org.apache.maven.shared.utils.io.IOUtil
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java.lang.Object
public final class IOUtil
General IO Stream manipulation.
This class provides static utility methods for input/output operations, particularly buffered
copying between sources (InputStream, Reader, String and
byte[]) and destinations (OutputStream, Writer,
String and byte[]).
Unless otherwise noted, these copy methods do not flush or close the
streams. Often, doing so would require making non-portable assumptions about the streams' origin
and further use. This means that both streams' close() methods must be called after
copying. if one omits this step, then the stream resources (sockets, file descriptors) are
released when the associated Stream is garbage-collected. It is not a good idea to rely on this
mechanism. For a good overview of the distinction between "memory management" and "resource
management", see this
UnixReview article
For each copy method, a variant is provided that allows the caller to specify the
buffer size (the default is 4k). As the buffer size can have a fairly large impact on speed, this
may be worth tweaking. Often "large buffer -> faster" does not hold, even for large data
transfers.
For byte-to-char methods, a copy variant allows the encoding to be selected
(otherwise the platform default is used).
The copy methods use an internal buffer when copying. It is therefore advisable
not to deliberately wrap the stream arguments to the copy methods in
Buffered* streams. For example, don't do the
following:
copy( new BufferedInputStream( in ), new BufferedOutputStream( out ) );
The rationale is as follows:
Imagine that an InputStream's read() is a very expensive operation, which would usually suggest
wrapping in a BufferedInputStream. The BufferedInputStream works by issuing infrequent
InputStream.read(byte[] b, int off, int len) requests on the underlying InputStream, to
fill an internal buffer, from which further read requests can inexpensively get
their data (until the buffer runs out).
However, the copy methods do the same thing, keeping an internal buffer,
populated by InputStream.read(byte[] b, int off, int len) requests. Having two buffers
(or three if the destination stream is also buffered) is pointless, and the unnecessary buffer
management hurts performance slightly (about 3%, according to some simple experiments).
| Method Summary | |
|---|---|
static void |
close(Channel channel)
Closes a channel. |
static void |
close(InputStream inputStream)
Closes the input stream. |
static void |
close(OutputStream outputStream)
Closes the output stream. |
static void |
close(Reader reader)
Closes the reader. |
static void |
close(Writer writer)
Closes the writer. |
static boolean |
contentEquals(InputStream input1,
InputStream input2)
Compare the contents of two Streams to determine if they are equal or not. |
static void |
copy(byte[] input,
OutputStream output)
Copy bytes from a byte[] to an OutputStream. |
static void |
copy(byte[] input,
Writer output)
Copy and convert bytes from a byte[] to chars on a
Writer. |
static void |
copy(byte[] input,
Writer output,
int bufferSize)
Copy and convert bytes from a byte[] to chars on a
Writer. |
static void |
copy(byte[] input,
Writer output,
String encoding)
Copy and convert bytes from a byte[] to chars on a
Writer, using the specified encoding. |
static void |
copy(byte[] input,
Writer output,
String encoding,
int bufferSize)
Copy and convert bytes from a byte[] to chars on a
Writer, using the specified encoding. |
static void |
copy(InputStream input,
OutputStream output)
Copy bytes from an InputStream to an OutputStream. |
static void |
copy(InputStream input,
OutputStream output,
int bufferSize)
Copy bytes from an InputStream to an OutputStream. |
static void |
copy(InputStream input,
Writer output)
Copy and convert bytes from an InputStream to chars on a
Writer. |
static void |
copy(InputStream input,
Writer output,
int bufferSize)
Copy and convert bytes from an InputStream to chars on a
Writer. |
static void |
copy(InputStream input,
Writer output,
String encoding)
Copy and convert bytes from an InputStream to chars on a
Writer, using the specified encoding. |
static void |
copy(InputStream input,
Writer output,
String encoding,
int bufferSize)
Copy and convert bytes from an InputStream to chars on a
Writer, using the specified encoding. |
static void |
copy(Reader input,
OutputStream output)
Serialize chars from a Reader to bytes on an OutputStream, and
flush the OutputStream. |
static void |
copy(Reader input,
OutputStream output,
int bufferSize)
Serialize chars from a Reader to bytes on an OutputStream, and
flush the OutputStream. |
static void |
copy(Reader input,
Writer output)
Copy chars from a Reader to a Writer. |
static void |
copy(Reader input,
Writer output,
int bufferSize)
Copy chars from a Reader to a Writer. |
static void |
copy(String input,
OutputStream output)
Serialize chars from a String to bytes on an OutputStream, and
flush the OutputStream. |
static void |
copy(String input,
OutputStream output,
int bufferSize)
Serialize chars from a String to bytes on an OutputStream, and
flush the OutputStream. |
static void |
copy(String input,
Writer output)
Copy chars from a String to a Writer. |
static byte[] |
toByteArray(InputStream input)
Get the contents of an InputStream as a byte[]. |
static byte[] |
toByteArray(InputStream input,
int bufferSize)
Get the contents of an InputStream as a byte[]. |
static byte[] |
toByteArray(Reader input)
Get the contents of a Reader as a byte[]. |
static byte[] |
toByteArray(Reader input,
int bufferSize)
Get the contents of a Reader as a byte[]. |
static byte[] |
toByteArray(String input)
Get the contents of a String as a byte[]. |
static byte[] |
toByteArray(String input,
int bufferSize)
Get the contents of a String as a byte[]. |
static String |
toString(byte[] input)
Get the contents of a byte[] as a String. |
static String |
toString(byte[] input,
int bufferSize)
Get the contents of a byte[] as a String. |
static String |
toString(byte[] input,
String encoding)
Get the contents of a byte[] as a String. |
static String |
toString(byte[] input,
String encoding,
int bufferSize)
Get the contents of a byte[] as a String. |
static String |
toString(InputStream input)
Get the contents of an InputStream as a String. |
static String |
toString(InputStream input,
int bufferSize)
Get the contents of an InputStream as a String. |
static String |
toString(InputStream input,
String encoding)
Get the contents of an InputStream as a String. |
static String |
toString(InputStream input,
String encoding,
int bufferSize)
Get the contents of an InputStream as a String. |
static String |
toString(Reader input)
Get the contents of a Reader as a String. |
static String |
toString(Reader input,
int bufferSize)
Get the contents of a Reader as a String. |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Method Detail |
|---|
public static void copy(@Nonnull
InputStream input,
@Nonnull
OutputStream output)
throws IOException
InputStream to an OutputStream.
IOException
public static void copy(@Nonnull
InputStream input,
@Nonnull
OutputStream output,
int bufferSize)
throws IOException
InputStream to an OutputStream.
bufferSize - Size of internal buffer to use.
IOException
public static void copy(@Nonnull
Reader input,
@Nonnull
Writer output)
throws IOException
Reader to a Writer.
IOException
public static void copy(@Nonnull
Reader input,
@Nonnull
Writer output,
int bufferSize)
throws IOException
Reader to a Writer.
bufferSize - Size of internal buffer to use.
IOException
public static void copy(@Nonnull
InputStream input,
@Nonnull
Writer output)
throws IOException
InputStream to chars on a
Writer.
The platform's default encoding is used for the byte-to-char conversion.
IOException
public static void copy(@Nonnull
InputStream input,
@Nonnull
Writer output,
int bufferSize)
throws IOException
InputStream to chars on a
Writer.
The platform's default encoding is used for the byte-to-char conversion.
bufferSize - Size of internal buffer to use.
IOException
public static void copy(@Nonnull
InputStream input,
@Nonnull
Writer output,
@Nonnull
String encoding)
throws IOException
InputStream to chars on a
Writer, using the specified encoding.
encoding - The name of a supported character encoding. See the
IANA
Charset Registry for a list of valid encoding types.
IOException
public static void copy(@Nonnull
InputStream input,
@Nonnull
Writer output,
@Nonnull
String encoding,
int bufferSize)
throws IOException
InputStream to chars on a
Writer, using the specified encoding.
encoding - The name of a supported character encoding. See the
IANA
Charset Registry for a list of valid encoding types.bufferSize - Size of internal buffer to use.
IOException
@Nonnull
public static String toString(@Nonnull
InputStream input)
throws IOException
InputStream as a String.
The platform's default encoding is used for the byte-to-char conversion.
IOException
@Nonnull
public static String toString(@Nonnull
InputStream input,
int bufferSize)
throws IOException
InputStream as a String.
The platform's default encoding is used for the byte-to-char conversion.
bufferSize - Size of internal buffer to use.
IOException
@Nonnull
public static String toString(@Nonnull
InputStream input,
@Nonnull
String encoding)
throws IOException
InputStream as a String.
encoding - The name of a supported character encoding. See the
IANA
Charset Registry for a list of valid encoding types.
IOException
@Nonnull
public static String toString(@Nonnull
InputStream input,
@Nonnull
String encoding,
int bufferSize)
throws IOException
InputStream as a String.
encoding - The name of a supported character encoding. See the
IANA
Charset Registry for a list of valid encoding types.bufferSize - Size of internal buffer to use.
IOException
@Nonnull
public static byte[] toByteArray(@Nonnull
InputStream input)
throws IOException
InputStream as a byte[].
IOException
@Nonnull
public static byte[] toByteArray(@Nonnull
InputStream input,
int bufferSize)
throws IOException
InputStream as a byte[].
bufferSize - Size of internal buffer to use.
IOException
public static void copy(@Nonnull
Reader input,
@Nonnull
OutputStream output)
throws IOException
Reader to bytes on an OutputStream, and
flush the OutputStream.
IOException
public static void copy(@Nonnull
Reader input,
@Nonnull
OutputStream output,
int bufferSize)
throws IOException
Reader to bytes on an OutputStream, and
flush the OutputStream.
bufferSize - Size of internal buffer to use.
IOException
@Nonnull
public static String toString(@Nonnull
Reader input)
throws IOException
Reader as a String.
IOException
@Nonnull
public static String toString(@Nonnull
Reader input,
int bufferSize)
throws IOException
Reader as a String.
bufferSize - Size of internal buffer to use.
IOException
@Nonnull
public static byte[] toByteArray(@Nonnull
Reader input)
throws IOException
Reader as a byte[].
IOException
@Nonnull
public static byte[] toByteArray(@Nonnull
Reader input,
int bufferSize)
throws IOException
Reader as a byte[].
bufferSize - Size of internal buffer to use.
IOException
public static void copy(@Nonnull
String input,
@Nonnull
OutputStream output)
throws IOException
String to bytes on an OutputStream, and
flush the OutputStream.
IOException
public static void copy(@Nonnull
String input,
@Nonnull
OutputStream output,
int bufferSize)
throws IOException
String to bytes on an OutputStream, and
flush the OutputStream.
bufferSize - Size of internal buffer to use.
IOException
public static void copy(@Nonnull
String input,
@Nonnull
Writer output)
throws IOException
String to a Writer.
IOException
@Nonnull
public static byte[] toByteArray(@Nonnull
String input)
throws IOException
String as a byte[].
IOException
@Nonnull
public static byte[] toByteArray(@Nonnull
String input,
int bufferSize)
throws IOException
String as a byte[].
bufferSize - Size of internal buffer to use.
IOException
public static void copy(@Nonnull
byte[] input,
@Nonnull
Writer output)
throws IOException
byte[] to chars on a
Writer.
The platform's default encoding is used for the byte-to-char conversion.
IOException
public static void copy(@Nonnull
byte[] input,
@Nonnull
Writer output,
int bufferSize)
throws IOException
byte[] to chars on a
Writer.
The platform's default encoding is used for the byte-to-char conversion.
bufferSize - Size of internal buffer to use.
IOException
public static void copy(@Nonnull
byte[] input,
@Nonnull
Writer output,
String encoding)
throws IOException
byte[] to chars on a
Writer, using the specified encoding.
encoding - The name of a supported character encoding. See the
IANA
Charset Registry for a list of valid encoding types.
IOException
public static void copy(@Nonnull
byte[] input,
@Nonnull
Writer output,
@Nonnull
String encoding,
int bufferSize)
throws IOException
byte[] to chars on a
Writer, using the specified encoding.
encoding - The name of a supported character encoding. See the
IANA
Charset Registry for a list of valid encoding types.bufferSize - Size of internal buffer to use.
IOException
@Nonnull
public static String toString(@Nonnull
byte[] input)
throws IOException
byte[] as a String.
The platform's default encoding is used for the byte-to-char conversion.
IOException
@Nonnull
public static String toString(@Nonnull
byte[] input,
int bufferSize)
throws IOException
byte[] as a String.
The platform's default encoding is used for the byte-to-char conversion.
bufferSize - Size of internal buffer to use.
IOException
@Nonnull
public static String toString(@Nonnull
byte[] input,
@Nonnull
String encoding)
throws IOException
byte[] as a String.
encoding - The name of a supported character encoding. See the
IANA
Charset Registry for a list of valid encoding types.
IOException
@Nonnull
public static String toString(@Nonnull
byte[] input,
@Nonnull
String encoding,
int bufferSize)
throws IOException
byte[] as a String.
encoding - The name of a supported character encoding. See the
IANA
Charset Registry for a list of valid encoding types.bufferSize - Size of internal buffer to use.
IOException
public static void copy(@Nonnull
byte[] input,
@Nonnull
OutputStream output)
throws IOException
byte[] to an OutputStream.
IOException
public static boolean contentEquals(@Nonnull
InputStream input1,
@Nonnull
InputStream input2)
throws IOException
input1 - the first streaminput2 - the second stream
IOException
public static void close(@Nullable
Channel channel)
channel - The stream to close.
public static void close(@Nullable
InputStream inputStream)
inputStream - The stream to close.
public static void close(@Nullable
OutputStream outputStream)
outputStream - The stream to close.
public static void close(@Nullable
Reader reader)
reader - The reader to close.
public static void close(@Nullable
Writer writer)
writer - The writer to close.
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