经救援后,Xander依然距离了人间,他的爹妈协商后调节把男女的五脏六腑捐给更亟待的人。

Intent

  • Object pooling can offer a significant performance boost; it is most
    effective in situations where the cost of initializing a class
    instance is high, the rate of instantiation of a class is high, and
    the number of instantiations in use at any one time is low.

Beside the pool, there are a variety of

But after becoming exhausted, Xander slipped to the bottom of the pool,
lapsed into a coma and was eventually taken to Cook Children’s Medical
Center

Java Sample

// ObjectPool Class

public abstract class ObjectPool<T> {
  private long expirationTime;

  private Hashtable<T, Long> locked, unlocked;

  public ObjectPool() {
    expirationTime = 30000; // 30 seconds
    locked = new Hashtable<T, Long>();
    unlocked = new Hashtable<T, Long>();
  }

  protected abstract T create();

  public abstract boolean validate(T o);

  public abstract void expire(T o);

  public synchronized T checkOut() {
    long now = System.currentTimeMillis();
    T t;
    if (unlocked.size() > 0) {
      Enumeration<T> e = unlocked.keys();
      while (e.hasMoreElements()) {
        t = e.nextElement();
        if ((now - unlocked.get(t)) > expirationTime) {
          // object has expired
          unlocked.remove(t);
          expire(t);
          t = null;
        } else {
          if (validate(t)) {
            unlocked.remove(t);
            locked.put(t, now);
            return (t);
          } else {
            // object failed validation
            unlocked.remove(t);
            expire(t);
            t = null;
          }
        }
      }
    }
    // no objects available, create a new one
    t = create();
    locked.put(t, now);
    return (t);
  }

  public synchronized void checkIn(T t) {
    locked.remove(t);
    unlocked.put(t, System.currentTimeMillis());
  }
}

//The three remaining methods are abstract 
//and therefore must be implemented by the subclass

public class JDBCConnectionPool extends ObjectPool<Connection> {

  private String dsn, usr, pwd;

  public JDBCConnectionPool(String driver, String dsn, String usr, String pwd) {
    super();
    try {
      Class.forName(driver).newInstance();
    } catch (Exception e) {
      e.printStackTrace();
    }
    this.dsn = dsn;
    this.usr = usr;
    this.pwd = pwd;
  }

  @Override
  protected Connection create() {
    try {
      return (DriverManager.getConnection(dsn, usr, pwd));
    } catch (SQLException e) {
      e.printStackTrace();
      return (null);
    }
  }

  @Override
  public void expire(Connection o) {
    try {
      ((Connection) o).close();
    } catch (SQLException e) {
      e.printStackTrace();
    }
  }

  @Override
  public boolean validate(Connection o) {
    try {
      return (!((Connection) o).isClosed());
    } catch (SQLException e) {
      e.printStackTrace();
      return (false);
    }
  }
}

JDBCConnectionPool will allow the application to borrow and return
database connections:

public class Main {
  public static void main(String args[]) {
    // Do something...
    ...

    // Create the ConnectionPool:
    JDBCConnectionPool pool = new JDBCConnectionPool(
      "org.hsqldb.jdbcDriver", "jdbc:hsqldb://localhost/mydb",
      "sa", "secret");

    // Get a connection:
    Connection con = pool.checkOut();
    // Use the connection
    ...
    // Return the connection:
    pool.checkIn(con);

  }
}

pool, we could have a bird’s eye view of the city, so that’s one of the
selling points, even if you don’t know how to swim, you could also have
a good timethere.

When Xander Vento saw a 3-year-old girl struggling in the deep end of a
Fort Worth, Texas pool Monday, he held her head up so that she could
stay above water

Discussion

  • The Object Pool lets others “check out” objects from its pool, when
    those objects are no longer needed by their processes, they are
    returned to the pool in order to be reused.
  • However, we don’t want a process to have to wait for a particular
    object to be released, so the Object Pool also instantiates new
    objects as they are required, but must also implement a facility to
    clean up unused objects periodically.

Oh, and I meant to say earlier, from the swimming

不久前,一名南卡罗来纳州的四岁男童Xander在见到一名三周岁小女孩落水之后,下到水中施救,可是最终,小女孩得救了,Xander却因为过度辛劳而沉入水底。

Structure

The general idea for the Connection Pool pattern is that if instances of
a class can be reused, you avoid creating instances of the class by
reusing them.

yzc888亚洲城手机版 1

  • <strong>Reusable</strong> – Instances of classes in this role
    collaborate with other objects for a limited amount of time, then
    they are no longer needed for that collaboration.
  • <strong>Client</strong> – Instances of classes in this role use
    Reusable objects.
  • <strong>ReusablePool</strong> – Instances of classes in this role
    manage Reusable objects for use by Client objects.

Usually, it is desirable to keep all Reusable objects that are not
currently in use in the same object pool so that they can be managed by
one coherent policy. To achieve this, the ReusablePool class is
designed to be a singleton class. Its constructor(s) are private, which
forces other classes to call its getInstance method to get the one
instance of the ReusablePool class.

A Client object calls a ReusablePool object’s acquireReusable method
when it needs a Reusable object. A ReusablePool object maintains a
collection of Reusable objects. It uses the collection of Reusable
objects to contain a pool of Reusable objects that are not currently
in use.

If there are any Reusable objects in the pool when the
acquireReusable method is called, it removes a Reusable object from
the pool and returns it. If the pool is empty, then the
acquireReusable method creates a Reusable object if it can. If the
acquireReusable method cannot create a new Reusable object, then it
waits until a Reusable object is returned to the collection.

yzc888亚洲城手机版:美国4岁男孩为救落水女孩英勇牺牲,8月雅思口语Part2话题预测及范文。Client objects pass a Reusable object to a ReusablePool object’s
releaseReusable method when they are finished with the object. The
releaseReusable method returns a Reusable object to the pool of
Reusable objects that are not in use.

In many applications of the Object Pool pattern, there are reasons for
limiting the total number of Reusable objects that may exist. In such
cases, the ReusablePool object that creates Reusable objects is
responsible for not creating more than a specified maximum number of
Reusable objects. If ReusablePool objects are responsible for
limiting the number of objects they will create, then the ReusablePool
class will have a method for specifying the maximum number of objects to
be created. That method is indicated in the above diagram as
setMaxPoolSize.

example, when I’m

Xander’s parents have decided to donate their son’s organs and friends
of the family have set up a fund to help them pay for their medical
expenses and other needs. They hope to raise $20,000.

Rules of thumb

  • The Factory Method pattern can be used to encapsulate the creation
    logic for objects. However, it does not manage them after their
    creation, the object pool pattern keeps track of the objects it
    creates.
  • Object Pools are usually implemented as Singletons.

entertainment/recreation facilities, like water jet, floating balls and
all

(沪江匈牙利(Magyarország)语)

Check list

  1. Create ObjectPool class with private array of Objects inside
  2. Create acquare and release methods in ObjectPool class
  3. Make sure that your ObjectPool is Singleton

basically sets the main tone of the building. When it’s getting dark,
the whole building looks like apiece of art from a distance, you know,
full of lights which illuminate thewhole area.

Example

Do you like bowling? If you do, you probably know that you should change
your shoes when you getting the bowling club. Shoe shelf is wonderful
example of Object Pool. Once you want to play, you’ll get your pair
(aquireReusable) from it. After the game, you’ll return shoes back to
the shelf (releaseReusable).

yzc888亚洲城手机版 2

out it, I mean, it gives me a chance to experience something different.
For

Problem

  • Object pools (otherwise known as resource pools) are used to manage
    the object caching. A client with access to a Object pool can avoid
    creating a new Objects by simply asking the pool for one that has
    already been instantiated instead. Generally the pool will be a
    growing pool, i.e. the pool itself will create new objects if the
    pool is empty, or we can have a pool, which restricts the number of
    objects created.
  • It is desirable to keep all Reusable objects that are not currently
    in use in the same object pool so that they can be managed by one
    coherent policy. To achieve this, the Reusable Pool class is
    designed to be a singleton class.

building is the water park on the top floor, which has made it a magnet
for the

locals, especially for kids and young adults. It has an Olympic-size
swimming

It’s a 10-floor building with various facilities, so it’s the most
popular hangout for people of all agegroups in that area.

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