源码来源于http://www.toutiao.com/a6350448676050174209/，留存以供以后参考学习
先上一张项目托普图
然后分别列出各个文件的源码：
MyPool.java（就是个接口）
package com.audi;
public interface MyPool
{
PoolConnection getConnection();
void createConnections(int count);
}
MyPoolImpl.java（接口的实现类）
package com.audi;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;
import java.util.Vector;
import com.mysql.jdbc.Driver;
public class MyPoolImpl implements MyPool
{
private static String jdbcDriver = "";
private static String jdbcUrl = "";
private static String userName = "";
private static String password = "";
private static int initCount;
private static int stepSize;
private static int poolMaxSize;
private static Vector<PoolConnection> poolConnections = new Vector<PoolConnection>();
public MyPoolImpl()
{
// TODO Auto-generated constructor stub
init();
}
private void init()
{
// TODO Auto-generated method stub
// 读取配置文件
InputStream in = MyPoolImpl.class.getClassLoader()
.getResourceAsStream("mysqlConnection.properties");
// InputStream inputStream = new in
Properties pro = new Properties();
try
{
// 装载配置文件输入流
pro.load(in);
} catch (Exception e)
{
// TODO: handle exception
}
// 从配置文件中读取出配置参数
jdbcDriver = pro.getProperty("jdbcDriver");
jdbcUrl = pro.getProperty("jdbcUrl");
userName = pro.getProperty("userName");
password = pro.getProperty("password");
initCount = Integer.valueOf(pro.getProperty("initCount"));
stepSize = Integer.valueOf(pro.getProperty("stepSize"));
poolMaxSize = Integer.valueOf(pro.getProperty("poolMaxSize"));
try
{
// 获取驱动对象并注册
Driver driver = (Driver) Class.forName(jdbcDriver).newInstance();
DriverManager.registerDriver(driver);
} catch (Exception e)
{
// TODO: handle exception
e.printStackTrace();
}
// 创建一定数量的初始链接
createConnections(initCount);
}
@Override
public PoolConnection getConnection()
{
// TODO Auto-generated method stub
if (poolConnections.size() <= 0)
{
System.out.println("链接池为空，获取数据库链接失败！！！");
throw new RuntimeException("链接池为空，获取数据库链接失败！！！");
}
PoolConnection connection = getRealConnection();
// 如果没有成功的获取链接就创建一定数量的链接 并从中获取一个有效链接
while(connection == null)
{
createConnections(stepSize);
connection = getRealConnection();
try
{
// 这里睡眠的原因时考虑到第一次获取链接失败，可能有多个线程在等待链接资源，所以当前线程先等待一下，避开高峰
Thread.sleep(300);
} catch (Exception e)
{
// TODO: handle exception
e.printStackTrace();
}
}
return connection;
}
// 注意有synchronized关键字
private synchronized PoolConnection getRealConnection()
{
// TODO Auto-generated method stub
for (PoolConnection conn : poolConnections)
{
// 如果当前链接空闲则返回该链接对象
if (!conn.isBusy())
{
Connection connection = conn.getConn();
try
{
// 判断获得的链接是否是有效的，如果无效就创建一个新的链接 isValid方法其实就是在定时时间到的时候执行一下sql语句
if (!connection.isValid(2000))
{
Connection validConn = DriverManager.getConnection(jdbcUrl, userName, password);
conn.setConn(validConn);
}
} catch (Exception e)
{
// TODO: handle exception
}
}
conn.setBusy(true);
return conn;
}
return null;
}
// 创建链接
@Override
public void createConnections(int count)
{
// TODO Auto-generated method stub
if (poolMaxSize > 0 && poolConnections.size() + count > poolMaxSize)
{
System.out.println("创建链接对象失败，因为数据库链接数量已达上限！！");
throw new RuntimeException("创建链接对象失败，因为数据库链接数量已达上限！！");
}
// 否则就开始创建链接
for (int i = 0; i < count; i++)
{
try
{
Connection conn = DriverManager.getConnection(jdbcUrl, userName, password);
// 封装链接对象 并存入vecter
PoolConnection poolConnection = new PoolConnection(conn, false);
poolConnections.add(poolConnection);
} catch (SQLException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
PoolConnection.java（里面会进行一些连接参数的配置）
package com.audi;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
public class PoolConnection
{
private Connection conn;
private boolean isBusy = false;
public Connection getConn()
{
return conn;
}
public void setConn(Connection conn)
{
this.conn = conn;
}
public boolean isBusy()
{
return isBusy;
}
public void setBusy(boolean isBusy)
{
this.isBusy = isBusy;
}
public PoolConnection(Connection conn,boolean isBusy)
{
this.conn = conn;
this.isBusy = isBusy;
}
public ResultSet querySql(String sql)
{
ResultSet resultSet = null;
Statement statement = null;
try
{
statement = conn.createStatement();
resultSet = statement.executeQuery(sql);
} catch (Exception e)
{
// TODO: handle exception
}
return resultSet;
}
public void close()
{
this.isBusy = false;
}
}
PoolManager.java（使用内部类的方式获取连接池对象）
package com.audi;
public class PoolManager
{
private static class CreatePool
{
private static MyPoolImpl myPoolImpl= new MyPoolImpl();
}
public static MyPoolImpl getInStance()
{
return CreatePool.myPoolImpl;
}
}
最后是测试类
package com.audi;
import java.sql.ResultSet;
public class TestPool
{
private static MyPoolImpl poolImpl =PoolManager.getInStance();
public static void main(String[] args)
{
// TODO Auto-generated method stub
/*long time= System.currentTimeMillis();
for (int i = 0; i < 2000; i++)
{
System.out.println("第"+i+"次执行");
selecData();
}
System.out.println("運行時間"+(System.currentTimeMillis()-time));*/
// System.out.println(new Date());
//selecData();
// 创建2000个数据库链接线程
long time= System.currentTimeMillis();
for (int i = 0; i < 2000; i++)
{
System.out.println("第"+i+"次执行");
new Thread(new Runnable()
{
public void run()
{
selecData();
}
});
}
System.out.println("運行時間"+(System.currentTimeMillis()-time));
}
public synchronized static void selecData()
{
PoolConnection connection = poolImpl.getConnection();
ResultSet resultSet = connection.querySql("select * from Student");
try
{
while (resultSet.next())
{
System.out.println(resultSet.getString("ID")+" "+resultSet.getString("NAME")+" "+resultSet.getString("AGE"));
}
resultSet.close();
connection.close();
} catch (Exception e)
{
// TODO: handle exception
e.printStackTrace();
}
}
}
数据库连接参数配置文件
mysqlConnection.properties
jdbcDriver=com.mysql.jdbc.Driver jdbcUrl=jdbc:mysql://localhost:3306/test userName=root password=w513723 initCount=10 stepSize=5 poolMaxSize=200