public class IOUtils extends Object
This class provides static utility methods for input/output operations.
The byte-to-char methods and char-to-byte methods involve a conversion step. Two methods are provided in each case, one that uses the platform default encoding and the other which allows you to specify an encoding. You are encouraged to always specify an encoding because relying on the platform default can lead to unexpected results, for example when moving from development to production.
All the methods in this class that read a stream are buffered internally.
This means that there is no cause to use a BufferedInputStream
or BufferedReader. The default buffer size of 4K has been shown
to be efficient in tests.
Wherever possible, the methods in this class do not flush or close the stream. This is to avoid making non-portable assumptions about the streams' origin and further use. Thus the caller is still responsible for closing streams after use.
Origin of code: Excalibur.
| Modifier and Type | Field and Description |
|---|---|
static char |
DIR_SEPARATOR
The system directory separator character.
|
static char |
DIR_SEPARATOR_UNIX
The Unix directory separator character.
|
static char |
DIR_SEPARATOR_WINDOWS
The Windows directory separator character.
|
static String |
LINE_SEPARATOR
The system line separator string.
|
static String |
LINE_SEPARATOR_UNIX
The Unix line separator string.
|
static String |
LINE_SEPARATOR_WINDOWS
The Windows line separator string.
|
| Constructor and Description |
|---|
IOUtils()
Instances should NOT be constructed in standard programming.
|
| Modifier and Type | Method and Description |
|---|---|
static void |
closeQuietly(Closeable closeable)
Unconditionally close a
Closeable. |
static void |
closeQuietly(InputStream input)
Unconditionally close an
InputStream. |
static void |
closeQuietly(OutputStream output)
Unconditionally close an
OutputStream. |
static boolean |
contentEquals(InputStream input1,
InputStream input2)
Compare the contents of two Streams to determine if they are equal or
not.
|
static int |
copy(InputStream input,
OutputStream output)
Copy bytes from an
InputStream to an
OutputStream. |
static void |
copy(InputStream input,
Writer output)
Copy bytes from an
InputStream to chars on a
Writer using the default character encoding of the platform. |
static void |
copy(InputStream input,
Writer output,
String encoding)
Copy bytes from an
InputStream to chars on a
Writer using the specified character encoding. |
static int |
copy(Reader input,
Writer output)
Copy chars from a
Reader to a Writer. |
static long |
copyLarge(InputStream input,
OutputStream output)
Copy bytes from a large (over 2GB)
InputStream to an
OutputStream. |
static long |
copyLarge(InputStream input,
OutputStream output,
byte[] buffer)
Copy bytes from a large (over 2GB)
InputStream to an
OutputStream. |
static long |
copyLarge(Reader input,
Writer output)
Copy chars from a large (over 2GB)
Reader to a Writer. |
static long |
copyLarge(Reader input,
Writer output,
char[] buffer)
Copy chars from a large (over 2GB)
Reader to a Writer. |
static byte[] |
toByteArray(InputStream input)
Get the contents of an
InputStream as a byte[]. |
static String |
toString(InputStream input,
String encoding)
Get the contents of an
InputStream as a String
using the specified character encoding. |
public static final char DIR_SEPARATOR_UNIX
public static final char DIR_SEPARATOR_WINDOWS
public static final char DIR_SEPARATOR
public static final String LINE_SEPARATOR_UNIX
public static final String LINE_SEPARATOR_WINDOWS
public static final String LINE_SEPARATOR
public IOUtils()
public static void closeQuietly(InputStream input)
InputStream.
Equivalent to InputStream.close(), except any exceptions will be ignored.
This is typically used in finally blocks.
Example code:
byte[] data = new byte[1024];
InputStream in = null;
try {
in = new FileInputStream("foo.txt");
in.read(data);
in.close(); //close errors are handled
} catch (Exception e) {
// error handling
} finally {
IOUtils.closeQuietly(in);
}
input - the InputStream to close, may be null or already closedpublic static void closeQuietly(OutputStream output)
OutputStream.
Equivalent to OutputStream.close(), except any exceptions will be ignored.
This is typically used in finally blocks.
Example code:
byte[] data = "Hello, World".getBytes();
OutputStream out = null;
try {
out = new FileOutputStream("foo.txt");
out.write(data);
out.close(); //close errors are handled
} catch (IOException e) {
// error handling
} finally {
IOUtils.closeQuietly(out);
}
output - the OutputStream to close, may be null or already closedpublic static void closeQuietly(Closeable closeable)
Closeable.
Equivalent to Closeable.close(), except any exceptions will be ignored.
This is typically used in finally blocks.
Example code:
Closeable closeable = null;
try {
closeable = new FileReader("foo.txt");
// process closeable
closeable.close();
} catch (Exception e) {
// error handling
} finally {
IOUtils.closeQuietly(closeable);
}
closeable - the object to close, may be null or already closedpublic static byte[] toByteArray(InputStream input) throws IOException
InputStream as a byte[].
This method buffers the input internally, so there is no need to use a
BufferedInputStream.
input - the InputStream to read fromNullPointerException - if the input is nullIOException - if an I/O error occurspublic static String toString(InputStream input, String encoding) throws IOException
InputStream as a String
using the specified character encoding.
Character encoding names can be found at IANA.
This method buffers the input internally, so there is no need to use a
BufferedInputStream.
input - the InputStream to read fromencoding - the encoding to use, null means platform defaultNullPointerException - if the input is nullIOException - if an I/O error occurspublic static int copy(InputStream input, OutputStream output) throws IOException
InputStream to an
OutputStream.
This method buffers the input internally, so there is no need to use a
BufferedInputStream.
Large streams (over 2GB) will return a bytes copied value of
-1 after the copy has completed since the correct
number of bytes cannot be returned as an int. For large streams
use the copyLarge(InputStream, OutputStream) method.
input - the InputStream to read fromoutput - the OutputStream to write toNullPointerException - if the input or output is nullIOException - if an I/O error occurspublic static long copyLarge(InputStream input, OutputStream output) throws IOException
InputStream to an
OutputStream.
This method buffers the input internally, so there is no need to use a
BufferedInputStream.
The buffer size is given by DEFAULT_BUFFER_SIZE.
input - the InputStream to read fromoutput - the OutputStream to write toNullPointerException - if the input or output is nullIOException - if an I/O error occurspublic static long copyLarge(InputStream input, OutputStream output, byte[] buffer) throws IOException
InputStream to an
OutputStream.
This method uses the provided buffer, so there is no need to use a
BufferedInputStream.
input - the InputStream to read fromoutput - the OutputStream to write tobuffer - the buffer to use for the copyNullPointerException - if the input or output is nullIOException - if an I/O error occurspublic static void copy(InputStream input, Writer output) throws IOException
InputStream to chars on a
Writer using the default character encoding of the platform.
This method buffers the input internally, so there is no need to use a
BufferedInputStream.
This method uses InputStreamReader.
input - the InputStream to read fromoutput - the Writer to write toNullPointerException - if the input or output is nullIOException - if an I/O error occurspublic static void copy(InputStream input, Writer output, String encoding) throws IOException
InputStream to chars on a
Writer using the specified character encoding.
This method buffers the input internally, so there is no need to use a
BufferedInputStream.
Character encoding names can be found at IANA.
This method uses InputStreamReader.
input - the InputStream to read fromoutput - the Writer to write toencoding - the encoding to use, null means platform defaultNullPointerException - if the input or output is nullIOException - if an I/O error occurspublic static int copy(Reader input, Writer output) throws IOException
Reader to a Writer.
This method buffers the input internally, so there is no need to use a
BufferedReader.
Large streams (over 2GB) will return a chars copied value of
-1 after the copy has completed since the correct
number of chars cannot be returned as an int. For large streams
use the copyLarge(Reader, Writer) method.
input - the Reader to read fromoutput - the Writer to write toNullPointerException - if the input or output is nullIOException - if an I/O error occurspublic static long copyLarge(Reader input, Writer output) throws IOException
Reader to a Writer.
This method buffers the input internally, so there is no need to use a
BufferedReader.
The buffer size is given by DEFAULT_BUFFER_SIZE.
input - the Reader to read fromoutput - the Writer to write toNullPointerException - if the input or output is nullIOException - if an I/O error occurspublic static long copyLarge(Reader input, Writer output, char[] buffer) throws IOException
Reader to a Writer.
This method uses the provided buffer, so there is no need to use a
BufferedReader.
input - the Reader to read fromoutput - the Writer to write tobuffer - the buffer to be used for the copyNullPointerException - if the input or output is nullIOException - if an I/O error occurspublic static boolean contentEquals(InputStream input1, InputStream input2) throws IOException
This method buffers the input internally using
BufferedInputStream if they are not already buffered.
input1 - the first streaminput2 - the second streamNullPointerException - if either input is nullIOException - if an I/O error occursCopyright © 2017 ZeroTurnaround. All rights reserved.