File	Doc	Category	Size	Date	Package
StreamConnectionPool.java	API Doc	J2ME MIDP 2.0	8697	Thu Nov 07 12:02:22 GMT 2002	com.sun.midp.io.j2me.http

StreamConnectionPool

• java.lang.Object

Fields Summary
private long	m_connectionLingerTime How long a connection can linger after its last use.
private Vector	m_connections internal connection hash table
private int	m_max_connections maximum connections

Constructors Summary

StreamConnectionPool(int number_of_connections, long connectionLingerTime) Create a new instance of this class. We are initially unconnected this will create the first connection. param number_of_connections initial number of connections must greater than zero. param connectionLingerTime how many millseconds a connection should stay in the pool after its last use this.m_max_connections = number_of_connections; this.m_connectionLingerTime = connectionLingerTime; m_connections = new Vector(m_max_connections);

Methods Summary
synchronized boolean	add(java.lang.String p_protocol, java.lang.String p_host, int p_port, javax.microedition.io.StreamConnection sc, java.io.DataOutputStream dos, java.io.DataInputStream dis) Tries to add a reuseable connection to the connection pool. Replace any not in use connections to the same host and port. Will not add to the same host and port in use. Will replace oldest not in use element (if any) if the pool is full. param p_protocol The protocol for the connection param p_host The Hostname for the connection param p_port The port number for the connection param sc The base stream connection param dos The data output stream from the base connection param dis The data input stream from the base connection return true if the connection was added, otherwise false StreamConnectionElement oldestNotInUse = null; // find the last unused element Enumeration cons = m_connections.elements(); while (cons.hasMoreElements()) { StreamConnectionElement sce = (StreamConnectionElement)cons.nextElement(); if (sce.m_in_use) { if (p_host.equals(sce.m_host) && p_port == sce.m_port) { return false; } continue; } // if the connection is a duplicate, delete it if (p_host.equals(sce.m_host) && p_port == sce.m_port) { // no protocol duplicates on host and port sce.close(); m_connections.removeElement(sce); break; } else { if (oldestNotInUse == null || sce.m_time < oldestNotInUse.m_time) { // save the oldest not in use, it may be removed later oldestNotInUse = sce; } } } /* * first check and see if the maximum number of connections * has been reached - if so delete the first one in the list (FIFO) * or * if this port and host are already in the pool. */ if (m_connections.size() >= m_max_connections) { if (oldestNotInUse == null) { return false; } oldestNotInUse.close(); m_connections.removeElement(oldestNotInUse); } m_connections.addElement(new StreamConnectionElement(p_protocol, p_host, p_port, sc, dos, dis)); return true;
synchronized StreamConnectionElement	get(java.lang.String p_protocol, java.lang.String p_host, int p_port) get an available connection and set the boolean flag to true (unavailable) in the connection pool. Also removes any stale connections, since this method gets called more than add or remove. param p_protocol The protocol for the connection param p_host The Hostname for the connection param p_port The port number for the connection return A stream connection element or null if not found StreamConnectionElement result = null; long c_time = System.currentTimeMillis(); Enumeration cons = m_connections.elements(); while (cons.hasMoreElements()) { StreamConnectionElement sce = (StreamConnectionElement)cons.nextElement(); if ((c_time - sce.m_time) > m_connectionLingerTime) { if (!sce.m_in_use) { sce.close(); } else { // signal returnToUse() to close sce.m_removed = true; } m_connections.removeElement(sce); continue; } if (p_host.equals(sce.m_host) && p_port == sce.m_port && p_protocol.equals(sce.m_protocol) && !sce.m_in_use) { result = sce; // do not break out so old connections can be removed continue; } } if (result != null) { result.m_in_use = true; } return result;
synchronized void	remove(StreamConnectionElement sce) Close connection and remove an instance of the stream connection element from the connection pool. param sce The stream connection element to remove sce.close(); m_connections.removeElement(sce);
synchronized void	returnForReuse(StreamConnectionElement returned) Return an instance of the stream connection element to the connection pool so it can be reused. It is done in the method so it can be synchronized with the get method. param returned The stream connection element to return returned.m_in_use = false; if (returned.m_removed) { // the connection was out too long returned.close(); return; } returned.m_time = System.currentTimeMillis();