问题
I'm trying to read a file in my maven project at /src/main/resources/file.txt.
I'm using
URL url=this.getClass().getResource("/");
String filePath=url.getPath()+"file.txt";
url object gets the correct value when this is run thru eclipse.
But, when I package the jar and run it in command line:
jar -cp myjar.jar SampleTest
It returns null for 'url' object and throws a NullPointerException in the next line.
I have openend my Jar file using file browser and checked. It has the 'file.txt' in "/" location inside the Jar.
Where am I going wrong ?
回答1:
There are (often) no directories inside jar files. Therefor it will return null.
If you want to get the file you could get that resource directly:
URL fileUrl = getClass().getResource("/file.txt");
...
Or simply:
InputStream fileInputStream = getClass().getResourceAsStream("/file.txt");
回答2:
You should move that file into your CLASSPATH and get it like this:
InputStream is = this.getClass().getResourceAsStream("file.txt");
来源：https://stackoverflow.com/questions/11116020/getclass-getresource-returns-null-in-command-line