Package org.apache.avro.io

Class BinaryDecoder

java.lang.Object
org.apache.avro.io.Decoder
org.apache.avro.io.BinaryDecoder
public class BinaryDecoder extends Decoder
An Decoder for binary-format data.

Instances are created using DecoderFactory.

This class may read-ahead and buffer bytes from the source beyond what is required to serve its read methods. The number of unused bytes in the buffer can be accessed by inputStream().remaining(), if the BinaryDecoder is not 'direct'.

See Also:

  • Constructor Details

    • BinaryDecoder

      protected BinaryDecoder()
      protected constructor for child classes

  • Method Details

    • readNull

      public void readNull() throws IOException
      Description copied from class: Decoder
      "Reads" a null value. (Doesn't actually read anything, but advances the state of the parser if the implementation is stateful.)
      Specified by:
      readNull in class Decoder
      Throws:
      IOException

    • readBoolean

      public boolean readBoolean() throws IOException
      Description copied from class: Decoder
      Reads a boolean value written by Encoder.writeBoolean(boolean).
      Specified by:
      readBoolean in class Decoder
      Throws:
      IOException

    • readInt

      public int readInt() throws IOException
      Description copied from class: Decoder
      Reads an integer written by Encoder.writeInt(int).
      Specified by:
      readInt in class Decoder
      Throws:
      IOException

    • readLong

      public long readLong() throws IOException
      Description copied from class: Decoder
      Reads a long written by Encoder.writeLong(long).
      Specified by:
      readLong in class Decoder
      Throws:
      IOException

    • readFloat

      public float readFloat() throws IOException
      Description copied from class: Decoder
      Reads a float written by Encoder.writeFloat(float).
      Specified by:
      readFloat in class Decoder
      Throws:
      IOException

    • readDouble

      public double readDouble() throws IOException
      Description copied from class: Decoder
      Reads a double written by Encoder.writeDouble(double).
      Specified by:
      readDouble in class Decoder
      Throws:
      IOException

    • readString

      public Utf8 readString(Utf8 old) throws IOException
      Description copied from class: Decoder
      Reads a char-string written by Encoder.writeString(org.apache.avro.util.Utf8).
      Specified by:
      readString in class Decoder
      Throws:
      IOException

    • readString

      public String readString() throws IOException
      Description copied from class: Decoder
      Reads a char-string written by Encoder.writeString(org.apache.avro.util.Utf8).
      Specified by:
      readString in class Decoder
      Throws:
      IOException

    • skipString

      public void skipString() throws IOException
      Description copied from class: Decoder
      Discards a char-string written by Encoder.writeString(org.apache.avro.util.Utf8).
      Specified by:
      skipString in class Decoder
      Throws:
      IOException

    • readBytes

      public ByteBuffer readBytes(ByteBuffer old) throws IOException
      Description copied from class: Decoder
      Reads a byte-string written by Encoder.writeBytes(java.nio.ByteBuffer). if old is not null and has sufficient capacity to take in the bytes being read, the bytes are returned in old.
      Specified by:
      readBytes in class Decoder
      Throws:
      IOException

    • skipBytes

      public void skipBytes() throws IOException
      Description copied from class: Decoder
      Discards a byte-string written by Encoder.writeBytes(java.nio.ByteBuffer).
      Specified by:
      skipBytes in class Decoder
      Throws:
      IOException

    • readFixed

      public void readFixed(byte[] bytes, int start, int length) throws IOException
      Description copied from class: Decoder
      Reads fixed sized binary object.
      Specified by:
      readFixed in class Decoder
      Parameters:
      bytes - The buffer to store the contents being read.
      start - The position where the data needs to be written.
      length - The size of the binary object.
      Throws:
      IOException

    • skipFixed

      public void skipFixed(int length) throws IOException
      Description copied from class: Decoder
      Discards fixed sized binary object.
      Specified by:
      skipFixed in class Decoder
      Parameters:
      length - The size of the binary object to be skipped.
      Throws:
      IOException

    • readEnum

      public int readEnum() throws IOException
      Description copied from class: Decoder
      Reads an enumeration.
      Specified by:
      readEnum in class Decoder
      Returns:
      The enumeration's value.
      Throws:
      IOException

    • doSkipBytes

      protected void doSkipBytes(long length) throws IOException
      Throws:
      IOException

    • doReadBytes

      protected void doReadBytes(byte[] bytes, int start, int length) throws IOException
      Reads length bytes into bytes starting at start.
      Throws:
      EOFException - If there are not enough number of bytes in the source.
      IOException

    • doReadItemCount

      protected long doReadItemCount() throws IOException
      Returns the number of items to follow in the current array or map. Returns 0 if there are no more items in the current array and the array/map has ended. Arrays are encoded as a series of blocks. Each block consists of a long count value, followed by that many array items. A block with count zero indicates the end of the array. If a block's count is negative, its absolute value is used, and the count is followed immediately by a long block size indicating the number of bytes in the block.
      Throws:
      IOException - If the first byte cannot be read for any reason other than the end of the file, if the input stream has been closed, or if some other I/O error occurs.

    • readArrayStart

      public long readArrayStart() throws IOException
      Description copied from class: Decoder
      Reads and returns the size of the first block of an array. If this method returns non-zero, then the caller should read the indicated number of items, and then call Decoder.arrayNext() to find out the number of items in the next block. The typical pattern for consuming an array looks like: 
         for(long i = in.readArrayStart(); i != 0; i = in.arrayNext()) {
     for (long j = 0; j invalid input: '<' i; j++) {
       read next element of the array;
     }
   }
      Specified by:
      readArrayStart in class Decoder
      Throws:
      IOException

    • arrayNext

      public long arrayNext() throws IOException
      Description copied from class: Decoder
      Processes the next block of an array and returns the number of items in the block and let's the caller read those items.
      Specified by:
      arrayNext in class Decoder
      Throws:
      IOException

    • skipArray

      public long skipArray() throws IOException
      Description copied from class: Decoder
      Used for quickly skipping through an array. Note you can either skip the entire array, or read the entire array (with Decoder.readArrayStart()), but you can't mix the two on the same array. This method will skip through as many items as it can, all of them if possible. It will return zero if there are no more items to skip through, or an item count if it needs the client's help in skipping. The typical usage pattern is: 
         for(long i = in.skipArray(); i != 0; i = i.skipArray()) {
     for (long j = 0; j invalid input: '<' i; j++) {
       read and discard the next element of the array;
     }
   }
      Note that this method can automatically skip through items if a byte-count is found in the underlying data, or if a schema has been provided to the implementation, but otherwise the client will have to skip through items itself.
      Specified by:
      skipArray in class Decoder
      Throws:
      IOException

    • readMapStart

      public long readMapStart() throws IOException
      Description copied from class: Decoder
      Reads and returns the size of the next block of map-entries. Similar to Decoder.readArrayStart(). As an example, let's say you want to read a map of records, the record consisting of an Long field and a Boolean field. Your code would look something like this: 
       Mapinvalid input: '<'String, Record> m = new HashMapinvalid input: '<'String, Record>();
 Record reuse = new Record();
 for (long i = in.readMapStart(); i != 0; i = in.readMapNext()) {
   for (long j = 0; j invalid input: '<' i; j++) {
     String key = in.readString();
     reuse.intField = in.readInt();
     reuse.boolField = in.readBoolean();
     m.put(key, reuse);
   }
 }
      Specified by:
      readMapStart in class Decoder
      Throws:
      IOException

    • mapNext

      public long mapNext() throws IOException
      Description copied from class: Decoder
      Processes the next block of map entries and returns the count of them. Similar to Decoder.arrayNext(). See Decoder.readMapStart() for details.
      Specified by:
      mapNext in class Decoder
      Throws:
      IOException

    • skipMap

      public long skipMap() throws IOException
      Description copied from class: Decoder
      Support for quickly skipping through a map similar to Decoder.skipArray(). As an example, let's say you want to skip a map of records, the record consisting of an Long field and a Boolean field. Your code would look something like this: 
       for (long i = in.skipMap(); i != 0; i = in.skipMap()) {
   for (long j = 0; j invalid input: '<' i; j++) {
     in.skipString(); // Discard key
     in.readInt(); // Discard int-field of value
     in.readBoolean(); // Discard boolean-field of value
   }
 }
      Specified by:
      skipMap in class Decoder
      Throws:
      IOException

    • readIndex

      public int readIndex() throws IOException
      Description copied from class: Decoder
      Reads the tag of a union written by Encoder.writeIndex(int).
      Specified by:
      readIndex in class Decoder
      Throws:
      IOException

    • isEnd

      public boolean isEnd() throws IOException
      Returns true if the current BinaryDecoder is at the end of its source data and cannot read any further without throwing an EOFException or other IOException.

      Not all implementations of BinaryDecoder support isEnd(). Implementations that do not support isEnd() will throw a UnsupportedOperationException.

      Throws:
      IOException - If the first byte cannot be read for any reason other than the end of the file, if the input stream has been closed, or if some other I/O error occurs.

    • inputStream

      public InputStream inputStream()
      Returns an InputStream that is aware of any buffering that may occur in this BinaryDecoder. Readers that need to interleave decoding Avro data with other reads must access this InputStream to do so unless the implementation is 'direct' and does not read beyond the minimum bytes necessary from the source.