org.h2.store.fs.FilePath Maven / Gradle / Ivy
/*
* Copyright 2004-2019 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.store.fs;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.channels.FileChannel;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import org.h2.util.MathUtils;
/**
* A path to a file. It similar to the Java 7 java.nio.file.Path,
* but simpler, and works with older versions of Java. It also implements the
* relevant methods found in java.nio.file.FileSystem and
* FileSystems
*/
public abstract class FilePath {
private static FilePath defaultProvider;
private static ConcurrentHashMap providers;
/**
* The prefix for temporary files.
*/
private static String tempRandom;
private static long tempSequence;
/**
* The complete path (which may be absolute or relative, depending on the
* file system).
*/
protected String name;
/**
* Get the file path object for the given path.
* Windows-style '\' is replaced with '/'.
*
* @param path the path
* @return the file path object
*/
public static FilePath get(String path) {
path = path.replace('\\', '/');
int index = path.indexOf(':');
registerDefaultProviders();
if (index < 2) {
// use the default provider if no prefix or
// only a single character (drive name)
return defaultProvider.getPath(path);
}
String scheme = path.substring(0, index);
FilePath p = providers.get(scheme);
if (p == null) {
// provider not found - use the default
p = defaultProvider;
}
return p.getPath(path);
}
private static void registerDefaultProviders() {
if (providers == null || defaultProvider == null) {
ConcurrentHashMap map = new ConcurrentHashMap<>();
for (String c : new String[] {
"org.h2.store.fs.FilePathDisk",
"org.h2.store.fs.FilePathMem",
"org.h2.store.fs.FilePathMemLZF",
"org.h2.store.fs.FilePathNioMem",
"org.h2.store.fs.FilePathNioMemLZF",
"org.h2.store.fs.FilePathSplit",
"org.h2.store.fs.FilePathNio",
"org.h2.store.fs.FilePathNioMapped",
"org.h2.store.fs.FilePathAsync",
"org.h2.store.fs.FilePathZip",
"org.h2.store.fs.FilePathRetryOnInterrupt"
}) {
try {
FilePath p = (FilePath) Class.forName(c).getDeclaredConstructor().newInstance();
map.put(p.getScheme(), p);
if (defaultProvider == null) {
defaultProvider = p;
}
} catch (Exception e) {
// ignore - the files may be excluded in purpose
}
}
providers = map;
}
}
/**
* Register a file provider.
*
* @param provider the file provider
*/
public static void register(FilePath provider) {
registerDefaultProviders();
providers.put(provider.getScheme(), provider);
}
/**
* Unregister a file provider.
*
* @param provider the file provider
*/
public static void unregister(FilePath provider) {
registerDefaultProviders();
providers.remove(provider.getScheme());
}
/**
* Get the size of a file in bytes
*
* @return the size in bytes
*/
public abstract long size();
/**
* Rename a file if this is allowed.
*
* @param newName the new fully qualified file name
* @param atomicReplace whether the move should be atomic, and the target
* file should be replaced if it exists and replacing is possible
*/
public abstract void moveTo(FilePath newName, boolean atomicReplace);
/**
* Create a new file.
*
* @return true if creating was successful
*/
public abstract boolean createFile();
/**
* Checks if a file exists.
*
* @return true if it exists
*/
public abstract boolean exists();
/**
* Delete a file or directory if it exists.
* Directories may only be deleted if they are empty.
*/
public abstract void delete();
/**
* List the files and directories in the given directory.
*
* @return the list of fully qualified file names
*/
public abstract List newDirectoryStream();
/**
* Normalize a file name.
*
* @return the normalized file name
*/
public abstract FilePath toRealPath();
/**
* Get the parent directory of a file or directory.
*
* @return the parent directory name
*/
public abstract FilePath getParent();
/**
* Check if it is a file or a directory.
*
* @return true if it is a directory
*/
public abstract boolean isDirectory();
/**
* Check if the file name includes a path.
*
* @return if the file name is absolute
*/
public abstract boolean isAbsolute();
/**
* Get the last modified date of a file
*
* @return the last modified date
*/
public abstract long lastModified();
/**
* Check if the file is writable.
*
* @return if the file is writable
*/
public abstract boolean canWrite();
/**
* Create a directory (all required parent directories already exist).
*/
public abstract void createDirectory();
/**
* Get the file or directory name (the last element of the path).
*
* @return the last element of the path
*/
public String getName() {
int idx = Math.max(name.indexOf(':'), name.lastIndexOf('/'));
return idx < 0 ? name : name.substring(idx + 1);
}
/**
* Create an output stream to write into the file.
*
* @param append if true, the file will grow, if false, the file will be
* truncated first
* @return the output stream
* @throws IOException If an I/O error occurs
*/
public abstract OutputStream newOutputStream(boolean append) throws IOException;
/**
* Open a random access file object.
*
* @param mode the access mode. Supported are r, rw, rws, rwd
* @return the file object
* @throws IOException If an I/O error occurs
*/
public abstract FileChannel open(String mode) throws IOException;
/**
* Create an input stream to read from the file.
*
* @return the input stream
* @throws IOException If an I/O error occurs
*/
public abstract InputStream newInputStream() throws IOException;
/**
* Disable the ability to write.
*
* @return true if the call was successful
*/
public abstract boolean setReadOnly();
/**
* Create a new temporary file.
*
* @param suffix the suffix
* @param inTempDir if the file should be stored in the temporary directory
* @return the name of the created file
*/
@SuppressWarnings("unused")
public FilePath createTempFile(String suffix, boolean inTempDir) throws IOException {
while (true) {
FilePath p = getPath(name + getNextTempFileNamePart(false) + suffix);
if (p.exists() || !p.createFile()) {
// in theory, the random number could collide
getNextTempFileNamePart(true);
continue;
}
p.open("rw").close();
return p;
}
}
/**
* Get the next temporary file name part (the part in the middle).
*
* @param newRandom if the random part of the filename should change
* @return the file name part
*/
protected static synchronized String getNextTempFileNamePart(
boolean newRandom) {
if (newRandom || tempRandom == null) {
tempRandom = MathUtils.randomInt(Integer.MAX_VALUE) + ".";
}
return tempRandom + tempSequence++;
}
/**
* Get the string representation. The returned string can be used to
* construct a new object.
*
* @return the path as a string
*/
@Override
public String toString() {
return name;
}
/**
* Get the scheme (prefix) for this file provider.
* This is similar to
* java.nio.file.spi.FileSystemProvider.getScheme.
*
* @return the scheme
*/
public abstract String getScheme();
/**
* Convert a file to a path. This is similar to
* java.nio.file.spi.FileSystemProvider.getPath, but may
* return an object even if the scheme doesn't match in case of the
* default file provider.
*
* @param path the path
* @return the file path object
*/
public abstract FilePath getPath(String path);
/**
* Get the unwrapped file name (without wrapper prefixes if wrapping /
* delegating file systems are used).
*
* @return the unwrapped path
*/
public FilePath unwrap() {
return this;
}
}