代码结构

ColorDatabase.java

/* * All content copyright (c) Terracotta, Inc., except as may otherwise be noted in a separate copyright notice. All * rights reserved. */package org.terracotta;import java.awt.Color;import java.util.Map;import java.util.HashMap;/** * This class simulates an external color database that is used to populate the * ColorCache. The primary, named AWT colors are stored in a map. Anytime a * color is requested and found, the calling thread is put to sleep for 3 seconds * to simulate a slow or overloaded database. */public class ColorDatabase {  private static final Map
    
      colorMap = new HashMap
     
      ();  static {    colorMap.put("red", Color.red);    colorMap.put("blue", Color.blue);    colorMap.put("green", Color.green);    colorMap.put("white", Color.white);    colorMap.put("black", Color.black);    colorMap.put("lightGray", Color.lightGray);    colorMap.put("gray", Color.gray);    colorMap.put("darkGray", Color.darkGray);    colorMap.put("pink", Color.pink);    colorMap.put("orange", Color.orange);    colorMap.put("yellow", Color.yellow);    colorMap.put("magenta", Color.magenta);    colorMap.put("cyan", Color.cyan);  }  public ColorDatabase() {      }  /**   * Simulates retrieving expensive object from SOR.   */  public Color getColor(String name) {    Color color = colorMap.get(name);    if(color == null) {      return null;    }    try {      Thread.sleep(3000);    } catch(Exception e) {}    return color;  }}
     
    

ColorCache.java

/* * All content copyright (c) Terracotta, Inc., except as may otherwise be noted in a separate copyright notice. All * rights reserved. */package org.terracotta;import net.sf.ehcache.*;import java.awt.Color;import java.util.ArrayList;import java.util.Iterator;import java.util.List;public class ColorCache {  private static final CacheManager  cacheManager  = new CacheManager();  private static final ColorDatabase colorDatabase = new ColorDatabase();  public ColorCache() {    /**/  }  public Color getColor(String name) {    Element elem = getCache().get(name);    if (elem == null) {      Color color = colorDatabase.getColor(name);      if (color == null) { return null; }      getCache().put(elem = new Element(name, color));    }    return (Color) elem.getValue();  }  private Color getCachedColor(String name) {    Element elem = getCache().get(name);    return elem != null ? (Color) elem.getValue() : null;  }  public String[] getColorNames() {    @SuppressWarnings("unchecked")    Iterator
    
      keys = ((List
     
      ) getCache().getKeys()).iterator();    List
      
        list = new ArrayList
       
        ();    while (keys.hasNext()) {      String name = keys.next();      if (getCachedColor(name) != null) {        list.add(name);      }    }    return list.toArray(new String[list.size()]);  }  public long getTTL() {    return getCache().getCacheConfiguration().getTimeToLiveSeconds();  }  public long getTTI() {    return getCache().getCacheConfiguration().getTimeToIdleSeconds();  }  public int getSize() {    return getCache().getSize();  }  private Ehcache getCache() {    return cacheManager.getEhcache("colors");  }}
       
      
     
    

Test.java

package org.terracotta;import java.awt.Color;public class Test {	public static void main(String[] args) {		// TODO Auto-generated method stub		ColorCache cache = new ColorCache();				 long now = System.currentTimeMillis();		 Color red=cache.getColor("red");		 long elapsed = System.currentTimeMillis() - now;		 //第一次获取数据时间为：		 System.out.println("第一次获取数据时间为："+elapsed+"---"+red);		 		 long now2 = System.currentTimeMillis();		 Color red2=cache.getColor("red");		 long elapsed2 = System.currentTimeMillis() - now2;		 //第2次获取数据时间为：		 System.out.println("第2次获取数据时间为："+elapsed2+"---"+red2);		 	}}

第一次获取数据时间为：3003---java.awt.Color[r=255,g=0,b=0]