package org.rui.util;

import java.util.ArrayList;

/**

* 对象复用模式

*

* @author PC

*

*/

public class PoolManager

{

//连接池对象

public static class PoolItem

{

boolean inUse = false;

Object item;//池数据

PoolItem(Object item)

{

this.item = item;

}

}

//连接池集合

private ArrayList items = new ArrayList();

public void add(Object item)

{

this.items.add(new PoolItem(item));

}

static class EmptyPoolException extends Exception

{

}

public Object get() throws EmptyPoolException

{

for (int i = 0; i < items.size(); i++)

{

PoolItem pitem = (PoolItem) items.get(i);

if (pitem.inUse == false)

{

pitem.inUse = true;

return pitem.item;

}

}

throw new EmptyPoolException();

// return null;

}

/**

* 释放连接

* @param item

*/

public void release(Object item)

{

for (int i = 0; i < items.size(); i++)

{

PoolItem pitem = (PoolItem) items.get(i);

if (item == pitem.item)

{

pitem.inUse = false;

return;

}

}

throw new RuntimeException(item + " not null");

}

}

package org.rui.util;

import org.junit.Test;

/**

* 对象池(Object pool)

*

* 并没有限制说只能创建一个对象。这种技术同样适用于创建固定数量的对象，但

* 是，这种情况下，你就得面对如何共享对象池里的对象这种问题。如果共享对象很成

* 问题得话，你可以考虑以签入(check-in)签出(check-out)共享对象作为一种解决

* 方案。比如，就数据库来说，商业数据库通常会限制某一时刻可以使用的连接的个 数。下面这个例子就用对象池(object

* pool)实现了对这些数据库连接的管理。首 先，对象池对象(a pool of objects)的基本管理是作为一个单独的类来实现的。

*

* @author PC

*

*/

interface Connection

{

Object get();

void set(Object x);

}

class ConnectionImplementation implements Connection

{

public Object get()

{

return null;

}

public void set(Object s)

{

}

}

class ConnectionPool

{

//池管理对象

private static PoolManager pool = new PoolManager();

//指定连接数 并添加

public static void addConnections(int number)

{

for (int i = 0; i < number; i++)

pool.add(new ConnectionImplementation());

}

//获取连接

public static Connection getConnection()

throws PoolManager.EmptyPoolException

{

return (Connection) pool.get();

}

//释放指定的连接

public static void releaseConnection(Connection c)

{

pool.release(c);

}

}

//演示使用

public class ConnectionPoolDemo

{

static

{

ConnectionPool.addConnections(5);

}

@Test

public void test()

{

Connection c = null;

try

{

// 获得连接

c = ConnectionPool.getConnection();

} catch (PoolManager.EmptyPoolException e)

{

throw new RuntimeException(e);

}

// 设值

c.set(new Object());

//获取

c.get();

// 释放

ConnectionPool.releaseConnection(c);

}

@Test

public void test2()

{

Connection c = null;

try

{

c = ConnectionPool.getConnection();

} catch (PoolManager.EmptyPoolException e)

{

throw new RuntimeException(e);

}

c.set(new Object());

c.get();

ConnectionPool.releaseConnection(c);

}

public static void main(String args[])

{

// junit.textui.TestRunner.run(ConnectionPoolDemo.class);

}

}