1/*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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8 * particular file as subject to the "Classpath" exception as provided
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10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
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24 */
25
26package java.nio.file;
27
28import java.nio.file.spi.FileSystemProvider;
29import java.net.URI;
30
31/**
32 * This class consists exclusively of static methods that return a {@link Path}
33 * by converting a path string or {@link URI}.
34 *
35 * @since 1.7
36 */
37
38public final class Paths {
39    private Paths() { }
40
41    /**
42     * Converts a path string, or a sequence of strings that when joined form
43     * a path string, to a {@code Path}. If {@code more} does not specify any
44     * elements then the value of the {@code first} parameter is the path string
45     * to convert. If {@code more} specifies one or more elements then each
46     * non-empty string, including {@code first}, is considered to be a sequence
47     * of name elements (see {@link Path}) and is joined to form a path string.
48     * The details as to how the Strings are joined is provider specific but
49     * typically they will be joined using the {@link FileSystem#getSeparator
50     * name-separator} as the separator. For example, if the name separator is
51     * "{@code /}" and {@code getPath("/foo","bar","gus")} is invoked, then the
52     * path string {@code "/foo/bar/gus"} is converted to a {@code Path}.
53     * A {@code Path} representing an empty path is returned if {@code first}
54     * is the empty string and {@code more} does not contain any non-empty
55     * strings.
56     *
57     * <p> The {@code Path} is obtained by invoking the {@link FileSystem#getPath
58     * getPath} method of the {@link FileSystems#getDefault default} {@link
59     * FileSystem}.
60     *
61     * <p> Note that while this method is very convenient, using it will imply
62     * an assumed reference to the default {@code FileSystem} and limit the
63     * utility of the calling code. Hence it should not be used in library code
64     * intended for flexible reuse. A more flexible alternative is to use an
65     * existing {@code Path} instance as an anchor, such as:
66     * <pre>
67     *     Path dir = ...
68     *     Path path = dir.resolve("file");
69     * </pre>
70     *
71     * @param   first
72     *          the path string or initial part of the path string
73     * @param   more
74     *          additional strings to be joined to form the path string
75     *
76     * @return  the resulting {@code Path}
77     *
78     * @throws  InvalidPathException
79     *          if the path string cannot be converted to a {@code Path}
80     *
81     * @see FileSystem#getPath
82     */
83    public static Path get(String first, String... more) {
84        return FileSystems.getDefault().getPath(first, more);
85    }
86
87    /**
88     * Converts the given URI to a {@link Path} object.
89     *
90     * <p> This method iterates over the {@link FileSystemProvider#installedProviders()
91     * installed} providers to locate the provider that is identified by the
92     * URI {@link URI#getScheme scheme} of the given URI. URI schemes are
93     * compared without regard to case. If the provider is found then its {@link
94     * FileSystemProvider#getPath getPath} method is invoked to convert the
95     * URI.
96     *
97     * <p> In the case of the default provider, identified by the URI scheme
98     * "file", the given URI has a non-empty path component, and undefined query
99     * and fragment components. Whether the authority component may be present
100     * is platform specific. The returned {@code Path} is associated with the
101     * {@link FileSystems#getDefault default} file system.
102     *
103     * <p> The default provider provides a similar <em>round-trip</em> guarantee
104     * to the {@link java.io.File} class. For a given {@code Path} <i>p</i> it
105     * is guaranteed that
106     * <blockquote>{@code
107     * Paths.get(}<i>p</i>{@code .}{@link Path#toUri() toUri}{@code ()).equals(}
108     * <i>p</i>{@code .}{@link Path#toAbsolutePath() toAbsolutePath}{@code ())}
109     * </blockquote>
110     * so long as the original {@code Path}, the {@code URI}, and the new {@code
111     * Path} are all created in (possibly different invocations of) the same
112     * Java virtual machine. Whether other providers make any guarantees is
113     * provider specific and therefore unspecified.
114     *
115     * @param   uri
116     *          the URI to convert
117     *
118     * @return  the resulting {@code Path}
119     *
120     * @throws  IllegalArgumentException
121     *          if preconditions on the {@code uri} parameter do not hold. The
122     *          format of the URI is provider specific.
123     * @throws  FileSystemNotFoundException
124     *          The file system, identified by the URI, does not exist and
125     *          cannot be created automatically, or the provider identified by
126     *          the URI's scheme component is not installed
127     * @throws  SecurityException
128     *          if a security manager is installed and it denies an unspecified
129     *          permission to access the file system
130     */
131    public static Path get(URI uri) {
132        String scheme =  uri.getScheme();
133        if (scheme == null)
134            throw new IllegalArgumentException("Missing scheme");
135
136        // check for default provider to avoid loading of installed providers
137        if (scheme.equalsIgnoreCase("file"))
138            return FileSystems.getDefault().provider().getPath(uri);
139
140        // try to find provider
141        for (FileSystemProvider provider: FileSystemProvider.installedProviders()) {
142            if (provider.getScheme().equalsIgnoreCase(scheme)) {
143                return provider.getPath(uri);
144            }
145        }
146
147        throw new FileSystemNotFoundException("Provider \"" + scheme + "\" not installed");
148    }
149}
150