Package com.norconex.commons.lang.io

Class IOUtil

  • public final class IOUtil
extends Object
    I/O related utility methods.
    Author:
    Pascal Essiembre

    • Method Detail

      • startsWith

        public static boolean startsWith​(InputStream is,
                                 byte[] bytes)
                          throws IOException
        Whether the given input stream starts the specified bytes array or not. The input stream must support marking. If the byte array or the input stream is null, then false is returned.
        Parameters:
        is - input stream
        bytes - byte array to compare
        Returns:
        true if input stream starts with byte array
        Throws:
        IOException - if InputStream.markSupported() returns false

      • borrowBytes

        public static byte[] borrowBytes​(InputStream is,
                                 int qty)
                          throws IOException
        Gets and resets the specified number of bytes from the input stream. Must support marks.
        Parameters:
        is - input stream
        qty - number of bytes to read
        Returns:
        byte array of length matching the quantity requested
        Throws:
        IOException - if InputStream.markSupported() returns false
        Since:
        2.0.0

      • borrowCharacters

        public static char[] borrowCharacters​(Reader reader,
                                      int qty)
                               throws IOException
        Gets and resets the specified number of characters from the reader. Must support marks.
        Parameters:
        reader - reader
        qty - number of characters to read
        Returns:
        char array of length matching the quantity requested
        Throws:
        IOException - if Reader.markSupported() returns false
        Since:
        2.0.0

      • isEmpty

        public static boolean isEmpty​(Reader reader)
                       throws IOException
        Gets whether the given Reader is null or empty. Must support marks.
        Parameters:
        reader - reader
        Returns:
        true if null or empty
        Throws:
        IOException - if Reader.markSupported() returns false
        Since:
        2.0.0

      • toBufferedReader

        public static BufferedReader toBufferedReader​(Reader reader)
        Wraps the reader in a BufferedReader if not a subclass already.
        Parameters:
        reader - the reader to wrap if needed
        Returns:
        buffered reader
        Since:
        1.6.0

      • toBufferedInputStream

        public static BufferedInputStream toBufferedInputStream​(InputStream in)
        Wraps the input stream in a BufferedInputStream if not a subclass already.
        Parameters:
        in - the input stream to wrap if needed
        Returns:
        buffered input stream
        Since:
        1.6.0

      • tail

        public static String[] tail​(InputStream is,
                            int lineQty)
                     throws IOException
        Gets the last lines from an input stream, using UTF-8. This method is null-safe. If the input stream is null or empty, an empty string array will be returned.

        Use of this method can often be a bad idea (especially on large streams) since it needs to read the entire stream to return the last lines. If you are dealing with files, use FileUtil.tail( java.io.File, int) instead, which can read a file starting from the end.
        Parameters:
        is - input stream
        lineQty - maximum number of lines to return
        Returns:
        lines as a string array
        Throws:
        IOException - problem reading lines

      • tail

        public static String[] tail​(InputStream is,
                            String encoding,
                            int lineQty)
                     throws IOException
        Gets the last lines from an input stream, using the specified encoding. This method is null-safe. If the input stream is null or empty, an empty string array will be returned.

        Use of this method can often be a bad idea (especially on large streams) since it needs to read the entire stream to return the last lines. If you are dealing with files, use FileUtil.tail( File, String, int) instead, which can read a file starting from the end.
        Parameters:
        is - input stream
        encoding - character encoding
        lineQty - maximum number of lines to return
        Returns:
        lines as a string array
        Throws:
        IOException - problem reading lines
        Since:
        1.5.0

      • tail

        public static String[] tail​(InputStream is,
                            Charset encoding,
                            int lineQty)
                     throws IOException
        Gets the last lines from an input stream, using the specified encoding. This method is null-safe. If the input stream is null or empty, an empty string array will be returned.

        Use of this method can often be a bad idea (especially on large streams) since it needs to read the entire stream to return the last lines. If you are dealing with files, use FileUtil.tail( File, String, int) instead, which can read a file starting from the end.
        Parameters:
        is - input stream
        encoding - character encoding
        lineQty - maximum number of lines to return
        Returns:
        lines as a string array
        Throws:
        IOException - problem reading lines
        Since:
        1.14.0

      • head

        public static String[] head​(InputStream is,
                            int lineQty)
                     throws IOException
        Gets the first lines from an input stream, using UTF-8. This method is null-safe. If the input stream is null or empty, an empty string array will be returned.
        Parameters:
        is - input stream
        lineQty - maximum number of lines to return
        Returns:
        lines as a string array
        Throws:
        IOException - problem reading lines

      • head

        public static String[] head​(InputStream is,
                            String encoding,
                            int lineQty)
                     throws IOException
        Gets the first lines from an input stream, using the specified encoding. This method is null-safe. If the input stream is null or empty, an empty string array will be returned.
        Parameters:
        is - input stream
        encoding - character encoding
        lineQty - maximum number of lines to return
        Returns:
        lines as a string array
        Throws:
        IOException - problem reading lines

      • head

        public static String[] head​(InputStream is,
                            Charset encoding,
                            int lineQty)
                     throws IOException
        Gets the first lines from an input stream, using the specified encoding. This method is null-safe. If the input stream is null or empty, an empty string array will be returned.
        Parameters:
        is - input stream
        encoding - character encoding
        lineQty - maximum number of lines to return
        Returns:
        lines as a string array
        Throws:
        IOException - problem reading lines
        Since:
        1.14.0

      • toNonNullReader

        public static Reader toNonNullReader​(Reader reader)
        Gets an "empty" reader (zero size) when the supplied reader is null. Else, return the supplied reader.
        Parameters:
        reader - original reader
        Returns:
        the supplied reader, or an empty reader
        Since:
        2.0.0

      • toNonNullInputStream

        public static InputStream toNonNullInputStream​(InputStream is)
        Gets an "empty" input stream (zero size) when the supplied input stream is null. Else, return the supplied input stream.
        Parameters:
        is - original input stream
        Returns:
        the supplied input stream, or an empty input stream
        Since:
        2.0.0

      • consume

        public static int consume​(InputStream is)
                   throws IOException
        Fully consumes an input stream.
        Parameters:
        is - input stream
        Returns:
        number of bytes consumed
        Throws:
        IOException - could not consume stream
        Since:
        2.0.0

      • consume

        public static int consume​(Reader reader)
                   throws IOException
        Fully consumes an input stream.
        Parameters:
        reader - reader
        Returns:
        number of characters consumed
        Throws:
        IOException - could not consume reader
        Since:
        2.0.0

      • consumeUntil

        public static int consumeUntil​(Reader reader,
                               IntPredicate predicate)
                        throws IOException
        Consumes markable reader characters until the predicate returns true for a character or the end of stream is reached. The character ending the consumption is not consumed (i.e., the reader cursor is reset just before that character).
        Parameters:
        reader - the reader to consume
        predicate - the character evaluation condition
        Returns:
        number of characters consumed (0 if reader is null)
        Throws:
        IOException - could not consume stream
        IllegalArgumentException - if reader does not support mark
        Since:
        2.0.0

      • consumeUntil

        public static int consumeUntil​(Reader reader,
                               IntPredicate predicate,
                               Appendable appendable)
                        throws IOException
        Consumes markable reader characters until the predicate returns true for a character or the end of stream is reached. Optionally append the consumed characters to an Appendable (e.g. StringBuilder). The character ending the consumption is not consumed (i.e., the reader cursor is reset just before that character).
        Parameters:
        reader - the reader to consume
        predicate - the character evaluation condition
        appendable - optional, to append consumed characters
        Returns:
        number of characters consumed (0 if reader is null)
        Throws:
        IOException - could not consume stream
        IllegalArgumentException - if reader does not support mark
        Since:
        2.0.0

      • consumeUntil

        public static int consumeUntil​(Reader reader,
                               String str,
                               Appendable appendable)
                        throws IOException
        Consumes reader characters until after encountering the supplied string (the matching string is also consumed) or the end of stream is reached. Optionally append the consumed characters to an Appendable (e.g. StringBuilder). The matching string is also consumed.
        Parameters:
        reader - the reader to consume
        str - the string to match
        appendable - optional, to append consumed characters
        Returns:
        number of characters consumed (0 if reader is null)
        Throws:
        IOException - could not consume stream
        Since:
        2.0.0

      • consumeWhile

        public static int consumeWhile​(Reader reader,
                               IntPredicate predicate)
                        throws IOException
        Consumes markable reader characters while the predicate returns true for a character or the end of stream is reached. The character ending the consumption is not consumed (i.e., the reader cursor is reset just before that character).
        Parameters:
        reader - the reader to consume
        predicate - the character evaluation condition
        Returns:
        number of characters consumed (0 if reader is null)
        Throws:
        IOException - could not consume stream
        IllegalArgumentException - if reader does not support mark
        Since:
        2.0.0

      • consumeWhile

        public static int consumeWhile​(Reader reader,
                               IntPredicate predicate,
                               Appendable appendable)
                        throws IOException
        Consumes markable reader characters while the predicate returns true for a character or the end of stream is reached. Optionally append the consumed characters to an Appendable (e.g. StringBuilder). The character ending the consumption is not consumed (i.e., the reader cursor is reset just before that character).
        Parameters:
        reader - the reader to consume
        predicate - the character evaluation condition
        appendable - optional, to append consumed characters
        Returns:
        number of characters consumed (0 if reader is null)
        Throws:
        IOException - could not consume stream
        IllegalArgumentException - if reader does not support mark
        Since:
        2.0.0

      • closeQuietly

        public static void closeQuietly​(Closeable... closeable)
        Given Apache has deprecated its IOUtils#closeQuietly(java.io.Closeable) method, this one offers an alternate one.
        Parameters:
        closeable - one or more input streams to close quietly
        Since:
        2.0.0