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
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)
其他回答
如果你知道第二个字符串是第一个字符串的一部分:
String s1 = "/var/data/stuff/xyz.dat";
String s2 = "/var/data";
String s3 = s1.substring(s2.length());
或者,如果你真的想把句号放在开头,就像你的例子中那样:
String s3 = ".".concat(s1.substring(s2.length()));
这里已经有很多答案了,但我发现他们并不能处理所有的情况,比如基地和目标是相同的。这个函数接受一个基本目录和一个目标路径,并返回相对路径。如果不存在相对路径,则返回目标路径。文件。分隔符是不必要的。
public static String getRelativePath (String baseDir, String targetPath) {
String[] base = baseDir.replace('\\', '/').split("\\/");
targetPath = targetPath.replace('\\', '/');
String[] target = targetPath.split("\\/");
// Count common elements and their length.
int commonCount = 0, commonLength = 0, maxCount = Math.min(target.length, base.length);
while (commonCount < maxCount) {
String targetElement = target[commonCount];
if (!targetElement.equals(base[commonCount])) break;
commonCount++;
commonLength += targetElement.length() + 1; // Directory name length plus slash.
}
if (commonCount == 0) return targetPath; // No common path element.
int targetLength = targetPath.length();
int dirsUp = base.length - commonCount;
StringBuffer relative = new StringBuffer(dirsUp * 3 + targetLength - commonLength + 1);
for (int i = 0; i < dirsUp; i++)
relative.append("../");
if (commonLength < targetLength) relative.append(targetPath.substring(commonLength));
return relative.toString();
}
下面是一个从基本路径解析相对路径的方法,不管它们在相同或不同的根路径中:
public static String GetRelativePath(String path, String base){
final String SEP = "/";
// if base is not a directory -> return empty
if (!base.endsWith(SEP)){
return "";
}
// check if path is a file -> remove last "/" at the end of the method
boolean isfile = !path.endsWith(SEP);
// get URIs and split them by using the separator
String a = "";
String b = "";
try {
a = new File(base).getCanonicalFile().toURI().getPath();
b = new File(path).getCanonicalFile().toURI().getPath();
} catch (IOException e) {
e.printStackTrace();
}
String[] basePaths = a.split(SEP);
String[] otherPaths = b.split(SEP);
// check common part
int n = 0;
for(; n < basePaths.length && n < otherPaths.length; n ++)
{
if( basePaths[n].equals(otherPaths[n]) == false )
break;
}
// compose the new path
StringBuffer tmp = new StringBuffer("");
for(int m = n; m < basePaths.length; m ++)
tmp.append(".."+SEP);
for(int m = n; m < otherPaths.length; m ++)
{
tmp.append(otherPaths[m]);
tmp.append(SEP);
}
// get path string
String result = tmp.toString();
// remove last "/" if path is a file
if (isfile && result.endsWith(SEP)){
result = result.substring(0,result.length()-1);
}
return result;
}
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/", "/"));
}
}
Psuedo-code:
使用路径分隔符("/")拆分字符串 通过迭代拆分字符串的结果来找到最大的公共路径(因此在两个示例中,您最终会得到"/var/data"或"/a") 返回“。”+ whicheverPathIsLonger.substring (commonPath.length);