net.named_data.jndn.util

Class Blob

java.lang.Object

net.named_data.jndn.util.Blob

All Implemented Interfaces:

Comparable

Direct Known Subclasses:

SignedBlob

public class Blob
extends Object
implements Comparable

A Blob holds a pointer to an immutable ByteBuffer. We use an immutable buffer so that it is OK to pass the object into methods because the new or old owner can’t change the bytes. Note that the pointer to the ByteBuffer can be null.

Constructor Summary

Constructors

Constructor and Description
Blob() Create a new Blob with a null pointer.
Blob(Blob blob) Create a new Blob and take another pointer to the given blob's buffer.
Blob(byte[] value) Create a new Blob with a copy of the bytes in the array.
Blob(byte[] value, boolean copy) Create a new Blob from the the byte array.
Blob(ByteBuffer buffer, boolean copy) Create a new Blob from an existing ByteBuffer.
Blob(int[] value) Create a new Blob with a copy of the bytes in the array.
Blob(String value) Create a new Blob from the UTF-8 encoding of the Unicode string.

Method Summary

Methods

Modifier and Type	Method and Description
ByteBuffer	buf() Get the read-only ByteBuffer.
int	compare(Blob other) Compare this to the other Blob using byte-by-byte comparison from their position to their limit.
int	compareTo(Object o)
int	CompareTo(Object o)
boolean	equals(Blob other)
boolean	equals(Object other)
byte[]	getImmutableArray() Get a byte array by calling ByteBuffer.array() if possible (because the ByteBuffer slice covers the entire backing array).
int	hashCode() If the hash code is already computed then return it, otherwise compute and return the hash code.
boolean	isNull() Check if the buffer pointer is null.
int	size() Get the size of the buffer.
String	toHex() Return a hex string of buf() from position to limit.
static String	toHex(ByteBuffer buffer) Return a hex string of the contents of buffer from position to limit.
String	toString() Decode the byte array as UTF8 and return the Unicode string.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Blob

public Blob()

Create a new Blob with a null pointer.

Blob

public Blob(Blob blob)

Create a new Blob and take another pointer to the given blob's buffer.

Parameters:

blob - The Blob from which we take another pointer to the same buffer.

Blob

public Blob(ByteBuffer buffer,
    boolean copy)

Create a new Blob from an existing ByteBuffer. IMPORTANT: If copy is false, after calling this constructor, if you keep a pointer to the buffer then you must treat it as immutable and promise not to change it.

Parameters:

buffer - The existing ByteBuffer. It is important that the buffer position and limit are correct.

copy - If true, copy the contents into a new byte array. If false, just take a slice which uses the existing byte array in buffer.

Blob

public Blob(byte[] value,
    boolean copy)

Create a new Blob from the the byte array. IMPORTANT: If copy is false, after calling this constructor, if you keep a pointer to the buffer then you must treat it as immutable and promise not to change it.

Parameters:

value - The byte array. If copy is true, this makes a copy.

copy - If true, copy the contents into a new byte array. If false, just use ByteBuffer.wrap which uses the existing byte array.

Blob

public Blob(byte[] value)

Create a new Blob with a copy of the bytes in the array.

Parameters:

value - The byte array to copy.

Blob

public Blob(int[] value)

Create a new Blob with a copy of the bytes in the array.

Parameters:

value - The array of integer to copy where each integer is in the range 0 to 255.

Blob

public Blob(String value)

Create a new Blob from the UTF-8 encoding of the Unicode string.

Parameters:

value - The Unicode string which is encoded as UTF-8.

Method Detail

buf

public final ByteBuffer buf()

Get the read-only ByteBuffer.

Returns:

The read-only ByteBuffer using asReadOnlyBuffer(), or null if the pointer is null.

getImmutableArray

public final byte[] getImmutableArray()

Get a byte array by calling ByteBuffer.array() if possible (because the ByteBuffer slice covers the entire backing array). Otherwise return byte array as a copy of the ByteBuffer. This is called immutableArray to remind you not to change the contents of the returned array. This method is necessary because the read-only ByteBuffer returned by buf() doesn't allow you to call array().

Returns:

A byte array which you should not modify, or null if the pointer is null.

size

public final int size()

Get the size of the buffer.

Returns:

The length (remaining) of the ByteBuffer, or 0 if the pointer is null.

isNull

public final boolean isNull()

Check if the buffer pointer is null.

Returns:

True if the buffer pointer is null, otherwise false.

toHex

public final String toHex()

Return a hex string of buf() from position to limit.

Returns:

A string of hex bytes, or "" if the buffer is null.

toHex

public static String toHex(ByteBuffer buffer)

Return a hex string of the contents of buffer from position to limit.

Parameters:

buffer - The buffer.

Returns:

A string of hex bytes.

equals

public final boolean equals(Blob other)

equals

public boolean equals(Object other)

Overrides:

equals in class Object

compare

public final int compare(Blob other)

Compare this to the other Blob using byte-by-byte comparison from their position to their limit. If this and other are both isNull(), then this returns 0. If this isNull() and the other is not, return -1. If this is not isNull() and the other is, return 1. We compare explicitly because a Blob uses a ByteBuffer which compares based on signed byte, not unsigned byte.

Parameters:

other - The other Blob to compare with.

Returns:

0 If they compare equal, -1 if self is less than other, or 1 if self is greater than other. If both are equal up to the shortest, then return -1 if self is shorter than other, or 1 of self is longer than other.

compareTo

public final int compareTo(Object o)

Specified by:

compareTo in interface Comparable

CompareTo

public final int CompareTo(Object o)

hashCode

public int hashCode()

If the hash code is already computed then return it, otherwise compute and return the hash code.

Overrides:

hashCode in class Object

Returns:

The hash code for the buffer, or 0 if the buffer is null.

toString

public String toString()

Decode the byte array as UTF8 and return the Unicode string.

Overrides:

toString in class Object

Returns:

A unicode string, or "" if the buffer is null.