driverClassName=oracle.jdbc.driver.OracleDriverusername=scottpassword=tigerurl=jdbc:oracle:thin:@192.168.1.20:1521:ora9poolSize=10

package webbook.util;import java.io.FileInputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;
import java.util.Vector;public class ConnectionPool {private Vector<Connection> pool;private String url;private String username;private String password;private String driverClassName;/*** 连接池的大小，也就是连接池中有多少个数据库连接。*/private int poolSize = 1;private static ConnectionPool instance = null;/*** 私有的构造方法，禁止外部创建本类的对象，要想获得本类的对象，通过<code>getIstance</code>方法。* 使用了设计模式中的单子模式。*/private ConnectionPool() {init();}/*** 连接池初始化方法，读取属性文件的内容 建立连接池中的初始连接*/private void init() {pool = new Vector<Connection>(poolSize);readConfig();addConnection();}/*** 返回连接到连接池中*/public synchronized void release(Connection conn) {pool.add(conn);}/*** 关闭连接池中的所有数据库连接*/public synchronized void closePool() {for (int i = 0; i < pool.size(); i++) {try {((Connection) pool.get(i)).close();} catch (SQLException e) {e.printStackTrace();}pool.remove(i);}}/*** 返回当前连接池的一个对象*/public static ConnectionPool getInstance() {if (instance == null) {instance = new ConnectionPool();}return instance;}/*** 返回连接池中的一个数据库连接*/public synchronized Connection getConnection() { if (pool.size() > 0) {Connection conn = pool.get(0);pool.remove(conn);return conn;} else {return null;}}/*** 在连接池中创建初始设置的的数据库连接*/private void addConnection() {Connection conn = null;for (int i = 0; i < poolSize; i++) {try {Class.forName(driverClassName);conn = java.sql.DriverManager.getConnection(url, username, password);pool.add(conn);} catch (ClassNotFoundException e) {e.printStackTrace();} catch (SQLException e) {e.printStackTrace();}}}/*** 读取设置连接池的属性文件*/private void readConfig() {try {String path = System.getProperty("user.dir") + "\\dbpool.properties";FileInputStream is = new FileInputStream(path);Properties props = new Properties();props.load(is);this.driverClassName = props.getProperty("driverClassName");this.username = props.getProperty("username");this.password = props.getProperty("password");this.url = props.getProperty("url");this.poolSize = Integer.parseInt(props.getProperty("poolSize"));} catch (Exception e) {e.printStackTrace();System.err.println("读取属性文件出错. ");        }}
}

package webbook.util;import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;public class ConnectionPoolTest {public static void main(String[] args) throws Exception {String sql = "select id,name,phone from guestbook";long start = System.currentTimeMillis();ConnectionPool pool = null;for (int i = 0; i < 100; i++) {pool = ConnectionPool.getInstance();Connection conn = pool.getConnection();Statement stmt = conn.createStatement();ResultSet rs = stmt.executeQuery(sql);while (rs.next()) {}rs.close();stmt.close();pool.release(conn);}pool.closePool();System.out.println("经过100次的循环调用，使用连接池花费的时间:" + (System.currentTimeMillis() - start) + "ms\n");String hostName = "192.168.1.20";String driverClass = "oracle.jdbc.driver.OracleDriver";String url = "jdbc:oracle:thin:@" + hostName + ":1521:ora9";String user = "scott";String password = "tiger";start = System.currentTimeMillis();for (int i = 0; i < 100; i++) {Class.forName(driverClass);Connection conn = DriverManager.getConnection(url, user, password);Statement stmt = conn.createStatement();ResultSet rs = stmt.executeQuery(sql);while (rs.next()) {}rs.close();stmt.close();conn.close();}System.out.println("经过100次的循环调用，不使用连接池花费的时间:" + (System.currentTimeMillis() - start) + "ms");}
}