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

static Charset	CHARSET_UTF_8 UTF-8 Charset instance to prevent repeated Charset.forName(String) lookups
static String	UTF_8 UTF-8 charset string

Method Summary

static void	close(Closeable... objects) Closes all given Closeables.
static void	close(Iterable<? extends Closeable> objects)
static void	closeWhileHandlingException(Closeable... objects) Closes all given Closeables, suppressing all thrown exceptions.
static <E extends Exception> void	closeWhileHandlingException(E priorException, Closeable... objects) Closes all given Closeables, suppressing all thrown exceptions.
static <E extends Exception> void	closeWhileHandlingException(E priorException, Iterable<? extends Closeable> objects)
static void	closeWhileHandlingException(Iterable<? extends Closeable> objects)
static Reader	getDecodingReader(Class<?> clazz, String resource, Charset charSet) Opens a Reader for the given resource using a CharsetDecoder.
static Reader	getDecodingReader(File file, Charset charSet) Opens a Reader for the given File using a CharsetDecoder.
static Reader	getDecodingReader(InputStream stream, Charset charSet) Wrapping the given InputStream in a reader using a CharsetDecoder.

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

See Also:

Charset.forName(String), Constant Field Values

CHARSET_UTF_8

public static final Charset CHARSET_UTF_8

UTF-8 Charset instance to prevent repeated Charset.forName(String) lookups

Method Detail

closeWhileHandlingException

public static <E extends Exception> void closeWhileHandlingException(E priorException,
                                                                     Closeable... objects)
                                        throws E extends Exception,
                                               IOException

Closes all given Closeables, suppressing all thrown exceptions. Some of the Closeables may be null, they are ignored. After everything is closed, method either throws priorException, if one is supplied, or the first of suppressed exceptions, or completes normally.

Sample usage:

 Closeable resource1 = null, resource2 = null, resource3 = null;
 ExpectedException priorE = null;
 try {
   resource1 = ...; resource2 = ...; resource3 = ...; // Acquisition may throw ExpectedException
   ..do..stuff.. // May throw ExpectedException
 } catch (ExpectedException e) {
   priorE = e;
 } finally {
   closeSafely(priorE, resource1, resource2, resource3);
 }
 

Parameters:

priorException - null or an exception that will be rethrown after method completion

objects - objects to call close() on

Throws:

E extends Exception

IOException

closeWhileHandlingException

public static <E extends Exception> void closeWhileHandlingException(E priorException,
                                                                     Iterable<? extends Closeable> objects)
                                        throws E extends Exception,
                                               IOException

Throws:

E extends Exception

IOException

See Also:

closeWhileHandlingException(Exception, Closeable...)

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

Throws:

IOException

See Also:

close(Closeable...)

closeWhileHandlingException

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

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

Throws:

IOException

closeWhileHandlingException

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

Throws:

IOException

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, its 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(File file,
                                       Charset charSet)
                                throws IOException

Opens a Reader for the given File 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, its not recommended to use as a common purpose reader.

Parameters:

file - the file to open a reader on

charSet - the expected charset

Returns:

a reader to read the given file

Throws:

IOException

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, its 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