举例讲解Java设计模式中的对象池模式编程

import java.util.Stack; 
 
@SuppressWarnings("unchecked") 
public class ObjectPool { 
 
  public ObjectPool() { 
  } 
 
  private PoolParam poolParam; 
 
  public void setPoolParam(PoolParam poolParam) { 
    this.poolParam = poolParam; 
  } 
 
  // 当前总对象个数 
  private int currentNum = 0; 
 
  private Class clazz; 
 
  public void setClazz(Class clazz) { 
    this.clazz = clazz; 
  } 
 
  // 栈，用来存放对象，模拟一个池 
  private Stack stack; 
 
  public Stack getStack() { 
    return stack; 
  } 
 
  public void setStack(Stack stack) { 
    this.stack = stack; 
  } 
 
  // ................................................................. 
  // 等待超时的记数变量 
  private int timeWait = 0; 
 
  // ................................................................. 
 
  // 创建对象池 
  public void initalPool(PoolParam poolParam, Class clazz) { 
 
    this.setPoolParam(poolParam); 
    this.setClazz(clazz); 
 
    stack = new Stack(); 
 
    stack.clear(); 
 
    // System.out.println("obj..pool is initial..."); 
    // 生成配置最小对象数，并压入栈中 
    try { 
 
      for (int i = 0; i < poolParam.getMinObjectCount(); i++) { 
 
        // 根据poolParam初始化对象池 
        stack.push(clazz.newInstance()); 
      } 
 
    } catch (InstantiationException e) { 
      e.printStackTrace(); 
    } catch (IllegalAccessException e) { 
      e.printStackTrace(); 
    } 
 
  } 
 
  // 创建单个对象 
  private Object createObj(Class clazz) { 
 
    Object obj = null; 
    try { 
 
      obj = clazz.newInstance(); 
 
      // System.out.println("a new one..."); 
    } catch (InstantiationException e) { 
      e.printStackTrace(); 
    } catch (IllegalAccessException e) { 
      e.printStackTrace(); 
    } 
 
    return obj; 
  } 
 
  // 对象池提供的get方法 
  public Object getInstance(){ 
 
    // System.out.println(stack.size()); 
 
    Object object = null; 
 
    if (stack.size() == 0) { 
 
      // 如果当前栈的长度为0，并且总的对象数没有超过定义最大数 
      if ((currentNum + poolParam.getMinObjectCount()) < poolParam 
          .getMaxObjectCount()) { 
 
        // 新创建一个对象 
        object = this.createObj(clazz); 
        // 对象数+1 
        currentNum++; 
 
      } else { 
 
        synchronized (this) { 
 
          try { 
            waitme(this); 
          } catch (Exception e) { 
            e.printStackTrace(); 
          } 
 
          // 获得通知后检测栈中是为空，并给出刚刚释放的资源 
          if (!stack.empty()) { 
            object = stack.pop(); 
          } 
        } 
      } 
 
    } else if (stack.size() > 0) { 
 
      object = stack.pop(); 
 
      // System.out.println(stack.size()); 
    } 
 
    return object; 
  } 
 
  // 返回对象的方法 
  public void returnObj(Object obj) { 
 
    if (clazz.isInstance(obj)) { 
 
      stack.push(obj); 
 
      synchronized (this) { 
 
        notify(); 
      } 
    } else { 
      System.out.println("this object can not push to stack!"); 
    } 
 
  } 
 
  // 等待递归算法 
  private void waitme(ObjectPool pool) { 
 
    // 等待2s的技术控制 
    if (timeWait >= 2000) { 
      System.out.println("jump up this step.."); 
 
      timeWait = 0; 
      return; 
 
    } else { 
 
      try { 
 
        pool.wait(500); 
 
        // 等待计数累加。。 
        timeWait +=1000; 
 
        System.out.println("waiting time to free obj.."); 
 
        if (stack.empty()) { 
          System.out.println("agian...."); 
          waitme(pool); 
        } 
 
      } catch (InterruptedException e) { 
        e.printStackTrace(); 
      } 
    } 
  } 
 
} 

@SuppressWarnings("unchecked") 
public class ObjectPoolManage { 
 
  private ObjectPoolManage() { 
  } 
 
  private static ObjectPool pool; 
   
 
 
  // 实现一个单例的获取方法....默认 
  public static synchronized ObjectPool getCacheObject(Class clazz) { 
 
    if (null != pool) { 
      return pool; 
    } else { 
 
      createObjectPool(null, clazz); 
      return pool; 
    } 
 
  } 
 
  // 实现一个单例的获取方法...自定义 
 
  public static synchronized ObjectPool getCacheObject(PoolParam p, Class clazz) { 
    if (null != pool) { 
      return pool; 
    } else { 
 
      createObjectPool(p, clazz); 
      return pool; 
    } 
 
  } 
 
  private static ObjectPool createObjectPool(PoolParam p, Class clazz) { 
 
    pool = new ObjectPool(); 
 
    if (null == p) { 
      pool.initalPool(new PoolParam(5,10), clazz); 
    } else { 
      pool.initalPool(p, clazz); 
    } 
 
    return pool; 
  } 
   
  private static Class getclazz(){ 
     
    Class clazz=null; 
     
    try { 
      clazz= Class.forName(ppp.getPropertyByName("objectPath")); 
    } catch (ClassNotFoundException e) { 
      e.printStackTrace(); 
    } 
     
    return clazz; 
  } 
}