PathTool.java
package org.codehaus.plexus.util;
/*
* Copyright The Codehaus Foundation.
*
* Licensed 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.
*/
import java.io.File;
import java.util.StringTokenizer;
/**
* Path tool contains static methods to assist in determining path-related information such as relative paths.
*
* @author <a href="mailto:pete-apache-dev@kazmier.com">Pete Kazmier</a>
* @author <a href="mailto:vmassol@apache.org">Vincent Massol</a>
* @author <a href="mailto:vincent.siveton@gmail.com">Vincent Siveton</a>
*
*/
public class PathTool {
/**
* <p>Determines the relative path of a filename from a base directory. This method is useful in building relative
* links within pages of a web site. It provides similar functionality to Anakia's <code>$relativePath</code>
* context variable. The arguments to this method may contain either forward or backward slashes as file separators.
* The relative path returned is formed using forward slashes as it is expected this path is to be used as a link in
* a web page (again mimicking Anakia's behavior).</p>
*
* <p>This method is thread-safe.</p>
*
* <pre>
* PathTool.getRelativePath( null, null ) = ""
* PathTool.getRelativePath( null, "/usr/local/java/bin" ) = ""
* PathTool.getRelativePath( "/usr/local/", null ) = ""
* PathTool.getRelativePath( "/usr/local/", "/usr/local/java/bin" ) = ".."
* PathTool.getRelativePath( "/usr/local/", "/usr/local/java/bin/java.sh" ) = "../.."
* PathTool.getRelativePath( "/usr/local/java/bin/java.sh", "/usr/local/" ) = ""
* </pre>
*
* @param basedir The base directory.
* @param filename The filename that is relative to the base directory.
* @return The relative path of the filename from the base directory. This value is not terminated with a forward
* slash. A zero-length string is returned if: the filename is not relative to the base directory,
* <code>basedir</code> is null or zero-length, or <code>filename</code> is null or zero-length.
*/
public static final String getRelativePath(String basedir, String filename) {
basedir = uppercaseDrive(basedir);
filename = uppercaseDrive(filename);
/*
* Verify the arguments and make sure the filename is relative to the base directory.
*/
if (basedir == null
|| basedir.length() == 0
|| filename == null
|| filename.length() == 0
|| !filename.startsWith(basedir)) {
return "";
}
/*
* Normalize the arguments. First, determine the file separator that is being used, then strip that off the end
* of both the base directory and filename.
*/
String separator = determineSeparator(filename);
basedir = StringUtils.chompLast(basedir, separator);
filename = StringUtils.chompLast(filename, separator);
/*
* Remove the base directory from the filename to end up with a relative filename (relative to the base
* directory). This filename is then used to determine the relative path.
*/
String relativeFilename = filename.substring(basedir.length());
return determineRelativePath(relativeFilename, separator);
}
/**
* <p>Determines the relative path of a filename. This method is useful in building relative links within pages of a
* web site. It provides similar functionality to Anakia's <code>$relativePath</code> context variable. The argument
* to this method may contain either forward or backward slashes as file separators. The relative path returned is
* formed using forward slashes as it is expected this path is to be used as a link in a web page (again mimicking
* Anakia's behavior).</p>
*
* <p>This method is thread-safe.</p>
*
* @param filename The filename to be parsed.
* @return The relative path of the filename. This value is not terminated with a forward slash. A zero-length
* string is returned if: <code>filename</code> is null or zero-length.
* @see #getRelativeFilePath(String, String)
*/
public static final String getRelativePath(String filename) {
filename = uppercaseDrive(filename);
if (filename == null || filename.length() == 0) {
return "";
}
/*
* Normalize the argument. First, determine the file separator that is being used, then strip that off the end
* of the filename. Then, if the filename doesn't begin with a separator, add one.
*/
String separator = determineSeparator(filename);
filename = StringUtils.chompLast(filename, separator);
if (!filename.startsWith(separator)) {
filename = separator + filename;
}
return determineRelativePath(filename, separator);
}
/**
* <p>Determines the directory component of a filename. This is useful within DVSL templates when used in conjunction
* with the DVSL's <code>$context.getAppValue("infilename")</code> to get the current directory that is currently
* being processed.</p>
*
* <p>This method is thread-safe.</p>
*
* <pre>
* PathTool.getDirectoryComponent( null ) = ""
* PathTool.getDirectoryComponent( "/usr/local/java/bin" ) = "/usr/local/java"
* PathTool.getDirectoryComponent( "/usr/local/java/bin/" ) = "/usr/local/java/bin"
* PathTool.getDirectoryComponent( "/usr/local/java/bin/java.sh" ) = "/usr/local/java/bin"
* </pre>
*
* @param filename The filename to be parsed.
* @return The directory portion of the <code>filename</code>. If the filename does not contain a directory
* component, "." is returned.
*/
public static final String getDirectoryComponent(String filename) {
if (filename == null || filename.length() == 0) {
return "";
}
String separator = determineSeparator(filename);
String directory = StringUtils.chomp(filename, separator);
if (filename.equals(directory)) {
return ".";
}
return directory;
}
/**
* Calculates the appropriate link given the preferred link and the relativePath of the document.
*
* <pre>
* PathTool.calculateLink( "/index.html", "../.." ) = "../../index.html"
* PathTool.calculateLink( "http://plexus.codehaus.org/plexus-utils/index.html", "../.." ) = "http://plexus.codehaus.org/plexus-utils/index.html"
* PathTool.calculateLink( "/usr/local/java/bin/java.sh", "../.." ) = "../../usr/local/java/bin/java.sh"
* PathTool.calculateLink( "../index.html", "/usr/local/java/bin" ) = "/usr/local/java/bin/../index.html"
* PathTool.calculateLink( "../index.html", "http://plexus.codehaus.org/plexus-utils" ) = "http://plexus.codehaus.org/plexus-utils/../index.html"
* </pre>
*
* @param link main link
* @param relativePath relative
* @return String
*/
public static final String calculateLink(String link, String relativePath) {
if (link == null) {
link = "";
}
if (relativePath == null) {
relativePath = "";
}
// This must be some historical feature
if (link.startsWith("/site/")) {
return link.substring(5);
}
// Allows absolute links in nav-bars etc
if (link.startsWith("/absolute/")) {
return link.substring(10);
}
// This traps urls like http://
if (link.contains(":")) {
return link;
}
// If relativepath is current directory, just pass the link through
if (StringUtils.equals(relativePath, ".")) {
if (link.startsWith("/")) {
return link.substring(1);
}
return link;
}
// If we don't do this, you can end up with ..//bob.html rather than ../bob.html
if (relativePath.endsWith("/") && link.startsWith("/")) {
return relativePath + "." + link.substring(1);
}
if (relativePath.endsWith("/") || link.startsWith("/")) {
return relativePath + link;
}
return relativePath + "/" + link;
}
/**
* This method can calculate the relative path between two paths on a web site.
*
* <pre>
* PathTool.getRelativeWebPath( null, null ) = ""
* PathTool.getRelativeWebPath( null, "http://plexus.codehaus.org/" ) = ""
* PathTool.getRelativeWebPath( "http://plexus.codehaus.org/", null ) = ""
* PathTool.getRelativeWebPath( "http://plexus.codehaus.org/",
* "http://plexus.codehaus.org/plexus-utils/index.html" ) = "plexus-utils/index.html"
* PathTool.getRelativeWebPath( "http://plexus.codehaus.org/plexus-utils/index.html",
* "http://plexus.codehaus.org/" = "../../"
* </pre>
*
* @param oldPath main path
* @param newPath second path
* @return a relative web path from <code>oldPath</code>.
*/
public static final String getRelativeWebPath(final String oldPath, final String newPath) {
if (StringUtils.isEmpty(oldPath) || StringUtils.isEmpty(newPath)) {
return "";
}
String resultPath = buildRelativePath(newPath, oldPath, '/');
if (newPath.endsWith("/") && !resultPath.endsWith("/")) {
return resultPath + "/";
}
return resultPath;
}
/**
* This method can calculate the relative path between two paths on a file system.
*
* <pre>
* PathTool.getRelativeFilePath( null, null ) = ""
* PathTool.getRelativeFilePath( null, "/usr/local/java/bin" ) = ""
* PathTool.getRelativeFilePath( "/usr/local", null ) = ""
* PathTool.getRelativeFilePath( "/usr/local", "/usr/local/java/bin" ) = "java/bin"
* PathTool.getRelativeFilePath( "/usr/local", "/usr/local/java/bin/" ) = "java/bin"
* PathTool.getRelativeFilePath( "/usr/local/java/bin", "/usr/local/" ) = "../.."
* PathTool.getRelativeFilePath( "/usr/local/", "/usr/local/java/bin/java.sh" ) = "java/bin/java.sh"
* PathTool.getRelativeFilePath( "/usr/local/java/bin/java.sh", "/usr/local/" ) = "../../.."
* PathTool.getRelativeFilePath( "/usr/local/", "/bin" ) = "../../bin"
* PathTool.getRelativeFilePath( "/bin", "/usr/local/" ) = "../usr/local"
* </pre>
*
* Note: On Windows based system, the <code>/</code> character should be replaced by <code>\</code> character.
*
* @param oldPath main path
* @param newPath second path
* @return a relative file path from <code>oldPath</code>.
*/
public static final String getRelativeFilePath(final String oldPath, final String newPath) {
if (StringUtils.isEmpty(oldPath) || StringUtils.isEmpty(newPath)) {
return "";
}
// normalise the path delimiters
String fromPath = new File(oldPath).getPath();
String toPath = new File(newPath).getPath();
// strip any leading slashes if its a windows path
if (toPath.matches("^\\[a-zA-Z]:")) {
toPath = toPath.substring(1);
}
if (fromPath.matches("^\\[a-zA-Z]:")) {
fromPath = fromPath.substring(1);
}
// lowercase windows drive letters.
if (fromPath.startsWith(":", 1)) {
fromPath = Character.toLowerCase(fromPath.charAt(0)) + fromPath.substring(1);
}
if (toPath.startsWith(":", 1)) {
toPath = Character.toLowerCase(toPath.charAt(0)) + toPath.substring(1);
}
// check for the presence of windows drives. No relative way of
// traversing from one to the other.
if ((toPath.startsWith(":", 1) && fromPath.startsWith(":", 1))
&& (!toPath.substring(0, 1).equals(fromPath.substring(0, 1)))) {
// they both have drive path element but they dont match, no
// relative path
return null;
}
if ((toPath.startsWith(":", 1) && !fromPath.startsWith(":", 1))
|| (!toPath.startsWith(":", 1) && fromPath.startsWith(":", 1))) {
// one has a drive path element and the other doesnt, no relative
// path.
return null;
}
String resultPath = buildRelativePath(toPath, fromPath, File.separatorChar);
if (newPath.endsWith(File.separator) && !resultPath.endsWith(File.separator)) {
return resultPath + File.separator;
}
return resultPath;
}
// ----------------------------------------------------------------------
// Private methods
// ----------------------------------------------------------------------
/**
* Determines the relative path of a filename. For each separator within the filename (except the leading if
* present), append the "../" string to the return value.
*
* @param filename The filename to parse.
* @param separator The separator used within the filename.
* @return The relative path of the filename. This value is not terminated with a forward slash. A zero-length
* string is returned if: the filename is zero-length.
*/
private static final String determineRelativePath(String filename, String separator) {
if (filename.length() == 0) {
return "";
}
/*
* Count the slashes in the relative filename, but exclude the leading slash. If the path has no slashes, then
* the filename is relative to the current directory.
*/
int slashCount = StringUtils.countMatches(filename, separator) - 1;
if (slashCount <= 0) {
return ".";
}
/*
* The relative filename contains one or more slashes indicating that the file is within one or more
* directories. Thus, each slash represents a "../" in the relative path.
*/
StringBuilder sb = new StringBuilder();
for (int i = 0; i < slashCount; i++) {
sb.append("../");
}
/*
* Finally, return the relative path but strip the trailing slash to mimic Anakia's behavior.
*/
return StringUtils.chop(sb.toString());
}
/**
* Helper method to determine the file separator (forward or backward slash) used in a filename. The slash that
* occurs more often is returned as the separator.
*
* @param filename The filename parsed to determine the file separator.
* @return The file separator used within <code>filename</code>. This value is either a forward or backward slash.
*/
private static final String determineSeparator(String filename) {
int forwardCount = StringUtils.countMatches(filename, "/");
int backwardCount = StringUtils.countMatches(filename, "\\");
return forwardCount >= backwardCount ? "/" : "\\";
}
/**
* Cygwin prefers lowercase drive letters, but other parts of maven use uppercase
*
* @param path
* @return String
*/
static final String uppercaseDrive(String path) {
if (path == null) {
return null;
}
if (path.length() >= 2 && path.charAt(1) == ':') {
path = Character.toUpperCase(path.charAt(0)) + path.substring(1);
}
return path;
}
private static final String buildRelativePath(String toPath, String fromPath, final char separatorChar) {
// use tokeniser to traverse paths and for lazy checking
StringTokenizer toTokeniser = new StringTokenizer(toPath, String.valueOf(separatorChar));
StringTokenizer fromTokeniser = new StringTokenizer(fromPath, String.valueOf(separatorChar));
int count = 0;
// walk along the to path looking for divergence from the from path
while (toTokeniser.hasMoreTokens() && fromTokeniser.hasMoreTokens()) {
if (separatorChar == '\\') {
if (!fromTokeniser.nextToken().equalsIgnoreCase(toTokeniser.nextToken())) {
break;
}
} else {
if (!fromTokeniser.nextToken().equals(toTokeniser.nextToken())) {
break;
}
}
count++;
}
// reinitialise the tokenisers to count positions to retrieve the
// gobbled token
toTokeniser = new StringTokenizer(toPath, String.valueOf(separatorChar));
fromTokeniser = new StringTokenizer(fromPath, String.valueOf(separatorChar));
while (count-- > 0) {
fromTokeniser.nextToken();
toTokeniser.nextToken();
}
String relativePath = "";
// add back refs for the rest of from location.
while (fromTokeniser.hasMoreTokens()) {
fromTokeniser.nextToken();
relativePath += "..";
if (fromTokeniser.hasMoreTokens()) {
relativePath += separatorChar;
}
}
if (relativePath.length() != 0 && toTokeniser.hasMoreTokens()) {
relativePath += separatorChar;
}
// add fwd fills for whatevers left of newPath.
while (toTokeniser.hasMoreTokens()) {
relativePath += toTokeniser.nextToken();
if (toTokeniser.hasMoreTokens()) {
relativePath += separatorChar;
}
}
return relativePath;
}
}