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88 lines
2.5 KiB
Java
88 lines
2.5 KiB
Java
An example of using ByteBuffer
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public static void main(String[] args)
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{
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// Create a ByteBuffer using a byte array
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byte[] bytes = new byte[10];
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ByteBuffer buf = ByteBuffer.wrap(bytes);
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// Create a non-direct ByteBuffer with a 10 byte capacity
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// The underlying storage is a byte array.
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buf = ByteBuffer.allocate(10);
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// Create a direct (memory-mapped) ByteBuffer with a 10 byte capacity.
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buf = ByteBuffer.allocateDirect(10);
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// Get the ByteBuffer's capacity
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int capacity = bbuf.capacity(); // 10
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// Use the absolute get(). This method does not affect the position.
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byte b = bbuf.get(5); // position=0
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// Set the position
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bbuf.position(5);
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// Use the relative get()
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b = bbuf.get();
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// Get the new position
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int pos = bbuf.position(); // 6
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// Get remaining byte count
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int rem = bbuf.remaining(); // 4
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// Set the limit
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bbuf.limit(7); // remaining=1
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// This convenience method sets the position to 0
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bbuf.rewind(); // remaining=7
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// Use the absolute put(). This method does not affect the position.
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bbuf.put((byte)0xFF); // position=0
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// Use the relative put()
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bbuf.put((byte)0xFF);
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// This convenience method sets the position to 0
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bbuf.rewind(); // remaining=7
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/*
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Use ByteBuffer to store Strings
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*/
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// Create a character ByteBuffer
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CharBuffer cbuf = buf.asCharBuffer();
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// Write a string
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cbuf.put("str");
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// Convert character ByteBuffer to a string.
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// Uses characters between current position and limit so flip it first
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cbuf.flip();
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String s = cbuf.toString(); // str Does not affect position
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// Get a substring
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int start = 2; // start is relative to cbuf's current position
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int end = 5;
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CharSequence sub = cbuf.subSequence(start, end); // str
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/*
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Set Byte Ordering for a ByteBuffer
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*/
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// Get default byte ordering
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ByteOrder order = buf.order(); // ByteOrder.BIG_ENDIAN
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// Put a multibyte value
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buf.putShort(0, (short)123);
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buf.get(0); // 0
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buf.get(1); // 123
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// Set to little endian
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buf.order(ByteOrder.LITTLE_ENDIAN);
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// Put a multibyte value
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buf.putShort(0, (short)123);
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buf.get(0); // 123
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buf.get(1); // 0
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}
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