以下是该示例的链接： https://docs.oracle.com/javase/tutorial/essential/io/examples/Chmod.java
此示例中的代码如下：
import java.nio.file.*;
import java.nio.file.attribute.*;
import static java.nio.file.attribute.PosixFilePermission.*;
import static java.nio.file.FileVisitResult.*;
import java.io.IOException;
import java.util.*;
public class Chmod {
public static Changer compile(String exprs) {
// minimum is who and operator (u= for example)
if (exprs.length() < 2)
throw new IllegalArgumentException("Invalid mode");
// permissions that the changer will add or remove
final Set<PosixFilePermission> toAdd = new HashSet<PosixFilePermission>();
final Set<PosixFilePermission> toRemove = new HashSet<PosixFilePermission>();
// iterate over each of expression modes
for (String expr: exprs.split(",")) {
// minimum of who and operator
if (expr.length() < 2)
throw new IllegalArgumentException("Invalid mode");
int pos = 0;
// who
boolean u = false;
boolean g = false;
boolean o = false;
boolean done = false;
for (;;) {
switch (expr.charAt(pos)) {
case 'u' : u = true; break;
case 'g' : g = true; break;
case 'o' : o = true; break;
case 'a' : u = true; g = true; o = true; break;
default : done = true;
}
if (done)
break;
pos++;
}
if (!u && !g && !o)
throw new IllegalArgumentException("Invalid mode");
// get operator and permissions
char op = expr.charAt(pos++);
String mask = (expr.length() == pos) ? "" : expr.substring(pos);
// operator
boolean add = (op == '+');
boolean remove = (op == '-');
boolean assign = (op == '=');
if (!add && !remove && !assign)
throw new IllegalArgumentException("Invalid mode");
// who= means remove all
if (assign && mask.length() == 0) {
assign = false;
remove = true;
mask = "rwx";
}
// permissions
boolean r = false;
boolean w = false;
boolean x = false;
for (int i=0; i<mask.length(); i++) {
switch (mask.charAt(i)) {
case 'r' : r = true; break;
case 'w' : w = true; break;
case 'x' : x = true; break;
default:
throw new IllegalArgumentException("Invalid mode");
}
}
// update permissions set
if (add) {
if (u) {
if (r) toAdd.add(OWNER_READ);
if (w) toAdd.add(OWNER_WRITE);
if (x) toAdd.add(OWNER_EXECUTE);
}
if (g) {
if (r) toAdd.add(GROUP_READ);
if (w) toAdd.add(GROUP_WRITE);
if (x) toAdd.add(GROUP_EXECUTE);
}
if (o) {
if (r) toAdd.add(OTHERS_READ);
if (w) toAdd.add(OTHERS_WRITE);
if (x) toAdd.add(OTHERS_EXECUTE);
}
}
if (remove) {
if (u) {
if (r) toRemove.add(OWNER_READ);
if (w) toRemove.add(OWNER_WRITE);
if (x) toRemove.add(OWNER_EXECUTE);
}
if (g) {
if (r) toRemove.add(GROUP_READ);
if (w) toRemove.add(GROUP_WRITE);
if (x) toRemove.add(GROUP_EXECUTE);
}
if (o) {
if (r) toRemove.add(OTHERS_READ);
if (w) toRemove.add(OTHERS_WRITE);
if (x) toRemove.add(OTHERS_EXECUTE);
}
}
if (assign) {
if (u) {
if (r) toAdd.add(OWNER_READ);
else toRemove.add(OWNER_READ);
if (w) toAdd.add(OWNER_WRITE);
else toRemove.add(OWNER_WRITE);
if (x) toAdd.add(OWNER_EXECUTE);
else toRemove.add(OWNER_EXECUTE);
}
if (g) {
if (r) toAdd.add(GROUP_READ);
else toRemove.add(GROUP_READ);
if (w) toAdd.add(GROUP_WRITE);
else toRemove.add(GROUP_WRITE);
if (x) toAdd.add(GROUP_EXECUTE);
else toRemove.add(GROUP_EXECUTE);
}
if (o) {
if (r) toAdd.add(OTHERS_READ);
else toRemove.add(OTHERS_READ);
if (w) toAdd.add(OTHERS_WRITE);
else toRemove.add(OTHERS_WRITE);
if (x) toAdd.add(OTHERS_EXECUTE);
else toRemove.add(OTHERS_EXECUTE);
}
}
}
// return changer
return new Changer() {
@Override
public Set<PosixFilePermission> change(Set<PosixFilePermission> perms) {
perms.addAll(toAdd);
perms.removeAll(toRemove);
return perms;
}
};
}
/**
* A task that <i>changes</i> a set of {@link PosixFilePermission} elements.
*/
public interface Changer {
/**
* Applies the changes to the given set of permissions.
*
* @param perms
* The set of permissions to change
*
* @return The {@code perms} parameter
*/
Set<PosixFilePermission> change(Set<PosixFilePermission> perms);
}
/**
* Changes the permissions of the file using the given Changer.
*/
static void chmod(Path file, Changer changer) {
try {
Set<PosixFilePermission> perms = Files.getPosixFilePermissions(file);
Files.setPosixFilePermissions(file, changer.change(perms));
} catch (IOException x) {
System.err.println(x);
}
}
/**
* Changes the permission of each file and directory visited
*/
static class TreeVisitor implements FileVisitor<Path> {
private final Changer changer;
TreeVisitor(Changer changer) {
this.changer = changer;
}
@Override
public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
chmod(dir, changer);
return CONTINUE;
}
@Override
public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
chmod(file, changer);
return CONTINUE;
}
@Override
public FileVisitResult postVisitDirectory(Path dir, IOException exc) {
if (exc != null)
System.err.println("WARNING: " + exc);
return CONTINUE;
}
@Override
public FileVisitResult visitFileFailed(Path file, IOException exc) {
System.err.println("WARNING: " + exc);
return CONTINUE;
}
}
static void usage() {
System.err.println("java Chmod [-R] symbolic-mode-list file...");
System.exit(-1);
}
public static void main(String[] args) throws IOException {
if (args.length < 2)
usage();
int argi = 0;
int maxDepth = 0;
if (args[argi].equals("-R")) {
if (args.length < 3)
usage();
argi++;
maxDepth = Integer.MAX_VALUE;
}
// compile the symbolic mode expressions
Changer changer = compile(args[argi++]);
TreeVisitor visitor = new TreeVisitor(changer);
Set<FileVisitOption> opts = Collections.emptySet();
while (argi < args.length) {
Path file = Paths.get(args[argi]);
Files.walkFileTree(file, opts, maxDepth, visitor);
argi++;
}
}
}
首先我使用的是Netbeans IDE。我对chmod的工作原理知之甚少，因为我不是linux用户。 这个chmod.java应该如何工作？基本上你不需要解释所有内容，因为如果代码已经有效，我将自己学习。
以下是我在netbeans上试过的论据
-R u+w,o-rwx C:\Users\Josh\Desktop\chin.txt
但它给出了错误
Exception in thread "main" java.lang.UnsupportedOperationException
at sun.nio.fs.WindowsFileSystemProvider.readAttributes(WindowsFileSystemProvider.java:192)
at java.nio.file.Files.readAttributes(Files.java:1737)
at java.nio.file.Files.getPosixFilePermissions(Files.java:2004)
at chmod.Chmod.chmod(Chmod.java:269)
at chmod.Chmod$TreeVisitor.visitFile(Chmod.java:294)
at chmod.Chmod$TreeVisitor.visitFile(Chmod.java:279)
at java.nio.file.Files.walkFileTree(Files.java:2670)
at chmod.Chmod.main(Chmod.java:336)
Java结果：1
答案 0 :(得分：1)
您使用的是Windows文件系统，chmod需要一个支持POSIX的文件系统; Windows，嗯，没有。
作为证明，请尝试并执行此操作：
final FileSystem fs = FileSystems.getDefault(); // <-- that's your filesystem
System.out.println(fs.supportedFileAttributeViews());
您不会看到posix显示。
如果您想玩它，请尝试使用memoryfilesystem，它有办法构建具有类Unix功能的FileSystem：
final FileSystem fs = MemoryFileSystemBuilder.newLinux()
.build("testfs");
// fs.getPath() etc
另请查看this project，您可以使用它来执行此操作：
MoreFiles.setMode(somePath, 0644); // for instance