commons-pool对象池实例（二）

改造上一篇的代码，实现了KeyedObjectPool.

对象池实现类：

package com.my.pool.pooledobject;

import org.apache.commons.pool2.KeyedObjectPool;

public class KeyedPooledStringBuffer {
	private KeyedObjectPool<String,StringBuffer> pool;
	
	public KeyedPooledStringBuffer(KeyedObjectPool<String,StringBuffer> pool) {
		this.pool = pool;
	}
	
	public boolean print(String key,String data) {
		boolean flag = false;
		if(pool!=null&&key!=null) {
			StringBuffer buf = null;
			try{
				buf = pool.borrowObject(key);
				buf.append(data);
				System.out.println(buf.toString());
				return true;
			}catch(Exception e) {
				e.printStackTrace();
			}finally {
				try {
					if(buf != null) {
						pool.returnObject(key, buf);
					}
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		}
		
		return flag;
	}
	
}

工厂类：

package com.my.pool.pooledobject;

import org.apache.commons.pool2.BaseKeyedPooledObjectFactory;
import org.apache.commons.pool2.PooledObject;
import org.apache.commons.pool2.impl.DefaultPooledObject;

/**
 * 先创建，后打包
 *
 */
public class KeyedPooledStringBufferFactory extends BaseKeyedPooledObjectFactory<String,StringBuffer>{

	@Override
	public StringBuffer create(String key) throws Exception {
		StringBuffer buf = new StringBuffer();
		//根据key的不同进行不同的操作
		if("hello".equals(key)) {
			buf.append(key);
			buf.append("\t");
		}else {
			//Do nothing.
		}
		return buf;
	}

	@Override
	public PooledObject<StringBuffer> wrap(StringBuffer obj) {
		return new DefaultPooledObject<StringBuffer>(obj);
	}
	
	@Override
	/**
	 * 归还后调用的方法
	 */
	public void passivateObject(String key,PooledObject<StringBuffer> pooledObject) {
		StringBuffer buf = pooledObject.getObject();
		buf.setLength(0);
		if("hello".equals(key)) {
			buf.append(key);
			buf.append("\t");
		}else {
			//Do nothing.
		}
	}
}

主类：

package com.my.pool.main;

import org.apache.commons.pool2.impl.GenericKeyedObjectPool;
import org.apache.commons.pool2.impl.GenericKeyedObjectPoolConfig;

import com.my.pool.pooledobject.KeyedPooledStringBuffer;
import com.my.pool.pooledobject.KeyedPooledStringBufferFactory;

public class KeyedMainClass {
	public static void main(String[] args) {
		GenericKeyedObjectPoolConfig config = new GenericKeyedObjectPoolConfig();
		//最长等待分配时间
		config.setMaxWaitMillis(1000l);
		//每种key池内最多对象数
		config.setMaxTotalPerKey(100);
		//每种key池内最大空闲数目
		config.setMaxIdlePerKey(20);
		//每种key池内最小空闲数目
		config.setMinIdlePerKey(10);
		
		GenericKeyedObjectPool<String,StringBuffer> pool = new GenericKeyedObjectPool<String,StringBuffer>(new KeyedPooledStringBufferFactory());
		
		KeyedPooledStringBuffer bufUtil = new KeyedPooledStringBuffer(pool);
		bufUtil.print("hello","OK");
		bufUtil.print("else","OK");
	}
}

      KeyedObjectPool和ObjectPool的区别在于对于输入的key可以做不一样的操作，甚至获得不同的线程池。本例是在创建的时候，加入了一些字符，并在回收之后把前缀又写回去。不同的用法，可以自己发挥想象。