可供参考的【数据库连接池(DBCP)】2

import java.sql.Connection;import java.sql.DriverManager;import java.sql.SQLException;import java.util.Properties;import java.util.Vector;public class PersonDefine_ConnectionPool implements Runnable {public  String ProductionDB = "axdb_tmp";//的默值private String database_driver = "com.microsoft.sqlserver.jdbc.SQLServerDriver";//的默值// private String// dakabase_url="jdbc:sybase:Tds:IP:port/dakabase_test?useUnicode=true&characterEncoding=UTF-8";private String database_url = "jdbc:sqlserver://localhost:1433;DatabaseName=mgr_live"; //的默值private String username = "sa";private String password = "12345678";private int maxConnections = 50;private boolean waitIfBusy = true;private Vector availableConnections, busyConnections;private boolean connectionPending = false;public PersonDefine_ConnectionPool(Properties props) throws SQLException {System.out.println("jdbc:PersonDefine_ConnectionPool...");int initialConnections = 0;this.ProductionDB = props.getProperty("ELITEDATA.ProductionDB");this.database_driver = props.getProperty("ELITEDATA.database_driver").trim();this.database_url = props.getProperty("ELITEDATA.database_url");this.username=props.getProperty("ELITEDATA.database_username");this.password=props.getProperty("ELITEDATA.database_password");this.maxConnections = maxConnections;this.waitIfBusy = waitIfBusy;if (initialConnections > maxConnections) {initialConnections = maxConnections;}availableConnections = new Vector(initialConnections);busyConnections = new Vector();for (int i = 0; i < initialConnections; i++) {availableConnections.addElement(makeNewConnection());}}public synchronized Connection getConnection() throws SQLException {System.out.println("jdbc:Get PersonDefine_ConnectionPool...");if (!availableConnections.isEmpty()) {Connection existingConnection = (Connection) availableConnections.lastElement();int lastIndex = availableConnections.size() - 1;availableConnections.removeElementAt(lastIndex);// If connection on available list is closed (e.g.,// it timed out), then remove it from available list// and repeat the process of obtaining a connection.// Also wake up threads that were waiting for a// connection because maxConnection limit was reached.if (existingConnection.isClosed()) {notifyAll(); // Freed up a spot for anybody waitingreturn (getConnection());} else {busyConnections.addElement(existingConnection);return (existingConnection);}} else {// Three possible cases:// 1) You haven't reached maxConnections limit. So// establish one in the background if there isn't// already one pending, then wait for// the next available connection (whether or not// it was the newly established one).// 2) You reached maxConnections limit and waitIfBusy// flag is false. Throw SQLException in such a case.// 3) You reached maxConnections limit and waitIfBusy// flag is true. Then do the same thing as in second// part of step 1: wait for next available connection.if ((totalConnections() < maxConnections) && !connectionPending) {makeBackgroundConnection();} else if (!waitIfBusy) {throw new SQLException("PersonDefine_ConnectionPool limit reached");}// Wait for either a new connection to be established// (if you called makeBackgroundConnection) or for// an existing connection to be freed up.try {wait();} catch (InterruptedException ie) {}// Someone freed up a connection, so try again.return (getConnection());}}// You can't just make a new connection in the foreground// when none are available, since this can take several// seconds with a slow network connection. Instead,// start a thread that establishes a new connection,// then wait. You get woken up either when the new connection// is established or if someone finishes with an existing// connection.private void makeBackgroundConnection() {connectionPending = true;System.out.println("jdbc:Make Background PersonDefine_ConnectionPool...");try {Thread connectThread = new Thread(this);connectThread.start();} catch (OutOfMemoryError oome) {System.out.println("jdbc:PersonDefine_ConnectionPool out of Memory..." + oome);}}public void run() {try {System.out.println("jdbc:run PersonDefine_ConnectionPool...");Connection connection = makeNewConnection();synchronized (this) {availableConnections.addElement(connection);connectionPending = false;notifyAll();}} catch (Exception e) { // SQLException or OutOfMemorySystem.out.println("jdbc:PersonDefine_ConnectionPool out of Memory...");}}// This explicitly makes a new connection. Called in// the foreground when initializing the ConnectionPool,// and called in the background when running.private Connection makeNewConnection() throws SQLException {try {System.out.println("jdbc:make new PersonDefine_ConnectionPool...");// Load database dakabase_driver if not already loadedClass.forName(database_driver);// Establish network connection to databaseConnection connection = DriverManager.getConnection(database_url, username, password);return (connection);} catch (ClassNotFoundException cnfe) {// Simplify try/catch blocks of people using this by// throwing only one exception type.System.out.println("jdbc:PersonDefine_ConnectionPool Can't find class for database_driver:");throw new SQLException("Can't find class for PersonDefine_ConnectionPool: " + database_driver);}}public synchronized void free(Connection connection) {System.out.println("jdbc:free PersonDefine_ConnectionPool...");busyConnections.removeElement(connection);availableConnections.addElement(connection);// Wake up threads that are waiting for a connectionnotifyAll();}public synchronized int totalConnections() {return (availableConnections.size() + busyConnections.size());}/** * Close all the connections. Use with caution: be sure no connections are * in use before calling. Note that you are not <I>required</I> to call * this when done with a ConnectionPool, since connections are guaranteed to * be closed when garbage collected. But this method gives more control * regarding when the connections are closed. */public synchronized void closeAllConnections() {System.out.println("jdbc:close all PersonDefine_ConnectionPool...");closeConnections(availableConnections);availableConnections = new Vector();closeConnections(busyConnections);busyConnections = new Vector();}private void closeConnections(Vector connections) {try {System.out.println("jdbc:close PersonDefine_ConnectionPool...");for (int i = 0; i < connections.size(); i++) {Connection connection = (Connection) connections.elementAt(i);if (!connection.isClosed()) {connection.close();}}} catch (SQLException sqle) {System.out.println("jdbc: PersonDefine_ConnectionPool..." + sqle);}}public synchronized String toString() {String info = "ConnectionPool(PersonDefine_ConnectionPool)(" + database_url + "," + username + ")" + ", available=" + availableConnections.size() + ", busy="+ busyConnections.size() + ", max=" + maxConnections;return (info);}}