org.springframework.util

Class StreamUtils

java.lang.Object

org.springframework.util.StreamUtils

public abstract class StreamUtils
extends Object

Simple utility methods for dealing with streams. The copy methods of this class are similar to those defined in FileCopyUtils except that all affected streams are left open when done. All copy methods use a block size of 4096 bytes.

Mainly for use within the framework, but also useful for application code.

Since:

3.2.2

Author:

Juergen Hoeller, Phillip Webb, Brian Clozel

See Also:

FileCopyUtils

Field Summary

Fields

Modifier and Type	Field and Description
static int	BUFFER_SIZE The default buffer size used when copying bytes.

Constructor Summary

Constructors

Constructor and Description
StreamUtils()

Method Summary

Modifier and Type	Method and Description
static void	copy(byte[] in, OutputStream out) Copy the contents of the given byte array to the given OutputStream.
static int	copy(InputStream in, OutputStream out) Copy the contents of the given InputStream to the given OutputStream.
static void	copy(String in, Charset charset, OutputStream out) Copy the contents of the given String to the given output OutputStream.
static long	copyRange(InputStream in, OutputStream out, long start, long end) Copy a range of content of the given InputStream to the given OutputStream.
static byte[]	copyToByteArray(InputStream in) Copy the contents of the given InputStream into a new byte array.
static String	copyToString(ByteArrayOutputStream baos, Charset charset) Copy the contents of the given ByteArrayOutputStream into a String.
static String	copyToString(InputStream in, Charset charset) Copy the contents of the given InputStream into a String.
static int	drain(InputStream in) Drain the remaining content of the given InputStream.
static InputStream	emptyInput() Return an efficient empty InputStream.
static InputStream	nonClosing(InputStream in) Return a variant of the given InputStream where calling close() has no effect.
static OutputStream	nonClosing(OutputStream out) Return a variant of the given OutputStream where calling close() has no effect.

Methods inherited from class java.lang.Object

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

Field Detail

BUFFER_SIZE

public static final int BUFFER_SIZE

The default buffer size used when copying bytes.

See Also:

Constant Field Values

Constructor Detail

StreamUtils

public StreamUtils()

Method Detail

copyToByteArray

public static byte[] copyToByteArray(@Nullable
                                     InputStream in)
                              throws IOException

Copy the contents of the given InputStream into a new byte array.

Leaves the stream open when done.

Parameters:

in - the stream to copy from (may be null or empty)

Returns:

the new byte array that has been copied to (possibly empty)

Throws:

IOException - in case of I/O errors

copyToString

public static String copyToString(@Nullable
                                  InputStream in,
                                  Charset charset)
                           throws IOException

Copy the contents of the given InputStream into a String.

Leaves the stream open when done.

Parameters:

in - the InputStream to copy from (may be null or empty)

charset - the Charset to use to decode the bytes

Returns:

the String that has been copied to (possibly empty)

Throws:

IOException - in case of I/O errors

copyToString

public static String copyToString(ByteArrayOutputStream baos,
                                  Charset charset)

Copy the contents of the given ByteArrayOutputStream into a String.

This is a more effective equivalent of new String(baos.toByteArray(), charset).

As long as the charset is already available at the point of invocation, no exception is expected to be thrown by this method.

Parameters:

baos - the ByteArrayOutputStream to be copied into a String

charset - the Charset to use to decode the bytes

Returns:

the String that has been copied to (possibly empty)

Since:

5.2.6

copy

public static void copy(byte[] in,
                        OutputStream out)
                 throws IOException

Copy the contents of the given byte array to the given OutputStream.

Leaves the stream open when done.

Parameters:

in - the byte array to copy from

out - the OutputStream to copy to

Throws:

IOException - in case of I/O errors

copy

public static void copy(String in,
                        Charset charset,
                        OutputStream out)
                 throws IOException

Copy the contents of the given String to the given output OutputStream.

Leaves the stream open when done.

Parameters:

in - the String to copy from

charset - the Charset

out - the OutputStream to copy to

Throws:

IOException - in case of I/O errors

copy

public static int copy(InputStream in,
                       OutputStream out)
                throws IOException

Copy the contents of the given InputStream to the given OutputStream.

Leaves both streams open when done.

Parameters:

in - the InputStream to copy from

out - the OutputStream to copy to

Returns:

the number of bytes copied

Throws:

IOException - in case of I/O errors

copyRange

public static long copyRange(InputStream in,
                             OutputStream out,
                             long start,
                             long end)
                      throws IOException

Copy a range of content of the given InputStream to the given OutputStream.

If the specified range exceeds the length of the InputStream, this copies up to the end of the stream and returns the actual number of copied bytes.

Leaves both streams open when done.

Parameters:

in - the InputStream to copy from

out - the OutputStream to copy to

start - the position to start copying from

end - the position to end copying

Returns:

the number of bytes copied

Throws:

IOException - in case of I/O errors

Since:

4.3

drain

public static int drain(InputStream in)
                 throws IOException

Drain the remaining content of the given InputStream.

Leaves the InputStream open when done.

Parameters:

in - the InputStream to drain

Returns:

the number of bytes read

Throws:

IOException - in case of I/O errors

Since:

4.3

emptyInput

public static InputStream emptyInput()

Return an efficient empty InputStream.

Returns:

a ByteArrayInputStream based on an empty byte array

Since:

4.2.2

nonClosing

public static InputStream nonClosing(InputStream in)

Return a variant of the given InputStream where calling close() has no effect.

Parameters:

in - the InputStream to decorate

Returns:

a version of the InputStream that ignores calls to close

nonClosing

public static OutputStream nonClosing(OutputStream out)

Return a variant of the given OutputStream where calling close() has no effect.

Parameters:

out - the OutputStream to decorate

Returns:

a version of the OutputStream that ignores calls to close