无法从src / main / resources文件夹Java 8中读取文件

Question

I have package as follows

src->main->java->com->Sample.java
src->main->resources->orders.csv

and

src->test->java->com->SampleTest.java
src->test->resources->orders.csv 

In Sample.java and SampleTest.java I have the following code

String file1 = "orders.csv";
Stream<String> lines1 = Files.lines(Paths.get(file1)); // Line 1

But i don't think code on Line 1 and Line 2 work. It does not find the file. Am i setting file1 and file2 correct?

Answer 1

Because these are resource files, you want to use Class#getResource(String) to search for the file relative to your class and get its absolute URL.

Your Sample.java will look like this:

String file1 = "/main/resources/orders.csv";
Stream<String> lines1 = Files.lines(Paths.get(Sample.class.getResource(file1).toURI()));

And your SampleTest.java will look like this:

String file1 = "/test/resources/orders.csv";
Stream<String> lines1 = Files.lines(Paths.get(Sample.class.getResource(file1).toURI()));

Now let my explain the syntax of the string " file1 ". If you look at the JavaDoc , you'll see that it says:

If the name begins with a '/' ('\/'), then the absolute name of the resource is the portion of the name following the '/'.

This basically means that the path provided, if it begins with a forward slash, is to be processed relative to your source directory. In other words, everything after the first forwards slash is a "subpath" of your source path. If there was no forward slash, the JVM would search for a package called "main" in the package defined by the current class loader. So "/main/resources/orders.csv" will be processed as "src/main/resources/orders.csv" , and "/test/resources/orders.csv" as "src/test/resources/orders.csv" .