Path.java
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上传日期:2018-01-08
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文件大小:9k
- /**
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements. See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership. The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License. You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- package org.apache.hadoop.fs;
- import java.net.*;
- import java.io.*;
- import org.apache.hadoop.conf.Configuration;
- /** Names a file or directory in a {@link FileSystem}.
- * Path strings use slash as the directory separator. A path string is
- * absolute if it begins with a slash.
- */
- public class Path implements Comparable {
- /** The directory separator, a slash. */
- public static final String SEPARATOR = "/";
- public static final char SEPARATOR_CHAR = '/';
-
- public static final String CUR_DIR = ".";
-
- static final boolean WINDOWS
- = System.getProperty("os.name").startsWith("Windows");
- private URI uri; // a hierarchical uri
- /** Resolve a child path against a parent path. */
- public Path(String parent, String child) {
- this(new Path(parent), new Path(child));
- }
- /** Resolve a child path against a parent path. */
- public Path(Path parent, String child) {
- this(parent, new Path(child));
- }
- /** Resolve a child path against a parent path. */
- public Path(String parent, Path child) {
- this(new Path(parent), child);
- }
- /** Resolve a child path against a parent 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;
- String parentPath = parentUri.getPath();
- if (!(parentPath.equals("/") || parentPath.equals("")))
- try {
- parentUri = new URI(parentUri.getScheme(), parentUri.getAuthority(),
- parentUri.getPath()+"/", null, null);
- } catch (URISyntaxException e) {
- throw new IllegalArgumentException(e);
- }
- URI resolved = parentUri.resolve(child.uri);
- initialize(resolved.getScheme(), resolved.getAuthority(),
- normalizePath(resolved.getPath()));
- }
- private void checkPathArg( String path ) {
- // disallow construction of a Path from an empty string
- if ( path == null ) {
- throw new IllegalArgumentException(
- "Can not create a Path from a null string");
- }
- if( path.length() == 0 ) {
- throw new IllegalArgumentException(
- "Can not create a Path from an empty string");
- }
- }
-
- /** Construct a path from a String. Path strings are URIs, but with
- * unescaped elements and some additional normalization. */
- public Path(String pathString) {
- checkPathArg( pathString );
-
- // We can't use 'new URI(String)' directly, since it assumes things are
- // escaped, which we don't require of Paths.
-
- // add a slash in front of paths with Windows drive letters
- if (hasWindowsDrive(pathString, false))
- pathString = "/"+pathString;
- // parse uri components
- String scheme = null;
- String authority = null;
- int start = 0;
- // parse uri scheme, if any
- int colon = pathString.indexOf(':');
- int slash = pathString.indexOf('/');
- if ((colon != -1) &&
- ((slash == -1) || (colon < slash))) { // has a scheme
- scheme = pathString.substring(0, colon);
- start = colon+1;
- }
- // parse uri authority, if any
- if (pathString.startsWith("//", start) &&
- (pathString.length()-start > 2)) { // has authority
- int nextSlash = pathString.indexOf('/', start+2);
- int authEnd = nextSlash > 0 ? nextSlash : pathString.length();
- authority = pathString.substring(start+2, authEnd);
- start = authEnd;
- }
- // uri path is the rest of the string -- query & fragment not supported
- String path = pathString.substring(start, pathString.length());
- initialize(scheme, authority, path);
- }
- /** Construct a Path from components. */
- public Path(String scheme, String authority, String path) {
- checkPathArg( path );
- initialize(scheme, authority, path);
- }
- private void initialize(String scheme, String authority, String path) {
- try {
- this.uri = new URI(scheme, authority, normalizePath(path), null, null)
- .normalize();
- } catch (URISyntaxException e) {
- throw new IllegalArgumentException(e);
- }
- }
- private String normalizePath(String path) {
- // remove double slashes & backslashes
- path = path.replace("//", "/");
- path = path.replace("\", "/");
-
- // trim trailing slash from non-root path (ignoring windows drive)
- int minLength = hasWindowsDrive(path, true) ? 4 : 1;
- if (path.length() > minLength && path.endsWith("/")) {
- path = path.substring(0, path.length()-1);
- }
-
- return path;
- }
- private boolean hasWindowsDrive(String path, boolean slashed) {
- if (!WINDOWS) return false;
- int start = slashed ? 1 : 0;
- return
- path.length() >= start+2 &&
- (slashed ? path.charAt(0) == '/' : true) &&
- path.charAt(start+1) == ':' &&
- ((path.charAt(start) >= 'A' && path.charAt(start) <= 'Z') ||
- (path.charAt(start) >= 'a' && path.charAt(start) <= 'z'));
- }
- /** Convert this to a URI. */
- public URI toUri() { return uri; }
- /** Return the FileSystem that owns this Path. */
- public FileSystem getFileSystem(Configuration conf) throws IOException {
- return FileSystem.get(this.toUri(), conf);
- }
- /** True if the directory of this path is absolute. */
- public boolean isAbsolute() {
- int start = hasWindowsDrive(uri.getPath(), true) ? 3 : 0;
- return uri.getPath().startsWith(SEPARATOR, start);
- }
- /** Returns 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. */
- public Path getParent() {
- String path = uri.getPath();
- int lastSlash = path.lastIndexOf('/');
- int start = hasWindowsDrive(path, true) ? 3 : 0;
- if ((path.length() == start) || // empty path
- (lastSlash == start && path.length() == start+1)) { // at root
- return null;
- }
- String parent;
- if (lastSlash==-1) {
- parent = CUR_DIR;
- } else {
- int end = hasWindowsDrive(path, true) ? 3 : 0;
- parent = path.substring(0, lastSlash==end?end+1:lastSlash);
- }
- return new Path(uri.getScheme(), uri.getAuthority(), parent);
- }
- /** Adds a suffix to the final name in the path.*/
- public Path suffix(String suffix) {
- return new Path(getParent(), getName()+suffix);
- }
- public String toString() {
- // we can't use uri.toString(), which escapes everything, because we want
- // illegal characters unescaped in the string, for glob processing, etc.
- StringBuffer buffer = new StringBuffer();
- if (uri.getScheme() != null) {
- buffer.append(uri.getScheme());
- buffer.append(":");
- }
- if (uri.getAuthority() != null) {
- buffer.append("//");
- buffer.append(uri.getAuthority());
- }
- if (uri.getPath() != null) {
- String path = uri.getPath();
- if (path.indexOf('/')==0 &&
- hasWindowsDrive(path, true) && // has windows drive
- uri.getScheme() == null && // but no scheme
- uri.getAuthority() == null) // or authority
- path = path.substring(1); // remove slash before drive
- buffer.append(path);
- }
- return buffer.toString();
- }
- public boolean equals(Object o) {
- if (!(o instanceof Path)) {
- return false;
- }
- Path that = (Path)o;
- return this.uri.equals(that.uri);
- }
- public int hashCode() {
- return uri.hashCode();
- }
- public int compareTo(Object o) {
- Path that = (Path)o;
- return this.uri.compareTo(that.uri);
- }
-
- /** Return the number of elements in this path. */
- public int depth() {
- String path = uri.getPath();
- int depth = 0;
- int slash = path.length()==1 && path.charAt(0)=='/' ? -1 : 0;
- while (slash != -1) {
- depth++;
- slash = path.indexOf(SEPARATOR, slash+1);
- }
- return depth;
- }
- /** Returns a qualified path object. */
- public Path makeQualified(FileSystem fs) {
- Path path = this;
- if (!isAbsolute()) {
- path = new Path(fs.getWorkingDirectory(), this);
- }
- URI pathUri = path.toUri();
- URI fsUri = fs.getUri();
-
- String scheme = pathUri.getScheme();
- String authority = pathUri.getAuthority();
- if (scheme != null &&
- (authority != null || fsUri.getAuthority() == null))
- return path;
- if (scheme == null) {
- scheme = fsUri.getScheme();
- }
- if (authority == null) {
- authority = fsUri.getAuthority();
- if (authority == null) {
- authority = "";
- }
- }
- return new Path(scheme+":"+"//"+authority + pathUri.getPath());
- }
- }