- * This class can also be used for receiving data from the network. - *
- * Note that for all method below where the buffer length passed by the
- * caller cannot exceed the actually length of the byte array passed as
- * the buffer, if this condition is not true, then the method silently
- * reduces the length value to maximum allowable value.
- *
- * Written using on-line Java Platform 1.2 API Specification, as well
- * as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998).
- * Status: Believed complete and correct.
- *
- * @author Warren Levy DatagramPacket
- * which has the specified buffer, offset, and length.
- *
- * @param buf The buffer for holding the incoming datagram.
- * @param offset The offset into the buffer to start writing.
- * @param length The maximum number of bytes to read.
- *
- * @since Java 1.2
- */
- public DatagramPacket(byte[] buf, int offset, int length)
- {
- if (buf == null)
- throw new NullPointerException("Null buffer");
- if (offset < 0)
- throw new IllegalArgumentException("Invalid offset: " + offset);
- if (length < 0)
- throw new IllegalArgumentException("Invalid length: " + length);
- if (offset + length > buf.length)
- throw new IllegalArgumentException("Potential buffer overflow - offset: "
- + offset + " length: " + length);
-
- buffer = buf;
- this.offset = offset;
- this.length = length;
- this.address = null;
- this.port = -1;
- }
-
-/**
- * Initializes a new instance of DatagramPacket for
- * receiving packets from the network.
- *
- * @param buf A buffer for storing the returned packet data
- * @param length The length of the buffer (must be <= buf.length)
- */
- public DatagramPacket(byte[] buf, int length)
- {
- this(buf, 0, length);
- }
-
-/**
- * Initializes a new instance of DatagramPacket for
- * transmitting packets across the network.
- *
- * @param buf A buffer containing the data to send
- * @param offset The offset into the buffer to start writing from.
- * @param len The length of the buffer (must be <= buf.length)
- * @param addr The address to send to
- * @param port The port to send to
- *
- * @since Java 1.2
- */
- public DatagramPacket(byte[] buf, int offset, int length,
- InetAddress address, int port)
- {
- if (buf == null)
- throw new NullPointerException("Null buffer");
- if (offset < 0)
- throw new IllegalArgumentException("Invalid offset: " + offset);
- if (length < 0)
- throw new IllegalArgumentException("Invalid length: " + length);
- if (offset + length > buf.length)
- throw new IllegalArgumentException("Potential buffer overflow - offset: "
- + offset + " length: " + length);
- if (port < 0 || port > 65535)
- throw new IllegalArgumentException("Invalid port: " + port);
- if (address == null)
- throw new NullPointerException("Null address");
-
- buffer = buf;
- this.offset = offset;
- this.length = length;
- this.address = address;
- this.port = port;
- }
-
-/**
- * Initializes a new instance of DatagramPacket for
- * transmitting packets across the network.
- *
- * @param buf A buffer containing the data to send
- * @param length The length of the buffer (must be <= buf.length)
- * @param address The address to send to
- * @param port The port to send to
- */
- public DatagramPacket(byte[] buf, int length, InetAddress address, int port)
- {
- this(buf, 0, length, address, port);
- }
-
-/**
- * Returns the address that this packet is being sent to or, if it was used
- * to receive a packet, the address that is was received from. If the
- * constructor that doesn not take an address was used to create this object
- * and no packet was actually read into this object, then this method
- * returns null.
- *
- * @return The address for this packet.
- */
- public synchronized InetAddress getAddress()
- {
- return address;
- }
-
-/**
- * Returns the port number this packet is being sent to or, if it was used
- * to receive a packet, the port that it was received from. If the
- * constructor that doesn not take an address was used to create this object
- * and no packet was actually read into this object, then this method
- * will return 0.
- *
- * @return The port number for this packet
- */
- public synchronized int getPort()
- {
- return port;
- }
-
-/**
- * Returns the data buffer for this packet
- *
- * @return This packet's data buffer
- */
- public synchronized byte[] getData()
- {
- return buffer;
- }
-
-/**
- * This method returns the current offset value into the data buffer
- * where data will be sent from.
- *
- * @return The buffer offset.
- *
- * @since Java 1.2
- */
- public synchronized int getOffset()
- {
- return offset;
- }
-
-/**
- * Returns the length of the data in the buffer
- *
- * @return The length of the data
- */
- public synchronized int getLength()
- {
- return length;
- }
-
-/**
- * This sets the address to which the data packet will be transmitted.
- *
- * @param addr The destination address
- */
- public synchronized void setAddress(InetAddress iaddr)
- {
- if (iaddr == null)
- throw new NullPointerException("Null address");
-
- address = iaddr;
- }
-
-/**
- * This sets the port to which the data packet will be transmitted.
- *
- * @param port The destination port
- */
- public synchronized void setPort(int iport)
- {
- if (iport < 0 || iport > 65535)
- throw new IllegalArgumentException("Invalid port: " + iport);
-
- port = iport;
- }
-
-/**
- * Sets the data buffer for this packet.
- *
- * @param buf The new buffer for this packet
- */
- public synchronized void setData(byte[] buf)
- {
- // This form of setData requires setLength to be called separately
- // and subsequently.
- if (buf == null)
- throw new NullPointerException("Null buffer");
-
- buffer = buf;
- }
-
-/**
- * This method sets the data buffer for the packet.
- *
- * @param buf The byte array containing the data for this packet.
- * @param offset The offset into the buffer to start reading data from.
- * @param length The number of bytes of data in the buffer.
- *
- * @since Java 1.2
- */
- public synchronized void setData(byte[] buf, int offset, int length)
- {
- // This form of setData must be used if offset is to be changed.
-
- if (buf == null)
- throw new NullPointerException("Null buffer");
- if (offset < 0)
- throw new IllegalArgumentException("Invalid offset: " + offset);
- if (length < 0)
- throw new IllegalArgumentException("Invalid length: " + length);
- if (offset + length > buf.length)
- throw new IllegalArgumentException("Potential buffer overflow - offset: "
- + offset + " length: " + length);
-
- buffer = buf;
- this.offset = offset;
- this.length = length;
- }
-
-/**
- * Sets the length of the data in the buffer.
- *
- * @param length The new length. (Where len <= buf.length)
- */
- public synchronized void setLength(int length)
- {
- if (length < 0)
- throw new IllegalArgumentException("Invalid length: " + length);
- if (offset + length > buffer.length)
- throw new IllegalArgumentException("Potential buffer overflow - offset: "
- + offset + " length: " + length);
-
- this.length = length;
- }
-} // class DatagramPacket
-