How to copy a resource to a file in another location in Java

Question

I'm trying to copy a resource in my project onto another location on the disk. So far, I have this code:

if (!file.exists()){
    try {
        file.createNewFile();
        Files.copy(new InputSupplier<InputStream>() {
            public InputStream getInput() throws IOException {
                return Main.class.getResourceAsStream("/" + name);
            }
        }, file);                   
    } catch (IOException e) {
        file = null;
        return null;
    }
}

And it works fine, but the InputSupplier class is deprecated, so I was wondering if there was a better way to do what I'm trying to do.

Answer 1

See the documentation for the Guava InputSupplier class :

For InputSupplier<? extends InputStream> InputSupplier<? extends InputStream> , use ByteSource instead. For InputSupplier<? extends Reader> InputSupplier<? extends Reader> , use CharSource . Implementations of InputSupplier that don't fall into one of those categories do not benefit from any of the methods in common.io and should use a different interface. This interface is scheduled for removal in December 2015.

So in your case, you're looking for ByteSource :

Resources.asByteSource(url).copyTo(Files.asByteSink(file));

See this section of the Guava Wiki for more information.

---

If you're looking for a pure Java (no external libraries) version, you can do the following:

try (InputStream is = this.getClass().getClassLoader().getResourceAsStream("/" + name)) {
    Files.copy(is, Paths.get("C:\\some\\file.txt"));
} catch (IOException e) {
    // An error occurred copying the resource
}

Note that this is only valid for Java 7 and higher.