Registry的用途

先贴上源代码：

/*
 * Ext GWT - Ext for GWT
 * Copyright(c) 2007-2009, Ext JS, LLC.
 * [e-mail]
 * 
 * http://extjs.com/license
 */
package com.extjs.gxt.ui.client;

import java.util.Map;

import com.extjs.gxt.ui.client.core.FastMap;
import com.extjs.gxt.ui.client.event.BaseObservable;

/**
 * A local storage of objects stored by id.
 */
public final class Registry extends BaseObservable {

  protected static Map<String, Object> map = new FastMap<Object>();

  /**
   * Returns the object with the given id.
   * 
   * @param id the identifier
   * @return the object or <code>null</code> if no match
   */
  @SuppressWarnings("unchecked")
  public static <X> X get(String id) {
    return (X) map.get(id);
  }

  /**
   * Returns a map of all registered objects.
   * 
   * @return the object map
   */
  public static Map<String, Object> getAll() {
    return map;
  }

  /**
   * Registers an object.
   * 
   * @param id the identifier
   * @param obj the object to be registered
   */
  public static void register(String id, Object obj) {
    map.put(id, obj);
  }

  /**
   * Unregisters an object.
   * 
   * @param id the identifier
   */
  public static void unregister(String id) {
    map.remove(id);
  }

  /**
   * Unregisters all registered objects.
   */
  public static void unregisterAll() {
    map.clear();
  }

  private Registry() {
  }

}

Registry类的用途就是存储全局变量。
他里面的方法全部是静态的。
如果要放置一个对象进去，可以这样

Registry.register("id", Object obj)

如果要取出来，则

Registry.get("id");