java.lang.Object
- org.codehaus.plexus.util.IOUtil

```
public final class IOUtil
extends Object
```
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).

Since:

4.0

Version:

$Id$

Author:

Peter Donald, Jeff Turner

Field Summary

Fields
Modifier and Type Field Description

private static int DEFAULT_BUFFER_SIZE

Constructor Summary

Constructors
Modifier Constructor Description

private IOUtil()
Private constructor to prevent instantiation.

Method Summary

Modifier and Type	Method	Description
`static void`	`bufferedCopy(InputStream input, OutputStream output)`	Deprecated. Buffering streams is actively harmful!
`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 void`	`close(Channel channel)`	Closes a channel.
`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, OutputStream output, int bufferSize)`	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

- Field Detail
  - DEFAULT_BUFFER_SIZE
```
private static final int DEFAULT_BUFFER_SIZE
```
    See Also:
    
    Constant Field Values
- Constructor Detail
  - IOUtil
```
private IOUtil()
```
    Private constructor to prevent instantiation.
- Method Detail
  - copy
```
public static void copy(InputStream input,
                        OutputStream output)
                 throws IOException
```
    Copy bytes from an InputStream to an OutputStream.
    
    Throws:
    
    IOException
  - copy
```
public static void copy(InputStream input,
                        OutputStream output,
                        int bufferSize)
                 throws IOException
```
    Copy bytes from an InputStream to an OutputStream.
    
    Parameters:
    
    bufferSize - Size of internal buffer to use.
    
    Throws:
    
    IOException
  - copy
```
public static void copy(Reader input,
                        Writer output)
                 throws IOException
```
    Copy chars from a Reader to a Writer.
    
    Throws:
    
    IOException
  - copy
```
public static void copy(Reader input,
                        Writer output,
                        int bufferSize)
                 throws IOException
```
    Copy chars from a Reader to a Writer.
    
    Parameters:
    
    bufferSize - Size of internal buffer to use.
    
    Throws:
    
    IOException
  - copy
```
public static void copy(InputStream input,
                        Writer output)
                 throws IOException
```
    Copy and convert bytes from an InputStream to chars on a Writer. The platform's default encoding is used for the byte-to-char conversion.
    
    Throws:
    
    IOException
  - copy
```
public static void copy(InputStream input,
                        Writer output,
                        int bufferSize)
                 throws IOException
```
    Copy and convert bytes from an InputStream to chars on a Writer. The platform's default encoding is used for the byte-to-char conversion.
    
    Parameters:
    
    bufferSize - Size of internal buffer to use.
    
    Throws:
    
    IOException
  - copy
```
public static void copy(InputStream input,
                        Writer output,
                        String encoding)
                 throws IOException
```
    Copy and convert bytes from an InputStream to chars on a Writer, using the specified encoding.
    
    Parameters:
    
    encoding - The name of a supported character encoding. See the IANA Charset Registry for a list of valid encoding types.
    
    Throws:
    
    IOException
  - copy
```
public static void copy(InputStream input,
                        Writer output,
                        String encoding,
                        int bufferSize)
                 throws IOException
```
    Copy and convert bytes from an InputStream to chars on a Writer, using the specified encoding.
    
    Parameters:
    
    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.
    
    Throws:
    
    IOException
  - toString
```
public static String toString(InputStream input)
                       throws IOException
```
    Get the contents of an InputStream as a String. The platform's default encoding is used for the byte-to-char conversion.
    
    Throws:
    
    IOException
  - toString
```
public static String toString(InputStream input,
                              int bufferSize)
                       throws IOException
```
    Get the contents of an InputStream as a String. The platform's default encoding is used for the byte-to-char conversion.
    
    Parameters:
    
    bufferSize - Size of internal buffer to use.
    
    Throws:
    
    IOException
  - toString
```
public static String toString(InputStream input,
                              String encoding)
                       throws IOException
```
    Get the contents of an InputStream as a String.
    
    Parameters:
    
    encoding - The name of a supported character encoding. See the IANA Charset Registry for a list of valid encoding types.
    
    Throws:
    
    IOException
  - toString
```
public static String toString(InputStream input,
                              String encoding,
                              int bufferSize)
                       throws IOException
```
    Get the contents of an InputStream as a String.
    
    Parameters:
    
    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.
    
    Throws:
    
    IOException
  - toByteArray
```
public static byte[] toByteArray(InputStream input)
                          throws IOException
```
    Get the contents of an InputStream as a byte[].
    
    Throws:
    
    IOException
  - toByteArray
```
public static byte[] toByteArray(InputStream input,
                                 int bufferSize)
                          throws IOException
```
    Get the contents of an InputStream as a byte[].
    
    Parameters:
    
    bufferSize - Size of internal buffer to use.
    
    Throws:
    
    IOException
  - copy
```
public static void copy(Reader input,
                        OutputStream output)
                 throws IOException
```
    Serialize chars from a Reader to bytes on an OutputStream, and flush the OutputStream.
    
    Throws:
    
    IOException
  - copy
```
public static void copy(Reader input,
                        OutputStream output,
                        int bufferSize)
                 throws IOException
```
    Serialize chars from a Reader to bytes on an OutputStream, and flush the OutputStream.
    
    Parameters:
    
    bufferSize - Size of internal buffer to use.
    
    Throws:
    
    IOException
  - toString
```
public static String toString(Reader input)
                       throws IOException
```
    Get the contents of a Reader as a String.
    
    Throws:
    
    IOException
  - toString
```
public static String toString(Reader input,
                              int bufferSize)
                       throws IOException
```
    Get the contents of a Reader as a String.
    
    Parameters:
    
    bufferSize - Size of internal buffer to use.
    
    Throws:
    
    IOException
  - toByteArray
```
public static byte[] toByteArray(Reader input)
                          throws IOException
```
    Get the contents of a Reader as a byte[].
    
    Throws:
    
    IOException
  - toByteArray
```
public static byte[] toByteArray(Reader input,
                                 int bufferSize)
                          throws IOException
```
    Get the contents of a Reader as a byte[].
    
    Parameters:
    
    bufferSize - Size of internal buffer to use.
    
    Throws:
    
    IOException
  - copy
```
public static void copy(String input,
                        OutputStream output)
                 throws IOException
```
    Serialize chars from a String to bytes on an OutputStream, and flush the OutputStream.
    
    Throws:
    
    IOException
  - copy
```
public static void copy(String input,
                        OutputStream output,
                        int bufferSize)
                 throws IOException
```
    Serialize chars from a String to bytes on an OutputStream, and flush the OutputStream.
    
    Parameters:
    
    bufferSize - Size of internal buffer to use.
    
    Throws:
    
    IOException
  - copy
```
public static void copy(String input,
                        Writer output)
                 throws IOException
```
    Copy chars from a String to a Writer.
    
    Throws:
    
    IOException
  - bufferedCopy
```
public static void bufferedCopy(InputStream input,
                                OutputStream output)
                         throws IOException
```
    Deprecated.
    Buffering streams is actively harmful! See the class description as to why. Use copy(InputStream, OutputStream) instead.
    
    Copy bytes from an InputStream to an OutputStream, with buffering. This is equivalent to passing a BufferedInputStream and BufferedOutputStream to copy(InputStream, OutputStream), and flushing the output stream afterwards. The streams are not closed after the copy.
    
    Throws:
    
    IOException
  - toByteArray
```
public static byte[] toByteArray(String input)
                          throws IOException
```
    Get the contents of a String as a byte[].
    
    Throws:
    
    IOException
  - toByteArray
```
public static byte[] toByteArray(String input,
                                 int bufferSize)
                          throws IOException
```
    Get the contents of a String as a byte[].
    
    Parameters:
    
    bufferSize - Size of internal buffer to use.
    
    Throws:
    
    IOException
  - copy
```
public static void copy(byte[] input,
                        Writer output)
                 throws IOException
```
    Copy and convert bytes from a byte[] to chars on a Writer. The platform's default encoding is used for the byte-to-char conversion.
    
    Throws:
    
    IOException
  - copy
```
public static void copy(byte[] input,
                        Writer output,
                        int bufferSize)
                 throws IOException
```
    Copy and convert bytes from a byte[] to chars on a Writer. The platform's default encoding is used for the byte-to-char conversion.
    
    Parameters:
    
    bufferSize - Size of internal buffer to use.
    
    Throws:
    
    IOException
  - copy
```
public static void copy(byte[] input,
                        Writer output,
                        String encoding)
                 throws IOException
```
    Copy and convert bytes from a byte[] to chars on a Writer, using the specified encoding.
    
    Parameters:
    
    encoding - The name of a supported character encoding. See the IANA Charset Registry for a list of valid encoding types.
    
    Throws:
    
    IOException
  - copy
```
public static void copy(byte[] input,
                        Writer output,
                        String encoding,
                        int bufferSize)
                 throws IOException
```
    Copy and convert bytes from a byte[] to chars on a Writer, using the specified encoding.
    
    Parameters:
    
    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.
    
    Throws:
    
    IOException
  - toString
```
public static String toString(byte[] input)
                       throws IOException
```
    Get the contents of a byte[] as a String. The platform's default encoding is used for the byte-to-char conversion.
    
    Throws:
    
    IOException
  - toString
```
public static String toString(byte[] input,
                              int bufferSize)
                       throws IOException
```
    Get the contents of a byte[] as a String. The platform's default encoding is used for the byte-to-char conversion.
    
    Parameters:
    
    bufferSize - Size of internal buffer to use.
    
    Throws:
    
    IOException
  - toString
```
public static String toString(byte[] input,
                              String encoding)
                       throws IOException
```
    Get the contents of a byte[] as a String.
    
    Parameters:
    
    encoding - The name of a supported character encoding. See the IANA Charset Registry for a list of valid encoding types.
    
    Throws:
    
    IOException
  - toString
```
public static String toString(byte[] input,
                              String encoding,
                              int bufferSize)
                       throws IOException
```
    Get the contents of a byte[] as a String.
    
    Parameters:
    
    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.
    
    Throws:
    
    IOException
  - copy
```
public static void copy(byte[] input,
                        OutputStream output)
                 throws IOException
```
    Copy bytes from a byte[] to an OutputStream.
    
    Throws:
    
    IOException
  - copy
```
public static void copy(byte[] input,
                        OutputStream output,
                        int bufferSize)
                 throws IOException
```
    Copy bytes from a byte[] to an OutputStream.
    
    Parameters:
    
    bufferSize - Size of internal buffer to use.
    
    Throws:
    
    IOException
  - contentEquals
```
public static boolean contentEquals(InputStream input1,
                                    InputStream input2)
                             throws IOException
```
    Compare the contents of two Streams to determine if they are equal or not.
    
    Parameters:
    
    input1 - the first stream
    
    input2 - the second stream
    
    Returns:
    
    true if the content of the streams are equal or they both don't exist, false otherwise
    
    Throws:
    
    IOException
  - close
```
public static void close(InputStream inputStream)
```
    Closes the input stream. The input stream can be null and any IOException's will be swallowed.
    
    Parameters:
    
    inputStream - The stream to close.
  - close
```
public static void close(Channel channel)
```
    Closes a channel. Channel can be null and any IOException's will be swallowed.
    
    Parameters:
    
    channel - The stream to close.
  - close
```
public static void close(OutputStream outputStream)
```
    Closes the output stream. The output stream can be null and any IOException's will be swallowed.
    
    Parameters:
    
    outputStream - The stream to close.
  - close
```
public static void close(Reader reader)
```
    Closes the reader. The reader can be null and any IOException's will be swallowed.
    
    Parameters:
    
    reader - The reader to close.
  - close
```
public static void close(Writer writer)
```
    Closes the writer. The writer can be null and any IOException's will be swallowed.
    
    Parameters:
    
    writer - The writer to close.

Class IOUtil

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

DEFAULT_BUFFER_SIZE

Constructor Detail

IOUtil

Method Detail

copy

copy

copy

copy

copy

copy

copy

copy

toString

toString

toString

toString

toByteArray

toByteArray

copy

copy

toString

toString

toByteArray

toByteArray

copy

copy

copy

bufferedCopy

toByteArray

toByteArray

copy

copy

copy

copy

toString

toString

toString

toString

copy

copy

contentEquals

close

close

close

close

close