Spring Boot load another file from app.properties

Question

I am new to Spring Boot. I have this emailprop.properties in src/main/resource:

       //your private key  
       mail.smtp.dkim.privatekey=classpath:/emailproperties/private.key.der

But I am getting the error as

classpath:\email properties\private.key.der (The filename, directory name, or volume label syntax is incorrect)

How do I properly load this file?

Update-1

• my java code is dkimSigner = new DKIMSigner(emailProps.getProperty("mail.smtp.dkim.signingdomain"), emailProps.getProperty("mail.smtp.dkim.selector"), emailProps.getProperty("mail.smtp.dkim.privatekey"));

• its working as "D:\\WorkShop\\MyDemoProj\\EmailService\\src\\main\\resources\\private.key.der"Instead of emailProps.getProperty("mail.smtp.dkim.privatekey")

Update-2

• i have tried java code is String data = ""; ClassPathResource cpr = new ClassPathResource("private.key.der"); try { byte[] bdata = FileCopyUtils.copyToByteArray(cpr.getInputStream()); data = new String(bdata, StandardCharsets.UTF_8); } catch (IOException e) { e.printStackTrace(); } dkimSigner = new DKIMSigner(emailProps.getProperty("mail.smtp.dkim.signingdomain"), emailProps.getProperty("mail.smtp.dkim.selector"),data);

• Error is : java.io.FileNotFoundException: class path resource [classpath:private.key.der] cannot be resolved to URL because it does not exist

• Tried Code is : ClassPathResource resource = new ClassPathResource(emailProps.getProperty("mail.smtp.dkim.privatekey")); File file = resource.getFile(); String absolutePath = file.getAbsolutePath();

• Still same error..

• please update the answer..

Answer 1

If you want to load this file runtime then you need to use ResourceLoader please have a look here for the documentation - section 8.4.

Resource resource = resourceLoader.getResource("classpath:/emailproperties/private.key.der");

Now if you want to keep this exact path in properties file you can keep it there and then load it in your Autowired constructor/field like that:

@Value("${mail.smtp.dkim.privatekey}") String pathToPrivateKey

and then pass this to the resource loader.

Full example you can find here. I don't want to copy paste it.

Answer 2

If your file is located here:

"D:\\WorkShop\\MyDemoProj\\EmailService\\src\\main\\resources\\private.key.der" 

then it should be:

mail.smtp.dkim.privatekey=classpath:private.key.der

EDIT: I see now, you are using DKIMSigner, which expects file-path string,

Try changing your code like this:

ClassPathResource resource = new ClassPathResource(emailProps.getProperty("mail.smtp.dkim.privatekey"));
File file = resource.getFile();
String absolutePath = file.getAbsolutePath();
dkimSigner = new DKIMSigner(emailProps.getProperty("mail.smtp.dkim.signingdomain"), emailProps.getProperty("mail.smtp.dkim.selector"),absolutePath
);