Java: 检查路径是否为文件的 parent

Question

我似乎找不到解决办法。

我有两条路，比如：

D:/Views/me/a.b 和 D:/Views/me/a

或

D:/Views/me/a.b 和 D:/Views/me/a.b/x/y

我必须确保一个 file/directory 不是另一个的 child。我试过 Contains 但在这种情况下它对我不起作用？

Answer 1

尝试使用字符串的 startsWith api：

String str1 = "D:/Views/me/a.b";
String str2 = "D:/Views/me/a";
if (str1.startsWith(str2 + ".") || str1.startsWith(str2 + "/")) {
    System.out.println("Yes it is");
}
str1 = "D:/Views/me/a/c/d";
str2 = "D:/Views/me/a";
if (str1.startsWith(str2 + ".") || str1.startsWith(str2 + "/")) {
     System.out.println("Yes it is");
}
Output:
Yes it is
Yes it is

Answer 2

    String path = "D:/Views/me/a.b";
    String path2 = "D:/Views/me/a";
    File file = new File(path);
    if(file.getParentFile().getAbsolutePath().equals("path2")){
    System.out.println("file is parent");
    }else{
        System.out.println("file is not parent");
    }

Answer 3

我认为 java.nio.file 中的 Path and Paths 在这里很有用（如果你至少有 Java 7）。

public static void main(String[] args) {
    Path p1 = Paths.get("D:/Views/me/a.b");
    Path p2 = Paths.get("D:/Views/me/a");
    System.out.println(isChild(p1, p2));
    System.out.println(isChild(p2, p1));

    Path p3 = Paths.get("D:/Views/me/a.b");
    Path p4 = Paths.get("D:/Views/me/a.b/x/y");
    System.out.println(isChild(p3, p4));
    System.out.println(isChild(p4, p3));
}

//Check if childCandidate is child of path
public static boolean isChild(Path path, Path childCandidate) {
    return childCandidate.startsWith(path);
}

您可以根据需要考虑在检查前的路径上使用 toAbsolutePath() 或 toRealPath()。

这是 Path Operations 的官方 Java 教程。

Answer 4

令人惊讶的是，没有简单但实用的解决方案。

这是仅使用 java.nio.file.Path API 的一个：

static boolean isChildPath(Path parent, Path child){
      Path pn = parent.normalize();
      Path cn = child.normalize();
      return cn.getNameCount() > pn.getNameCount() && cn.startsWith(pn);
}

测试用例：

 @Test
public void testChildPath() {
      assertThat(isChildPath(Paths.get("/FolderA/FolderB/F"), Paths.get("/FolderA/FolderB/F"))).isFalse();
      assertThat(isChildPath(Paths.get("/FolderA/FolderB/F"), Paths.get("/FolderA/FolderB/F/A"))).isTrue();
      assertThat(isChildPath(Paths.get("/FolderA/FolderB/F"), Paths.get("/FolderA/FolderB/F/A.txt"))).isTrue();

      assertThat(isChildPath(Paths.get("/FolderA/FolderB/F"), Paths.get("/FolderA/FolderB/F/../A"))).isFalse();
      assertThat(isChildPath(Paths.get("/FolderA/FolderB/F"), Paths.get("/FolderA/FolderB/FA"))).isFalse();

      assertThat(isChildPath(Paths.get("FolderA"), Paths.get("FolderA"))).isFalse();
      assertThat(isChildPath(Paths.get("FolderA"), Paths.get("FolderA/B"))).isTrue();
      assertThat(isChildPath(Paths.get("FolderA"), Paths.get("FolderA/B"))).isTrue();
      assertThat(isChildPath(Paths.get("FolderA"), Paths.get("FolderAB"))).isFalse();
      assertThat(isChildPath(Paths.get("/FolderA/FolderB/F"), Paths.get("/FolderA/FolderB/F/Z/X/../A"))).isTrue();
}

Java: 检查路径是否为文件的 parent

Java: Check if path is parent of a file

java

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filepath