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HADOOP-13296. Cleanup javadoc for Path. Contributed by Daniel Templeton. 

(cherry picked from commit e15cd43369)
(cherry picked from commit 65b4f2682e)
This commit is contained in:
Akira Ajisaka 2016-06-21 20:16:22 +09:00
parent aa8f4cc48c
commit 6fefb8f4a4
1 changed files with 142 additions and 39 deletions
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181
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/Path.java
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@ -30,7 +30,8 @@
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
/** Names a file or directory in a {@link FileSystem}.
/**
* Names a file or directory in a {@link FileSystem}.
* Path strings use slash as the directory separator.
*/
@Stringable
@ -38,26 +39,37 @@
@InterfaceStability.Stable
public class Path implements Comparable {
/** The directory separator, a slash. */
/**
* The directory separator, a slash.
*/
public static final String SEPARATOR = "/";
/**
* The directory separator, a slash, as a character.
*/
public static final char SEPARATOR_CHAR = '/';
/**
* The current directory, ".".
*/
public static final String CUR_DIR = ".";
public static final boolean WINDOWS
= System.getProperty("os.name").startsWith("Windows");
/**
* Whether the current host is a Windows machine.
*/
public static final boolean WINDOWS =
System.getProperty("os.name").startsWith("Windows");
/**
* Pre-compiled regular expressions to detect path formats.
*/
private static final Pattern hasUriScheme =
Pattern.compile("^[a-zA-Z][a-zA-Z0-9+-.]+:");
private static final Pattern hasDriveLetterSpecifier =
private static final Pattern HAS_DRIVE_LETTER_SPECIFIER =
Pattern.compile("^/?[a-zA-Z]:");
private URI uri; // a hierarchical uri
private URI uri; // a hierarchical uri
/**
* Test whether this Path uses a scheme and is relative.
* Pathnames with scheme and relative path are illegal.
*/
void checkNotSchemeWithRelative() {
@ -73,6 +85,12 @@ void checkNotRelative() {
}
}
/**
* Return a version of the given Path without the scheme information.
*
* @param path the source Path
* @return a copy of this Path without the scheme information
*/
public static Path getPathWithoutSchemeAndAuthority(Path path) {
// This code depends on Path.toString() to remove the leading slash before
// the drive specification on Windows.
@ -82,22 +100,42 @@ public static Path getPathWithoutSchemeAndAuthority(Path path) {
return newPath;
}
/** Resolve a child path against a parent path. */
/**
* Create a new Path based on the child path resolved against the parent path.
*
* @param parent the parent path
* @param child the child path
*/
public Path(String parent, String child) {
this(new Path(parent), new Path(child));
}
/** Resolve a child path against a parent path. */
/**
* Create a new Path based on the child path resolved against the parent path.
*
* @param parent the parent path
* @param child the child path
*/
public Path(Path parent, String child) {
this(parent, new Path(child));
}
/** Resolve a child path against a parent path. */
/**
* Create a new Path based on the child path resolved against the parent path.
*
* @param parent the parent path
* @param child the child path
*/
public Path(String parent, Path child) {
this(new Path(parent), child);
}
/** Resolve a child path against a parent path. */
/**
* Create a new Path based on the child path resolved against the parent path.
*
* @param parent the parent path
* @param child the child path
*/
public Path(Path parent, Path child) {
// Add a slash to parent's path so resolution is compatible with URI's
URI parentUri = parent.uri;
@ -127,8 +165,12 @@ private void checkPathArg( String path ) throws IllegalArgumentException {
}
}
/** Construct a path from a String. Path strings are URIs, but with
* unescaped elements and some additional normalization. */
/**
* Construct a path from a String. Path strings are URIs, but with
* unescaped elements and some additional normalization.
*
* @param pathString the path string
*/
public Path(String pathString) throws IllegalArgumentException {
checkPathArg( pathString );
@ -172,12 +214,20 @@ public Path(String pathString) throws IllegalArgumentException {
/**
* Construct a path from a URI
*
* @param aUri the source URI
*/
public Path(URI aUri) {
uri = aUri.normalize();
}
/** Construct a Path from components. */
/**
* Construct a Path from components.
*
* @param scheme the scheme
* @param authority the authority
* @param path the path
*/
public Path(String scheme, String authority, String path) {
checkPathArg( path );
@ -210,9 +260,9 @@ private void initialize(String scheme, String authority, String path,
* The returned path has the scheme and authority of the first path. On
* Windows, the drive specification in the second path is discarded.
*
* @param path1 Path first path
* @param path2 Path second path, to be appended relative to path1
* @return Path merged path
* @param path1 the first path
* @param path2 the second path, to be appended relative to path1
* @return the merged path
*/
public static Path mergePaths(Path path1, Path path2) {
String path2Str = path2.toUri().getPath();
@ -228,10 +278,11 @@ public static Path mergePaths(Path path1, Path path2) {
/**
* Normalize a path string to use non-duplicated forward slashes as
* the path separator and remove any trailing path separators.
* @param scheme Supplies the URI scheme. Used to deduce whether we
* should replace backslashes or not.
* @param path Supplies the scheme-specific part
* @return Normalized path string.
*
* @param scheme the URI scheme. Used to deduce whether we
* should replace backslashes or not
* @param path the scheme-specific part
* @return the normalized path string
*/
private static String normalizePath(String scheme, String path) {
// Remove double forward slashes.
@ -257,7 +308,7 @@ private static String normalizePath(String scheme, String path) {
}
private static boolean hasWindowsDrive(String path) {
return (WINDOWS && hasDriveLetterSpecifier.matcher(path).find());
return (WINDOWS && HAS_DRIVE_LETTER_SPECIFIER.matcher(path).find());
}
private static int startPositionWithoutWindowsDrive(String path) {
@ -272,10 +323,10 @@ private static int startPositionWithoutWindowsDrive(String path) {
* Determine whether a given path string represents an absolute path on
* Windows. e.g. "C:/a/b" is an absolute path. "C:a/b" is not.
*
* @param pathString Supplies the path string to evaluate.
* @param slashed true if the given path is prefixed with "/".
* @param pathString the path string to evaluate
* @param slashed true if the given path is prefixed with "/"
* @return true if the supplied path looks like an absolute path with a Windows
* drive-specifier.
* drive-specifier
*/
public static boolean isWindowsAbsolutePath(final String pathString,
final boolean slashed) {
@ -286,17 +337,32 @@ public static boolean isWindowsAbsolutePath(final String pathString,
(pathString.charAt(start) == '\\'));
}
/** Convert this to a URI. */
/**
* Convert this Path to a URI.
*
* @return this Path as a URI
*/
public URI toUri() { return uri; }
/** Return the FileSystem that owns this Path. */
/**
* Return the FileSystem that owns this Path.
*
* @param conf the configuration to use when resolving the FileSystem
* @return the FileSystem that owns this Path
* @throws java.io.IOException thrown if there's an issue resolving the
* FileSystem
*/
public FileSystem getFileSystem(Configuration conf) throws IOException {
return FileSystem.get(this.toUri(), conf);
}
/**
* Is an absolute path (ie a slash relative path part)
* AND a scheme is null AND authority is null.
* Returns true if the path component (i.e. directory) of this URI is
* absolute <strong>and</strong> the scheme is null, <b>and</b> the authority
* is null.
*
* @return whether the path is absolute and the URI has no scheme nor
* authority parts
*/
public boolean isAbsoluteAndSchemeAuthorityNull() {
return (isUriPathAbsolute() &&
@ -304,33 +370,50 @@ public boolean isAbsoluteAndSchemeAuthorityNull() {
}
/**
* True if the path component (i.e. directory) of this URI is absolute.
* Returns true if the path component (i.e. directory) of this URI is
* absolute.
*
* @return whether this URI's path is absolute
*/
public boolean isUriPathAbsolute() {
int start = startPositionWithoutWindowsDrive(uri.getPath());
return uri.getPath().startsWith(SEPARATOR, start);
}
/** True if the path is not a relative path and starts with root. */
/**
* Returns true if the path component (i.e. directory) of this URI is
* absolute. This method is a wrapper for {@link #isUriPathAbsolute()}.
*
* @return whether this URI's path is absolute
*/
public boolean isAbsolute() {
return isUriPathAbsolute();
}
/**
* Returns true if and only if this path represents the root of a file system.
*
* @return true if and only if this path represents the root of a file system
*/
public boolean isRoot() {
return getParent() == null;
}
/** Returns the final component of this path.*/
/**
* Returns the final component of this path.
*
* @return the final component of this path
*/
public String getName() {
String path = uri.getPath();
int slash = path.lastIndexOf(SEPARATOR);
return path.substring(slash+1);
}
/** Returns the parent of a path or null if at root. */
/**
* Returns the parent of a path or null if at root.
* @return the parent of a path or null if at root
*/
public Path getParent() {
String path = uri.getPath();
int lastSlash = path.lastIndexOf('/');
@ -348,7 +431,12 @@ public Path getParent() {
return new Path(uri.getScheme(), uri.getAuthority(), parent);
}
/** Adds a suffix to the final name in the path.*/
/**
* Adds a suffix to the final name in the path.
*
* @param suffix the suffix to add
* @return a new path with the suffix added
*/
public Path suffix(String suffix) {
return new Path(getParent(), getName()+suffix);
}
@ -402,7 +490,10 @@ public int compareTo(Object o) {
return this.uri.compareTo(that.uri);
}
/** Return the number of elements in this path. */
/**
* Returns the number of elements in this path.
* @return the number of elements in this path
*/
public int depth() {
String path = uri.getPath();
int depth = 0;
@ -415,16 +506,28 @@ public int depth() {
}
/**
* Returns a qualified path object.
* Returns a qualified path object for the {@link FileSystem}'s working
* directory.
*
* Deprecated - use {@link #makeQualified(URI, Path)}
* @param fs the target FileSystem
* @return a qualified path object for the FileSystem's working directory
* @deprecated use {@link #makeQualified(URI, Path)}
*/
@Deprecated
public Path makeQualified(FileSystem fs) {
return makeQualified(fs.getUri(), fs.getWorkingDirectory());
}
/** Returns a qualified path object. */
/**
* Returns a qualified path object.
*
* @param defaultUri if this path is missing the scheme or authority
* components, borrow them from this URI
* @param workingDir if this path isn't absolute, treat it as relative to this
* working directory
* @return this path if it contains a scheme and authority and is absolute, or
* a new path that includes a path and authority and is fully qualified
*/
@InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"})
public Path makeQualified(URI defaultUri, Path workingDir ) {
Path path = this;