very good approach. Apart from relying on the fact that the web application is exploded by the container (as opposed to being served from the WAR file directly), it makes it tricky to deploy new versions of the app (you have to make sure not to clobber those generated files).
If you must do something like this, choose a different directory outside of the web application, set the path to that directory as configuration to your app and write the files there. You can then configure the web server to mount that directory into your URL space (so that it will look the same to browsers).
Though Thilo's comments right. But if you really want to do then try this one.
//Suppose if it is on root webcontent folder
FileWriter out = new Filewriter("textfile.txt");
out.write("Hello");
out.close();
But if it is in some other folder within root webcontect folder then try this e.g. If file is in File folder then.
FileWriter out = new Filewriter("File/textfile.txt");
out.write("Hello");
out.close();
I have a Java application in Eclipse that references .XML files as templates for other functionality. Usually I package the .JAR file without these files, because placing them within the same folder as the .JAR file seems to work fine with this reference:
File myFile = new File("templates/templateA.xsd");
I now require that these templates be placed within the same .JAR file as this application. I can include them with no problems, but these references no longer seem to work.
Is there a correct way of referencing the .XML file from within the same .JAR that the application is running from?
You need to know how to load the files from class path.
one of the ways is as follows
class XMLLoader {
public String loadXML(String fileName){
InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream(fileName);
// do the loading of the file from the given input stream.
}
}
you know that the "templates" folder should be inside of your jar.
If you just need to read this file, you might not need a java.io.File but just an InputStream that you can get via
this.getClass().getResourceAsStream("templates/templateA.xsd")
If you really need a java.io.File... I do not know... The last time a really needed a File, I just copied the InputStream to a temporary file but this is ugly.
I'm programming Java in Eclipse IDE. Here is code I want to read file:
File file = new File("file.txt");
reader = new BufferedReader(new FileReader(file));
I put file.txt in two place:
1) same folder of this SOURCE file.
2) in bin\...\ (same folder of this CLASS file)
But I allways receive NO FILE FOUND.
Please help me.
thanks :)
If the file ships with your application, it would be better accessed as a resource than as a file. Simply copy it to somewhere in your build path and use Class.getResourceAsStream or ClassLoader.getResourceAsStream. That way you'll also be able to access it if you bundle your app as a jar file.
Currently, you're looking for the file relative to the process's current working directory, which could be entirely unrelated to where the class files are.
if you put the file under sources and inside the package "test" for example, the path is:
./src/test/file.txt
you can use
File file = new File("./src/test/file.txt");
System.out.println(file.exists());
The path ./bin/test/file.txt will work in the second case and is more suitable for a normal java project