摘要：使用提供了中對(duì)象池管理方式，它們的使用方式基本一樣，這里以對(duì)象池為例介紹其使用方式，一般實(shí)現(xiàn)自己的對(duì)象池需要經(jīng)過(guò)個(gè)步驟實(shí)現(xiàn)接口該接口是一種工廠模式，實(shí)現(xiàn)其目的是讓對(duì)象池通過(guò)該工廠模式創(chuàng)建管理的對(duì)象創(chuàng)建對(duì)象池實(shí)例創(chuàng)建對(duì)象池我們假設(shè)對(duì)象是一
common-pool2 使用
common-pool2提供了3中對(duì)象池管理方式，它們的使用方式基本一樣，這里以GenericObjectPool對(duì)象池為例介紹其使用方式，一般實(shí)現(xiàn)自己的對(duì)象池需要經(jīng)過(guò)2個(gè)步驟
實(shí)現(xiàn)PooledObjectFactory接口:該接口是一種工廠模式，實(shí)現(xiàn)其目的是讓對(duì)象池通過(guò)該工廠模式創(chuàng)建管理的對(duì)象
創(chuàng)建對(duì)象池(GenericObjectPool(PooledObjectFactory))實(shí)例
創(chuàng)建Conn對(duì)象池
我們假設(shè)Conn對(duì)象是一個(gè)建立TCP連接的對(duì)象，該對(duì)象的初始化時(shí)間平均為500ms，為了避免在程序中頻繁創(chuàng)建Conn對(duì)象，我們需要借助對(duì)象池管理Conn對(duì)象實(shí)例
import org.slf4j.LoggerFactory;
/**
* common-pool2 使用方式
*
* 假設(shè)這是一個(gè)建立TCP連接的對(duì)象，該對(duì)象的初始化時(shí)間平均為500ms，為了避免在程序中頻繁創(chuàng)建Conn對(duì)象，我們需要借助對(duì)象池管理Conn對(duì)象實(shí)例
*
* @author WangJun
* @version 1.0 15/10/28
* @since 1.6
*/
public class Conn {
/**
* 記錄對(duì)象的創(chuàng)建時(shí)間
*/
private long createTime;
/**
* 初始化Conn對(duì)象，模擬創(chuàng)建Conn對(duì)象平均消耗500ms
* @throws InterruptedException
*/
public Conn() throws InterruptedException {
Thread.sleep(500);
createTime = System.currentTimeMillis();
LoggerFactory.getLogger(getClass()).debug(" init conn suc... " + createTime);
}
/**
* 報(bào)告Conn對(duì)象信息
*/
public void report() {
LoggerFactory.getLogger(getClass()).info("this is a available conn " + createTime);
}
}
利用工廠模式，使對(duì)象池通過(guò)該工廠模式創(chuàng)建管理的對(duì)象
package com.peaceful.pool.demo;
import org.apache.commons.pool2.BasePooledObjectFactory;
import org.apache.commons.pool2.PooledObject;
import org.apache.commons.pool2.PooledObjectFactory;
import org.apache.commons.pool2.impl.DefaultPooledObject;
/**
* common-pool2 使用方式
*
* 為了使用common-pool2對(duì)象池管理，我們必須實(shí)現(xiàn){@link org.apache.commons.pool2.PooledObjectFactory}或者其子類
* 這是一個(gè)工廠模式，告訴對(duì)象池怎樣去創(chuàng)建要管理的對(duì)象
*
* BasePooledObjectFactory 是對(duì){@link org.apache.commons.pool2.PooledObjectFactory}的一個(gè)基本實(shí)現(xiàn)，我們可以繼承該類，減少一些方法的實(shí)現(xiàn)
*
* 在實(shí)現(xiàn){@link org.apache.commons.pool2.PooledObjectFactory}接口時(shí)，我們一定要實(shí)現(xiàn)的接口方法是{@link PooledObjectFactory#makeObject()}方法。
*
* @author WangJun
* @version 1.0 15/10/28
* @since 1.6
*/
public class ConnFactory extends BasePooledObjectFactory {
/**
* 間接實(shí)現(xiàn){@link PooledObjectFactory#makeObject()}方法，表明怎樣創(chuàng)建需要管理對(duì)象
*/
@Override
public Conn create() throws Exception {
return new Conn();
}
/**
* 在common-pool2中為了統(tǒng)計(jì)管理的對(duì)象的一些信息，比如調(diào)用次數(shù)，空閑時(shí)間，上次使用時(shí)間等，需要對(duì)管理的對(duì)象進(jìn)行包裝，然后在放入到對(duì)象池中
*
* @param obj 對(duì)象池要管理的對(duì)象
* @return 返回包裝后的PooledObject對(duì)象
*/
@Override
public PooledObject wrap(Conn obj) {
return new DefaultPooledObject(obj);
}
}
為了模擬的更真實(shí)，ConnPool池可以讓使用者個(gè)性化配置
package com.peaceful.pool.demo;
import org.apache.commons.pool2.impl.GenericObjectPoolConfig;
/**
* common-pool2 使用方式
*
* {@link org.apache.commons.pool2.impl.GenericObjectPool}支持個(gè)性化配置，我們可以配置對(duì)象池中總共的對(duì)象數(shù)，最大、最小空閑對(duì)象數(shù)等等
* 這邊繼承{@link GenericObjectPoolConfig}是為了ConnPool也可以進(jìn)行個(gè)性化的配置
*
* @author WangJun
* @version 1.0 15/10/28
* @since 1.6
*/
public class ConnPoolConfig extends GenericObjectPoolConfig {
public ConnPoolConfig() {
// defaults to make your life with connection pool easier :)
setMinIdle(5);
setTestOnBorrow(true);
}
}
有了創(chuàng)建對(duì)象的工廠，我們就可以創(chuàng)建一個(gè)對(duì)象池實(shí)例
package com.peaceful.pool.demo;
import org.apache.commons.pool2.impl.GenericObjectPool;
/**
* common-pool2 使用方式
*
* Conn對(duì)象管理池，這里利用GenericObjectPool作為對(duì)象池
*
* @author WangJun
* @version 1.0 15/10/28
* @since 1.6
*/
public class ConnPool extends GenericObjectPool {
/**
* 調(diào)用{@link GenericObjectPool}的構(gòu)造方法，構(gòu)造ConnPool
*/
public ConnPool() {
super(new ConnFactory(), new ConnPoolConfig());
}
/**
* 調(diào)用{@link GenericObjectPool}的構(gòu)造方法，構(gòu)造ConnPool
*/
public ConnPool(ConnPoolConfig connPoolConfig) {
super(new ConnFactory(), connPoolConfig);
}
}
這樣一個(gè)就完成了整個(gè)ConnPool的編碼，下面我們?cè)趯?xiě)一個(gè)demo，演示使用ConnPool
public class ConnDemo {
public static void main(String[] args) throws Exception {
ConnPoolConfig connPoolConfig = new ConnPoolConfig();
connPoolConfig.setMinIdle(5);
connPoolConfig.setMaxIdle(8);
ConnPool connPool = new ConnPool(connPoolConfig);
Conn conn1 = connPool.borrowObject();
Conn conn2 = connPool.borrowObject();
Conn conn3 = connPool.borrowObject();
Conn conn4 = connPool.borrowObject();
Conn conn5 = connPool.borrowObject();
conn1.report();
connPool.returnObject(conn1);
conn2.report();
connPool.returnObject(conn2);
conn3.report();
connPool.returnObject(conn3);
conn4.report();
connPool.returnObject(conn4);
conn5.report();
connPool.returnObject(conn5);
conn5.report();
// 被歸還的對(duì)象的引用，不可以在次歸還
// java.lang.IllegalStateException: Object has already been retured to this pool or is invalid
try {
connPool.returnObject(conn5);
}catch (Exception e){
e.printStackTrace();
}
}
}
下面是ConnDemo的運(yùn)行結(jié)果
[2015-10-28 14:56:06 DEBUG] {com.peaceful.pool.demo.Conn:18}- init conn suc...
[2015-10-28 14:56:07 DEBUG] {com.peaceful.pool.demo.Conn:18}- init conn suc...
[2015-10-28 14:56:07 DEBUG] {com.peaceful.pool.demo.Conn:18}- init conn suc...
[2015-10-28 14:56:08 DEBUG] {com.peaceful.pool.demo.Conn:18}- init conn suc...
[2015-10-28 14:56:08 DEBUG] {com.peaceful.pool.demo.Conn:18}- init conn suc...
[2015-10-28 14:56:08 INFO ] {com.peaceful.pool.demo.Conn:22}-this is a available conn 1446015366746
[2015-10-28 14:56:08 INFO ] {com.peaceful.pool.demo.Conn:22}-this is a available conn 1446015367346
[2015-10-28 14:56:08 INFO ] {com.peaceful.pool.demo.Conn:22}-this is a available conn 1446015367853
[2015-10-28 14:56:08 INFO ] {com.peaceful.pool.demo.Conn:22}-this is a available conn 1446015368354
[2015-10-28 14:56:08 INFO ] {com.peaceful.pool.demo.Conn:22}-this is a available conn 1446015368860
[2015-10-28 14:56:08 INFO ] {com.peaceful.pool.demo.Conn:22}-this is a available conn 1446015368860
java.lang.IllegalStateException: Object has already been retured to this pool or is invalid
at org.apache.commons.pool2.impl.GenericObjectPool.returnObject(GenericObjectPool.java:595)
at com.peaceful.pool.demo.ConnDemo.main(ConnDemo.java:37)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:140)
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