给出两条绝对路径,例如
/var/data/stuff/xyz.dat
/var/data
如何创建一个以第二条路径为基础的相对路径?在上面的例子中,结果应该是:./stuff/xyz.dat
给出两条绝对路径,例如
/var/data/stuff/xyz.dat
/var/data
如何创建一个以第二条路径为基础的相对路径?在上面的例子中,结果应该是:./stuff/xyz.dat
当前回答
我的版本大致基于马特和史蒂夫的版本:
/**
* Returns the path of one File relative to another.
*
* @param target the target directory
* @param base the base directory
* @return target's path relative to the base directory
* @throws IOException if an error occurs while resolving the files' canonical names
*/
public static File getRelativeFile(File target, File base) throws IOException
{
String[] baseComponents = base.getCanonicalPath().split(Pattern.quote(File.separator));
String[] targetComponents = target.getCanonicalPath().split(Pattern.quote(File.separator));
// skip common components
int index = 0;
for (; index < targetComponents.length && index < baseComponents.length; ++index)
{
if (!targetComponents[index].equals(baseComponents[index]))
break;
}
StringBuilder result = new StringBuilder();
if (index != baseComponents.length)
{
// backtrack to base directory
for (int i = index; i < baseComponents.length; ++i)
result.append(".." + File.separator);
}
for (; index < targetComponents.length; ++index)
result.append(targetComponents[index] + File.separator);
if (!target.getPath().endsWith("/") && !target.getPath().endsWith("\\"))
{
// remove final path separator
result.delete(result.length() - File.separator.length(), result.length());
}
return new File(result.toString());
}
其他回答
我的版本大致基于马特和史蒂夫的版本:
/**
* Returns the path of one File relative to another.
*
* @param target the target directory
* @param base the base directory
* @return target's path relative to the base directory
* @throws IOException if an error occurs while resolving the files' canonical names
*/
public static File getRelativeFile(File target, File base) throws IOException
{
String[] baseComponents = base.getCanonicalPath().split(Pattern.quote(File.separator));
String[] targetComponents = target.getCanonicalPath().split(Pattern.quote(File.separator));
// skip common components
int index = 0;
for (; index < targetComponents.length && index < baseComponents.length; ++index)
{
if (!targetComponents[index].equals(baseComponents[index]))
break;
}
StringBuilder result = new StringBuilder();
if (index != baseComponents.length)
{
// backtrack to base directory
for (int i = index; i < baseComponents.length; ++i)
result.append(".." + File.separator);
}
for (; index < targetComponents.length; ++index)
result.append(targetComponents[index] + File.separator);
if (!target.getPath().endsWith("/") && !target.getPath().endsWith("\\"))
{
// remove final path separator
result.delete(result.length() - File.separator.length(), result.length());
}
return new File(result.toString());
}
当使用java.net.URI.relativize时,你应该注意Java错误: JDK-6226081 (URI应该能够将路径与部分根相对化)
目前,URI的relativize()方法只在一个URI是另一个URI的前缀时才会相对化URI。
这本质上意味着java.net.URI.relativize将不会创建“…这是给你的。
如果你正在编写一个Maven插件,你可以使用Plexus的PathTool:
import org.codehaus.plexus.util.PathTool;
String relativeFilePath = PathTool.getRelativeFilePath(file1, file2);
实际上,如果目标路径不是基路径的子路径,我的另一个答案是不成立的。
这应该有用。
public class RelativePathFinder {
public static String getRelativePath(String targetPath, String basePath,
String pathSeparator) {
// find common path
String[] target = targetPath.split(pathSeparator);
String[] base = basePath.split(pathSeparator);
String common = "";
int commonIndex = 0;
for (int i = 0; i < target.length && i < base.length; i++) {
if (target[i].equals(base[i])) {
common += target[i] + pathSeparator;
commonIndex++;
}
}
String relative = "";
// is the target a child directory of the base directory?
// i.e., target = /a/b/c/d, base = /a/b/
if (commonIndex == base.length) {
relative = "." + pathSeparator + targetPath.substring(common.length());
}
else {
// determine how many directories we have to backtrack
for (int i = 1; i <= commonIndex; i++) {
relative += ".." + pathSeparator;
}
relative += targetPath.substring(common.length());
}
return relative;
}
public static String getRelativePath(String targetPath, String basePath) {
return getRelativePath(targetPath, basePath, File.pathSeparator);
}
}
public class RelativePathFinderTest extends TestCase {
public void testGetRelativePath() {
assertEquals("./stuff/xyz.dat", RelativePathFinder.getRelativePath(
"/var/data/stuff/xyz.dat", "/var/data/", "/"));
assertEquals("../../b/c", RelativePathFinder.getRelativePath("/a/b/c",
"/a/x/y/", "/"));
}
}
在另一个答案中提到的错误是由Apache HttpComponents中的URIUtils解决的
public static URI resolve(URI baseURI,
String reference)
对象的URI引用 基本URI。解决bug的方法 java.net.URI ()