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
酷! !我需要一些类似这样的代码,但用于比较Linux机器上的目录路径。我发现这在父目录为目标的情况下不起作用。
下面是该方法的目录友好版本:
public static String getRelativePath(String targetPath, String basePath,
String pathSeparator) {
boolean isDir = false;
{
File f = new File(targetPath);
isDir = f.isDirectory();
}
// We need the -1 argument to split to make sure we get a trailing
// "" token if the base ends in the path separator and is therefore
// a directory. We require directory paths to end in the path
// separator -- otherwise they are indistinguishable from files.
String[] base = basePath.split(Pattern.quote(pathSeparator), -1);
String[] target = targetPath.split(Pattern.quote(pathSeparator), 0);
// First get all the common elements. Store them as a string,
// and also count how many of them there are.
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++;
}
else break;
}
if (commonIndex == 0)
{
// Whoops -- not even a single common path element. This most
// likely indicates differing drive letters, like C: and D:.
// These paths cannot be relativized. Return the target path.
return targetPath;
// This should never happen when all absolute paths
// begin with / as in *nix.
}
String relative = "";
if (base.length == commonIndex) {
// Comment this out if you prefer that a relative path not start with ./
relative = "." + pathSeparator;
}
else {
int numDirsUp = base.length - commonIndex - (isDir?0:1); /* only subtract 1 if it is a file. */
// The number of directories we have to backtrack is the length of
// the base path MINUS the number of common path elements, minus
// one because the last element in the path isn't a directory.
for (int i = 1; i <= (numDirsUp); i++) {
relative += ".." + pathSeparator;
}
}
//if we are comparing directories then we
if (targetPath.length() > common.length()) {
//it's OK, it isn't a directory
relative += targetPath.substring(common.length());
}
return relative;
}
其他回答
酷! !我需要一些类似这样的代码,但用于比较Linux机器上的目录路径。我发现这在父目录为目标的情况下不起作用。
下面是该方法的目录友好版本:
public static String getRelativePath(String targetPath, String basePath,
String pathSeparator) {
boolean isDir = false;
{
File f = new File(targetPath);
isDir = f.isDirectory();
}
// We need the -1 argument to split to make sure we get a trailing
// "" token if the base ends in the path separator and is therefore
// a directory. We require directory paths to end in the path
// separator -- otherwise they are indistinguishable from files.
String[] base = basePath.split(Pattern.quote(pathSeparator), -1);
String[] target = targetPath.split(Pattern.quote(pathSeparator), 0);
// First get all the common elements. Store them as a string,
// and also count how many of them there are.
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++;
}
else break;
}
if (commonIndex == 0)
{
// Whoops -- not even a single common path element. This most
// likely indicates differing drive letters, like C: and D:.
// These paths cannot be relativized. Return the target path.
return targetPath;
// This should never happen when all absolute paths
// begin with / as in *nix.
}
String relative = "";
if (base.length == commonIndex) {
// Comment this out if you prefer that a relative path not start with ./
relative = "." + pathSeparator;
}
else {
int numDirsUp = base.length - commonIndex - (isDir?0:1); /* only subtract 1 if it is a file. */
// The number of directories we have to backtrack is the length of
// the base path MINUS the number of common path elements, minus
// one because the last element in the path isn't a directory.
for (int i = 1; i <= (numDirsUp); i++) {
relative += ".." + pathSeparator;
}
}
//if we are comparing directories then we
if (targetPath.length() > common.length()) {
//it's OK, it isn't a directory
relative += targetPath.substring(common.length());
}
return relative;
}
递归产生一个较小的解决方案。如果结果不可能(例如不同的Windows磁盘)或不切实际(根目录只是普通目录),则抛出异常。
/**
* Computes the path for a file relative to a given base, or fails if the only shared
* directory is the root and the absolute form is better.
*
* @param base File that is the base for the result
* @param name File to be "relativized"
* @return the relative name
* @throws IOException if files have no common sub-directories, i.e. at best share the
* root prefix "/" or "C:\"
*/
public static String getRelativePath(File base, File name) throws IOException {
File parent = base.getParentFile();
if (parent == null) {
throw new IOException("No common directory");
}
String bpath = base.getCanonicalPath();
String fpath = name.getCanonicalPath();
if (fpath.startsWith(bpath)) {
return fpath.substring(bpath.length() + 1);
} else {
return (".." + File.separator + getRelativePath(parent, name));
}
}
private String relative(String left, String right){
String[] lefts = left.split("/");
String[] rights = right.split("/");
int min = Math.min(lefts.length, rights.length);
int commonIdx = -1;
for(int i = 0; i < min; i++){
if(commonIdx < 0 && !lefts[i].equals(rights[i])){
commonIdx = i - 1;
break;
}
}
if(commonIdx < 0){
return null;
}
StringBuilder sb = new StringBuilder(Math.max(left.length(), right.length()));
sb.append(left).append("/");
for(int i = commonIdx + 1; i < lefts.length;i++){
sb.append("../");
}
for(int i = commonIdx + 1; i < rights.length;i++){
sb.append(rights[i]).append("/");
}
return sb.deleteCharAt(sb.length() -1).toString();
}
ant有一个带有getRelativePath方法的FileUtils类。我自己还没有尝试过,但是值得一试。
http://javadoc.haefelinger.it/org.apache.ant/1.7.1/org/apache/tools/ant/util/FileUtils.html getRelativePath (java.io.File java.io.File)
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 ()