org.apache.lucene.util

Class IOUtils

java.lang.Object

org.apache.lucene.util.IOUtils

public final class IOUtils
extends Object

This class emulates the new Java 7 "Try-With-Resources" statement. Remove once Lucene is on Java 7.

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

Field Summary

Fields

Modifier and Type	Field and Description
static String	UTF_8 UTF-8 charset string.

Method Summary

Modifier and Type	Method and Description
static void	close(Closeable... objects) Closes all given Closeables.
static void	close(Iterable<? extends Closeable> objects) Closes all given Closeables.
static void	closeWhileHandlingException(Closeable... objects) Closes all given Closeables, suppressing all thrown exceptions.
static void	closeWhileHandlingException(Iterable<? extends Closeable> objects) Closes all given Closeables, suppressing all thrown exceptions.
static void	deleteFiles(Directory dir, Collection<String> names) Deletes all given file names.
static void	deleteFiles(Directory dir, String... files)
static void	deleteFilesIfExist(Collection<? extends Path> files) Deletes all given Paths, if they exist.
static void	deleteFilesIfExist(Path... files) Deletes all given Paths, if they exist.
static void	deleteFilesIgnoringExceptions(Collection<? extends Path> files) Deletes all given files, suppressing all thrown IOExceptions.
static void	deleteFilesIgnoringExceptions(Directory dir, Collection<String> files) Deletes all given files, suppressing all thrown IOExceptions.
static void	deleteFilesIgnoringExceptions(Directory dir, String... files)
static void	deleteFilesIgnoringExceptions(Path... files) Deletes all given files, suppressing all thrown IOExceptions.
static void	fsync(Path fileToSync, boolean isDir) Ensure that any writes to the given file is written to the storage device that contains it.
static Reader	getDecodingReader(Class<?> clazz, String resource, Charset charSet) Opens a Reader for the given resource using a CharsetDecoder.
static Reader	getDecodingReader(InputStream stream, Charset charSet) Wrapping the given InputStream in a reader using a CharsetDecoder.
static void	reThrow(Throwable th) Simple utility method that takes a previously caught Throwable and rethrows either IOException or an unchecked exception.
static void	reThrowUnchecked(Throwable th) Simple utility method that takes a previously caught Throwable and rethrows it as an unchecked exception.
static void	rm(Path... locations) Deletes one or more files or directories (and everything underneath it).
static boolean	spins(Directory dir) If the dir is an FSDirectory or wraps one via possibly nested FilterDirectory or FileSwitchDirectory, this returns spins(Path) for the wrapped directory, else, true.
static boolean	spins(Path path) Rough Linux-only heuristics to determine whether the provided Path is backed by spinning storage.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

UTF_8

public static final String UTF_8

UTF-8 charset string.

Where possible, use StandardCharsets.UTF_8 instead, as using the String constant may slow things down.

See Also:

StandardCharsets.UTF_8

Method Detail

close

public static void close(Closeable... objects)
                  throws IOException

Closes all given Closeables. Some of the Closeables may be null; they are ignored. After everything is closed, the method either throws the first exception it hit while closing, or completes normally if there were no exceptions.

Parameters:

objects - objects to call close() on

Throws:

IOException

close

public static void close(Iterable<? extends Closeable> objects)
                  throws IOException

Closes all given Closeables.

Throws:

IOException

See Also:

close(Closeable...)

closeWhileHandlingException

public static void closeWhileHandlingException(Closeable... objects)

Closes all given Closeables, suppressing all thrown exceptions. Some of the Closeables may be null, they are ignored.

Parameters:

objects - objects to call close() on

closeWhileHandlingException

public static void closeWhileHandlingException(Iterable<? extends Closeable> objects)

Closes all given Closeables, suppressing all thrown exceptions.

See Also:

closeWhileHandlingException(Closeable...)

getDecodingReader

public static Reader getDecodingReader(InputStream stream,
                                       Charset charSet)

Wrapping the given InputStream in a reader using a CharsetDecoder. Unlike Java's defaults this reader will throw an exception if your it detects the read charset doesn't match the expected Charset.

Decoding readers are useful to load configuration files, stopword lists or synonym files to detect character set problems. However, it's not recommended to use as a common purpose reader.

Parameters:

stream - the stream to wrap in a reader

charSet - the expected charset

Returns:

a wrapping reader

getDecodingReader

public static Reader getDecodingReader(Class<?> clazz,
                                       String resource,
                                       Charset charSet)
                                throws IOException

Opens a Reader for the given resource using a CharsetDecoder. Unlike Java's defaults this reader will throw an exception if your it detects the read charset doesn't match the expected Charset.

Decoding readers are useful to load configuration files, stopword lists or synonym files to detect character set problems. However, it's not recommended to use as a common purpose reader.

Parameters:

clazz - the class used to locate the resource

resource - the resource name to load

charSet - the expected charset

Returns:

a reader to read the given file

Throws:

IOException

deleteFilesIgnoringExceptions

public static void deleteFilesIgnoringExceptions(Directory dir,
                                                 Collection<String> files)

Deletes all given files, suppressing all thrown IOExceptions.

Note that the files should not be null.

deleteFilesIgnoringExceptions

public static void deleteFilesIgnoringExceptions(Directory dir,
                                                 String... files)

deleteFiles

public static void deleteFiles(Directory dir,
                               Collection<String> names)
                        throws IOException

Deletes all given file names. Some of the file names may be null; they are ignored. After everything is deleted, the method either throws the first exception it hit while deleting, or completes normally if there were no exceptions.

Parameters:

dir - Directory to delete files from

names - file names to delete

Throws:

IOException

deleteFiles

public static void deleteFiles(Directory dir,
                               String... files)
                        throws IOException

Throws:

IOException

deleteFilesIgnoringExceptions

public static void deleteFilesIgnoringExceptions(Path... files)

Deletes all given files, suppressing all thrown IOExceptions.

Some of the files may be null, if so they are ignored.

deleteFilesIgnoringExceptions

public static void deleteFilesIgnoringExceptions(Collection<? extends Path> files)

Deletes all given files, suppressing all thrown IOExceptions.

Some of the files may be null, if so they are ignored.

deleteFilesIfExist

public static void deleteFilesIfExist(Path... files)
                               throws IOException

Deletes all given Paths, if they exist. Some of the Files may be null; they are ignored. After everything is deleted, the method either throws the first exception it hit while deleting, or completes normally if there were no exceptions.

Parameters:

files - files to delete

Throws:

IOException

deleteFilesIfExist

public static void deleteFilesIfExist(Collection<? extends Path> files)
                               throws IOException

Deletes all given Paths, if they exist. Some of the Files may be null; they are ignored. After everything is deleted, the method either throws the first exception it hit while deleting, or completes normally if there were no exceptions.

Parameters:

files - files to delete

Throws:

IOException

rm

public static void rm(Path... locations)
               throws IOException

Deletes one or more files or directories (and everything underneath it).

Throws:

IOException - if any of the given files (or their subhierarchy files in case of directories) cannot be removed.

reThrow

public static void reThrow(Throwable th)
                    throws IOException

Simple utility method that takes a previously caught Throwable and rethrows either IOException or an unchecked exception. If the argument is null then this method does nothing.

Throws:

IOException

reThrowUnchecked

public static void reThrowUnchecked(Throwable th)

Simple utility method that takes a previously caught Throwable and rethrows it as an unchecked exception. If the argument is null then this method does nothing.

fsync

public static void fsync(Path fileToSync,
                         boolean isDir)
                  throws IOException

Ensure that any writes to the given file is written to the storage device that contains it.

Parameters:

fileToSync - the file to fsync

isDir - if true, the given file is a directory (we open for read and ignore IOExceptions, because not all file systems and operating systems allow to fsync on a directory)

Throws:

IOException

spins

public static boolean spins(Directory dir)
                     throws IOException

If the dir is an FSDirectory or wraps one via possibly nested FilterDirectory or FileSwitchDirectory, this returns spins(Path) for the wrapped directory, else, true.

Throws:

IOException - if path does not exist.

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

spins

public static boolean spins(Path path)
                     throws IOException

Rough Linux-only heuristics to determine whether the provided Path is backed by spinning storage. For example, this returns false if the disk is a solid-state disk.

Parameters:

path - a location to check which must exist. the mount point will be determined from this location.

Returns:

false if the storage is non-rotational (e.g. an SSD), or true if it is spinning or could not be determined

Throws:

IOException - if path does not exist.

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.