对象池模式和代理模式配合使用的例子

1、Connection接口

package com.xinye.test.pool3;

public interface Connection {
    void set(Object obj);
    void get();
}

2、Connection实现

package com.xinye.test.pool3;

public class ConnectionImpl implements Connection {

    @Override
    public void set(Object obj) {

    }

    @Override
    public void get() {

    }

}

3、Connection代理类

package com.xinye.test.pool3;
/**
 * 
 * @author xinye
 *
 */
public class ConnectionProxy implements Connection{
    private ReleaseablePoolItem<Connection> releaseable = null;
    public ConnectionProxy(ReleaseablePoolItem<Connection> rel){
        this.releaseable = rel;
    }
    @Override
    public void set(Object obj) {
        releaseable.getReference().set(obj);
    }

    @Override
    public void get() {
        releaseable.getReference().get();
    }

}

4、连接池

package com.xinye.test.pool3;

public class ConnectionPool {
    private static PoolManager<Connection> manager = new PoolManager<Connection>();
    private ConnectionPool(){
        
    }
    public static void add(int num){
        for(int i = 0;i < num;i++){
            manager.add(new ConnectionImpl());
        }
    } 
    public static Connection getConnection(){
         ReleaseablePoolItem<Connection> conn = manager.get();
         if(conn == null){
             return null;
         }
         return new ConnectionProxy(conn);
    }
    
}

5、池子中放的东西

package com.xinye.test.pool3;

public class PoolItem <T>{
    public boolean isUse = false;
    public T item;
    public PoolItem(T t){
        this.item = t;
    }
}

6、释放对象的时候不能再使用

package com.xinye.test.pool3;
/**
 * 
 * @author 
 *
 * @param <T>
 */
public class ReleaseablePoolItem <T>{
    public PoolItem<T> reference;
    public boolean released = false;
    public ReleaseablePoolItem(PoolItem<T> reference){
        
        this.reference = reference;
        
    }
    public T getReference(){
        if(released){
            throw new RuntimeException("Tried to use reference after it was released");
        }
        return reference.item;
    }
    public void release(){
        released = true;
        reference.isUse = false;
    }
}

7、池子管理对象

package com.xinye.test.pool3;

import java.util.ArrayList;

public class PoolManager <T> {
    private ArrayList<PoolItem<T>> list = new ArrayList<PoolItem<T>>();
    
    public void add(T t){
        list.add(new PoolItem<T>(t));
    }
    public ReleaseablePoolItem<T> get(){
        int len = list.size();
        for(int i = 0;i < len;i++){
            PoolItem<T> item = list.get(i);
            if(item.isUse == false){
                item.isUse = true;
                return new ReleaseablePoolItem<T>(item);
            }
        }
        return null;
    }
}