JarCastingpaths
Serializable wrapper for java.nio.file.Path
Filesystem-path convenience methods and bug-fixes:
import hammerlab.path._
val path = Path("") // current directory; URIs and Strings accepted
path.exists // true
path / 'src list // list children of src dir: Iterator(src/main,src/test)
Examples
Existence / Child-resolution
val src = path / 'src // "src" subdir
src.exists // true
path / 'foo exists // false
Directory-traversal
(path / 'src / 'test walk) filter (_.isFile)
// Iterator(
// src/test/resources/log4j.properties,
// src/test/resources/META-INF/services/java.nio.file.spi.FileSystemProvider,
// src/test/scala/org/hammerlab/paths/PathTest.scala
// )
IO
Self-explanatory methods:
def inputStream: InputStreamdef outputStream: OutputStreamdef read: Stringdef readBytes: Array[Byte]def write(String)def writeLines(Iterable[String])def lines: Iterator[String]def size: Long
Serializability
Paths are Serializable, delegating to the SerializablePath proxy, which serializes them as URIs.
JSR203 FileSystemProvider improvements
Interacting with Java NIO FileSystemProviders from Scala is broken; see scala/bug#10247.
Paths from this repo have hooks to lazily initialize and tweak the FileSystemProvider initialization code to resolve these problems; see FileSystems.scala.
There is also fix for a missing newByteChannel implementation in the JRE's default implementation of JarFileSystemProvider; use of Paths replaces it with a custom JarFileSystemProvider with this issue resolved.
As an example, try downloading the Google Cloud Storage NIO connector JAR, and querying for the existence and size of a public file:
wget -O lib/gcs-nio.jar http://search.maven.org/remotecontent?filepath=com/google/cloud/google-cloud-nio/0.28.0-alpha/google-cloud-nio-0.28.0-alpha-shaded.jar
sbt console
import hammerlab.path._
val index = Path("gs://gcp-public-data-landsat/index.csv.gz")
index.exists // true
index.size // 476118237
In contrast, trying the equivalent using vanilla Java NIO paths fails:
import java._, nio.file._, net._
val uri = new URI("gs://gcp-public-data-landsat/index.csv.gz")
Paths.get(uri)
// java.nio.file.FileSystemNotFoundException: Provider "gs" not installed
// at java.nio.file.Paths.get(Paths.java:147)
// ... 42 elided
(test this in a fresh sbt console, as initializing a hammerlab Path fixes the providers in that JVM)
