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Paths.java
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/*
* Copyright (c) 2007, 2011, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
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package java.nio.file;
import java.nio.file.spi.FileSystemProvider;
import java.net.URI;
/**
* This class consists exclusively of static methods that return a {@link Path}
* by converting a path string or {@link URI}.
*
* @since 1.7
*/
public final class Paths {
private Paths() { }
/**
* Converts a path string, or a sequence of strings that when joined form
* a path string, to a {@code Path}. If {@code more} does not specify any
* elements then the value of the {@code first} parameter is the path string
* to convert. If {@code more} specifies one or more elements then each
* non-empty string, including {@code first}, is considered to be a sequence
* of name elements (see {@link Path}) and is joined to form a path string.
* The details as to how the Strings are joined is provider specific but
* typically they will be joined using the {@link FileSystem#getSeparator
* name-separator} as the separator. For example, if the name separator is
* "{@code /}" and {@code getPath("/foo","bar","gus")} is invoked, then the
* path string {@code "/foo/bar/gus"} is converted to a {@code Path}.
* A {@code Path} representing an empty path is returned if {@code first}
* is the empty string and {@code more} does not contain any non-empty
* strings.
*
* <p> The {@code Path} is obtained by invoking the {@link FileSystem#getPath
* getPath} method of the {@link FileSystems#getDefault default} {@link
* FileSystem}.
*
* <p> Note that while this method is very convenient, using it will imply
* an assumed reference to the default {@code FileSystem} and limit the
* utility of the calling code. Hence it should not be used in library code
* intended for flexible reuse. A more flexible alternative is to use an
* existing {@code Path} instance as an anchor, such as:
* <pre>
* Path dir = ...
* Path path = dir.resolve("file");
* </pre>
*
* @param first
* the path string or initial part of the path string
* @param more
* additional strings to be joined to form the path string
*
* @return the resulting {@code Path}
*
* @throws InvalidPathException
* if the path string cannot be converted to a {@code Path}
*
* @see FileSystem#getPath
*/
public static Path get(String first, String... more) {
return FileSystems.getDefault().getPath(first, more);
}
/**
* Converts the given URI to a {@link Path} object.
*
* <p> This method iterates over the {@link FileSystemProvider#installedProviders()
* installed} providers to locate the provider that is identified by the
* URI {@link URI#getScheme scheme} of the given URI. URI schemes are
* compared without regard to case. If the provider is found then its {@link
* FileSystemProvider#getPath getPath} method is invoked to convert the
* URI.
*
* <p> In the case of the default provider, identified by the URI scheme
* "file", the given URI has a non-empty path component, and undefined query
* and fragment components. Whether the authority component may be present
* is platform specific. The returned {@code Path} is associated with the
* {@link FileSystems#getDefault default} file system.
*
* <p> The default provider provides a similar <em>round-trip</em> guarantee
* to the {@link java.io.File} class. For a given {@code Path} <i>p</i> it
* is guaranteed that
* <blockquote><tt>
* Paths.get(</tt><i>p</i><tt>.{@link Path#toUri() toUri}()).equals(</tt>
* <i>p</i><tt>.{@link Path#toAbsolutePath() toAbsolutePath}())</tt>
* </blockquote>
* so long as the original {@code Path}, the {@code URI}, and the new {@code
* Path} are all created in (possibly different invocations of) the same
* Java virtual machine. Whether other providers make any guarantees is
* provider specific and therefore unspecified.
*
* @param uri
* the URI to convert
*
* @return the resulting {@code Path}
*
* @throws IllegalArgumentException
* if preconditions on the {@code uri} parameter do not hold. The
* format of the URI is provider specific.
* @throws FileSystemNotFoundException
* The file system, identified by the URI, does not exist and
* cannot be created automatically, or the provider identified by
* the URI's scheme component is not installed
* @throws SecurityException
* if a security manager is installed and it denies an unspecified
* permission to access the file system
*/
public static Path get(URI uri) {
String scheme = uri.getScheme();
if (scheme == null)
throw new IllegalArgumentException("Missing scheme");
// check for default provider to avoid loading of installed providers
if (scheme.equalsIgnoreCase("file"))
return FileSystems.getDefault().provider().getPath(uri);
// try to find provider
for (FileSystemProvider provider: FileSystemProvider.installedProviders()) {
if (provider.getScheme().equalsIgnoreCase(scheme)) {
return provider.getPath(uri);
}
}
throw new FileSystemNotFoundException("Provider \"" + scheme + "\" not installed");
}
}