一个FTP Pool工具类的实现(Commons Pool)

糜3392

　　今天写了一个FTPPool，贴上来分享一下。
　　使用了相关的开源工具包2个：commons-net-3.0.1.jar和commons-pool-1.6.jar。
　　代码如下：
　　Pool.java：使用GenericObjectPool作为连接池管理连接，简单封装了borrowObject，returnObject。

public abstract class Pool<T> {
private final GenericObjectPool<T> internalPool;
public Pool(GenericObjectPool.Config poolConfig, PoolableObjectFactory factory)  
{
this.internalPool = new GenericObjectPool<T>(factory, poolConfig);  
}
public T getResource(){
try{
return this.internalPool.borrowObject();
}catch(Exception e){
e.printStackTrace();
return null;
}
}
public void returnResource(T resource){
try {
this.internalPool.returnObject(resource);
}catch (Exception e) {
e.printStackTrace();
}
}
public void destroy(){
try{
this.internalPool.close();  
}catch (Exception e) {
e.printStackTrace();
}
}
public int inPoolSize(){
try{
return this.internalPool.getNumIdle();
}catch(Exception e){
e.printStackTrace();
return 0;
}
}
public int borrowSize(){
try{
return this.internalPool.getNumActive();
}catch(Exception e){
e.printStackTrace();
return 0;
}
}
}
　　FTPPool.java：继承了抽象类Pool，在构造方法中实例化FTPPoolableObjectFactory，以处理GenericObjectPool中的操作。

public class FTPPool extends Pool<FTPClient>{
public FTPPool(Config poolConfig,String host,int port,String user,String password,String passiveModeConf){
super(poolConfig, new FTPPoolableObjectFactory(host, port, user, password, passiveModeConf));
}
}
　　FTPPoolableObjectFactory.java：继承BasePoolableObjectFactory，其中的方法分别为：
　　GenericObjectPool内部会回调makeObject创建对象。
　　GenericObjectPool内部会回调destroyObject销毁对象。
　　GenericObjectPool内部会回调validateObject检验对象。

public class FTPPoolableObjectFactory extends BasePoolableObjectFactory{
private String host;
private int port;
private String user;
private String password;
private String passiveModeConf;
public FTPPoolableObjectFactory(String host,int port,String user,String password,String passiveModeConf){
this.host = host;
System.out.println("host:"+host);
this.port = port;
System.out.println("port:"+port);
this.user = user;
System.out.println("user:"+user);
this.password = password;
System.out.println("password:"+password);
this.passiveModeConf = passiveModeConf;
System.out.println("passiveModeConf:"+passiveModeConf);
}
@Override
public Object makeObject() throws Exception {
FTPClient ftpClient = new FTPClient();
ftpClient.connect(host, port);
ftpClient.setControlKeepAliveTimeout(300);//set timeout to 5 minutes
ftpClient.login(user, password);
boolean passiveMode = false;
if (passiveModeConf == null || Boolean.parseBoolean(passiveModeConf) == true){
passiveMode = true;
}
if (passiveMode) {
ftpClient.enterLocalPassiveMode();
}
ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
return ftpClient;
}
@Override
public void destroyObject(Object obj) throws Exception {
if(obj instanceof FTPClient){
FTPClient ftpClient=(FTPClient)obj;
if(!ftpClient.isConnected()) return ;
try{
ftpClient.disconnect();
}catch(Exception e){
e.printStackTrace();
}
}
}
@Override
public boolean validateObject(Object obj) {
if(obj instanceof FTPClient){
FTPClient ftpClient=(FTPClient)obj;
try{
return ftpClient.isConnected();
}catch(Exception e){
return false;
}
}
return false;
}
}
　　最后是使用方法：

public static void main(String[] args) throws Exception{
GenericObjectPool.Config config = new Config();
//最大池容量
config.maxActive=5;
//从池中取对象达到最大时,继续创建新对象.
config.whenExhaustedAction = GenericObjectPool.WHEN_EXHAUSTED_GROW;
//池为空时取对象等待的最大毫秒数.
config.maxWait=60*1000;
//取出对象时验证(此处设置成验证ftp是否处于连接状态).
config.testOnBorrow=true;
//还回对象时验证(此处设置成验证ftp是否处于连接状态).
config.testOnReturn=true;
FTPPool pool = new FTPPool(config,"XXXXXX",21,"xxxxxx","xxxxxx","true");
System.out.println("borrowSize1:"+pool.borrowSize());
System.out.println("inPoolSize1:"+pool.inPoolSize());
long begin=System.currentTimeMillis();
for(int i=0;i<8;i++){
FTPClient ftpClient = pool.getResource();
System.out.println("ftpClient"+(i+1)+" isConnected:"+ftpClient.isConnected());
//ftpClient.disconnect();
//pool.returnResource(ftpClient);
pool.returnResource(ftpClient);
}
System.out.println("time:"+(System.currentTimeMillis()-begin));
System.out.println("borrowSize2:"+pool.borrowSize());
System.out.println("inPoolSize2:"+pool.inPoolSize());
pool.destroy();
}
　　
    其中testOnBorrow、testOnReturn设置为true时，会在回调中调用validateObject方法进行对象检验。 pool.getResource()方法会从池中取出对象，pool.returnResource()方法会向池中还回对象。具体API含义请参见commons-pool的文档。

　　以上就是一个简单的FTPPool的实现，commons-pool除了GenericObjectPool外还提供了不同的池。感觉有了这个开源工具随便写个连接池都方便很多了，所以一定要好好研究下。另外希望本文对看到的人有所帮助。
　　(PS:这段代码其实是参考了开源工具jedis-pool的源代码而写成，看来看开源代码对编程能力有很大提升。另外，今天要happy birthday!)