connectionpooling.java

连接池示例

import java.util.ArrayList;
import java.util.List;
import java.sql.*;

public class ConnectionPooling {
	private static ConnectionPooling instance = new ConnectionPooling();;

	private List connectionList;

	private final String driver = "org.gjt.mm.mysql.Driver";

	private final String url = 
		"jdbc:mysql://localhost/test";

	private final String username = "root";

	private final String password = "123";
	
	
	//在构造函数中新建20个Connection对象，保存在ArrayList中，作为连接池
	private ConnectionPooling() {
		connectionList = new ArrayList();
		try {
			Class.forName(driver);
		} catch (ClassNotFoundException e) {
			System.out.println(e.getMessage());
		}
		try {
			for (int i = 0; i < 20; i++) {
				Connection conn = DriverManager.getConnection(url, username,
						password);
				connectionList.add(conn);
			}
		} catch (SQLException e) {
			System.out.println(e.getMessage());
		}
	}
	
	public static ConnectionPooling getInstance() {
		return instance;
	}
	
	//采用循环使用的方式从list中取出Connection对象使用
	public Connection getConnection() {
		if(connectionList.size() > 0)
			return (Connection)connectionList.remove(0);
		
		return null;
	}
	
	//收回使用过的Connection对象
	public void returnConnection(Connection conn){
		connectionList.add(conn);
		
	}
	
	
	
	
}