Package org.eclipse.rdf4j.common.io

Class IOUtil

java.lang.Object

org.eclipse.rdf4j.common.io.IOUtil

public class IOUtil
extends Object

Utility methods for I/O working with Readers, Writers, InputStreams and OutputStreams.

Constructor Summary

Constructors

Constructor	Description
IOUtil()

Method Summary

Modifier and Type	Method	Description
static void	main(String[] args)
static byte[]	readBytes(File file)	Reads all bytes from the specified file and returns them as a byte array.
static byte[]	readBytes(InputStream in)	Reads all bytes from the supplied input stream and returns them as a byte array.
static int	readBytes(InputStream in, byte[] byteArray)	Fills the supplied byte array with bytes read from the specified InputStream.
static byte[]	readBytes(InputStream in, int maxBytes)	Reads at most maxBytes bytes from the supplied input stream and returns them as a byte array.
static char[]	readChars(Reader r)	Reads all characters from the supplied reader and returns them.
static int	readChars(Reader r, char[] charArray)	Fills the supplied character array with characters read from the specified Reader.
static char[]	readChars(URL url)	Read the contents of a (unbuffered) resource into a character array.
static Properties	readProperties(File propsFile)	Read properties from the specified file.
static Properties	readProperties(File propsFile, Properties defaults)	Read properties from the specified file.
static Properties	readProperties(InputStream in)	Read properties from the specified InputStream.
static Properties	readProperties(InputStream in, Properties defaults)	Read properties from the specified InputStream.
static String	readString(File file)	Read the contents as a string from the given (unbuffered) file.
static String	readString(InputStream in)	Read the contents of an (unbuffered) input stream into a single string.
static String	readString(Reader r)	Reads all characters from the supplied reader and returns them as a string.
static String	readString(Reader r, int maxChars)	Reads a string of at most length maxChars from the supplied Reader.
static String	readString(URL url)	Read the contents of a (unbuffered) resource into one single string.
static int	readVarInt(InputStream in)	Read an variable length integer.
static final long	transfer(InputStream in, File file)	Writes all bytes from an InputStream to a file.
static final long	transfer(InputStream in, OutputStream out)	Transfers all bytes that can be read from in to out.
static final long	transfer(Reader reader, File file)	Writes all characters from a Reader to a file using the default character encoding.
static final long	transfer(Reader in, Writer out)	Transfers all characters that can be read from in to out .
static Reader	urlToReader(URL url)	Read the contents of a resource into a reader.
static void	writeBytes(byte[] data, File file)	Write the contents of a byte array (unbuffered) to a file.
static void	writeBytes(byte[] data, OutputStream out)	Write he contents of a byte array (unbuffered) to an output stream.
static void	writeProperties(Properties props, File file, boolean includeDefaults)	Write the specified properties to the specified file.
static void	writeProperties(Properties props, OutputStream out, boolean includeDefaults)	Write the specified properties to the specified output stream.
static void	writeStream(InputStream in, File file)	Writes all data that can be read from the supplied InputStream to the specified file.
static void	writeString(String contents, File file)	Write the contents of a string (unbuffered) to a file
static void	writeVarInt(OutputStream out, int value)	Write an variable length (non-negative) integer.

Methods inherited from class java.lang.Object

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

Constructor Details

IOUtil

public IOUtil()

Method Details

readString

public static String readString(File file)
                         throws IOException

Read the contents as a string from the given (unbuffered) file.

Parameters:

file - file to read

Returns:

content as one single string

Throws:

IOException

readString

public static String readString(URL url)
                         throws IOException

Read the contents of a (unbuffered) resource into one single string.

Parameters:

url - url to get the data from

Returns:

string

Throws:

IOException

readString

public static String readString(InputStream in)
                         throws IOException

Read the contents of an (unbuffered) input stream into a single string.

Parameters:

in - input stream

Returns:

string

Throws:

IOException

readString

public static String readString(Reader r)
                         throws IOException

Reads all characters from the supplied reader and returns them as a string.

Parameters:

r - The Reader supplying the characters

Returns:

A String containing all characters from the supplied reader.

Throws:

IOException

readString

public static String readString(Reader r,
 int maxChars)
                         throws IOException

Reads a string of at most length maxChars from the supplied Reader.

Parameters:

r - The Reader to read the string from.

maxChars - The maximum number of characters to read.

Returns:

A String of length maxChars, or less if the supplied Reader did not contain that much characters.

Throws:

IOException

readChars

public static char[] readChars(URL url)
                        throws IOException

Read the contents of a (unbuffered) resource into a character array.

Parameters:

url - url to get the data from

Returns:

character array

Throws:

IOException

readChars

public static char[] readChars(Reader r)
                        throws IOException

Reads all characters from the supplied reader and returns them.

Parameters:

r - The Reader supplying the characters

Returns:

A character array containing all characters from the supplied reader.

Throws:

IOException

readChars

public static int readChars(Reader r,
 char[] charArray)
                     throws IOException

Fills the supplied character array with characters read from the specified Reader. This method will only stop reading when the character array has been filled completely, or the end of the stream has been reached.

Parameters:

r - The Reader to read the characters from.

charArray - The character array to fill with characters.

Returns:

The number of characters written to the character array.

Throws:

IOException

readBytes

public static byte[] readBytes(File file)
                        throws IOException

Reads all bytes from the specified file and returns them as a byte array.

Parameters:

file - The file to read.

Returns:

A byte array containing all bytes from the specified file.

Throws:

IOException - If an I/O error occurred while reading from the file.

IllegalArgumentException - If the file size exceeds the maximum array length (larger than Integer.MAX_VALUE.

readBytes

public static byte[] readBytes(InputStream in)
                        throws IOException

Reads all bytes from the supplied input stream and returns them as a byte array.

Parameters:

in - The InputStream supplying the bytes.

Returns:

A byte array containing all bytes from the supplied input stream.

Throws:

IOException

readBytes

public static byte[] readBytes(InputStream in,
 int maxBytes)
                        throws IOException

Reads at most maxBytes bytes from the supplied input stream and returns them as a byte array.

Parameters:

in - The InputStream supplying the bytes.

maxBytes - The maximum number of bytes to read from the input stream.

Returns:

A byte array of size maxBytes if the input stream can produce that amount of bytes, or a smaller byte array containing all available bytes from the stream otherwise.

Throws:

IOException

readBytes

public static int readBytes(InputStream in,
 byte[] byteArray)
                     throws IOException

Fills the supplied byte array with bytes read from the specified InputStream. This method will only stop reading when the byte array has been filled completely, or the end of the stream has been reached.

Parameters:

in - The InputStream to read the bytes from.

byteArray - The byte array to fill with bytes.

Returns:

The number of bytes written to the byte array.

Throws:

IOException

readProperties

public static Properties readProperties(File propsFile)
                                 throws IOException

Read properties from the specified file.

Parameters:

propsFile - the file to read from

Returns:

Properties loaded from the specified file

Throws:

IOException - when the file could not be read properly

readProperties

public static Properties readProperties(File propsFile,
 Properties defaults)
                                 throws IOException

Read properties from the specified file.

Parameters:

propsFile - the file to read from

defaults - the default properties to use

Returns:

Properties loaded from the specified file

Throws:

IOException - when the file could not be read properly

readProperties

public static Properties readProperties(InputStream in)
                                 throws IOException

Read properties from the specified InputStream.

Parameters:

in - the stream to read from. The stream will be closed by this method.

Returns:

Properties loaded from the specified stream. The stream will be closed by this method.

Throws:

IOException - when the stream could not be read properly

readProperties

public static Properties readProperties(InputStream in,
 Properties defaults)
                                 throws IOException

Read properties from the specified InputStream.

Parameters:

in - the stream to read from. The stream will be closed by this method.

defaults - the default properties

Returns:

Properties loaded from the specified stream. The stream will be closed by this method.

Throws:

IOException - when the stream could not be read properly

writeProperties

public static void writeProperties(Properties props,
 File file,
 boolean includeDefaults)
                            throws IOException

Write the specified properties to the specified file.

Parameters:

props - the properties to write

file - the file to write to

includeDefaults - true when default values need to be included

Throws:

IOException - when the properties could not be written to the file properly

writeProperties

public static void writeProperties(Properties props,
 OutputStream out,
 boolean includeDefaults)
                            throws IOException

Write the specified properties to the specified output stream.

Parameters:

props - the properties to write

out - the output stream to write to

includeDefaults - true if default values need to be included

Throws:

IOException - when the properties could not be written to the output stream properly

writeStream

public static void writeStream(InputStream in,
 File file)
                        throws IOException

Writes all data that can be read from the supplied InputStream to the specified file.

Parameters:

in - An InputStream.

file - The file to write the data to.

Throws:

IOException - If an I/O error occurred.

writeString

public static void writeString(String contents,
 File file)
                        throws IOException

Write the contents of a string (unbuffered) to a file

Parameters:

contents - string contents to write

file - file to write to

Throws:

IOException

writeBytes

public static void writeBytes(byte[] data,
 File file)
                       throws IOException

Write the contents of a byte array (unbuffered) to a file.

Parameters:

data - data to write

file - file

Throws:

IOException

writeBytes

public static void writeBytes(byte[] data,
 OutputStream out)
                       throws IOException

Write he contents of a byte array (unbuffered) to an output stream.

Parameters:

data - data to write

out - file

Throws:

IOException

urlToReader

public static Reader urlToReader(URL url)
                          throws IOException

Read the contents of a resource into a reader. Currently ignores HTTP Content-Encoding response header.

Parameters:

url - url

Returns:

reader

Throws:

IOException

transfer

public static final long transfer(InputStream in,
 OutputStream out)
                           throws IOException

Transfers all bytes that can be read from in to out.

Parameters:

in - The InputStream to read data from.

out - The OutputStream to write data to.

Returns:

The total number of bytes transfered.

Throws:

IOException

transfer

public static final long transfer(InputStream in,
 File file)
                           throws IOException

Writes all bytes from an InputStream to a file.

Parameters:

in - The InputStream containing the data to write to the file.

file - The file to write the data to.

Returns:

The total number of bytes written.

Throws:

IOException - If an I/O error occurred while trying to write the data to the file.

transfer

public static final long transfer(Reader in,
 Writer out)
                           throws IOException

Transfers all characters that can be read from in to out .

Parameters:

in - The Reader to read characters from.

out - The Writer to write characters to.

Returns:

The total number of characters transfered.

Throws:

IOException

transfer

public static final long transfer(Reader reader,
 File file)
                           throws IOException

Writes all characters from a Reader to a file using the default character encoding.

Parameters:

reader - The Reader containing the data to write to the file.

file - The file to write the data to.

Returns:

The total number of characters written.

Throws:

IOException - If an I/O error occurred while trying to write the data to the file.

See Also:

• FileWriter

writeVarInt

public static void writeVarInt(OutputStream out,
 int value)
                        throws IOException

Write an variable length (non-negative) integer.

The variable length integer encoding (also know as varint and vint) writes non-negative / unsigned integers in a minimal number of bytes (binary octets). The encoding uses the most significant bit is used to indicate whether another varint byte follows. The remaining 7 bits of every octet are used to store the binary representation of the actual integer value. Note that the least significant bytes of the integer value are stored before more significate bytes.

The table below shows a few examples of decimals encoded both as a 32-bit integer and as variable length binary:

 
 decimal |           32-bit integer            |          variable length binary
       0 | 00000000 00000000 00000000 00000000 |                   00000000   (1 byte)
       1 | 00000000 00000000 00000000 00000001 |                   00000001   (1 byte)
      42 | 00000000 00000000 00000000 00101010 |                   00101010   (1 byte)
     421 | 00000000 00000000 00000001 10100101 |          10100101 00000011   (2 bytes)
  100000 | 00000000 00000001 10000110 10100000 | 10100000 10001101 00000110   (3 bytes)
 
 

Parameters:

out - The OutputStream to write to.

value - The int value to write.

Throws:

IOException - If an error occurred while writing the integer.

main

public static void main(String[] args)
                 throws IOException

Throws:

IOException

readVarInt

public static int readVarInt(InputStream in)
                      throws IOException

Read an variable length integer. See writeVarInt(OutputStream, int) for encoding details.

Parameters:

in - The InputStream to read from.

Returns:

The integer read.

Throws:

IOException - If an error occurred while reading the integer.