這篇實例中有四個類，分別為
CacheItem 緩存實體類
CachePool 緩存池
Student 學生實體類
MainTest 主測試類
其中，緩存實體類CacheItem 中存放管理學生實體對象Student ，緩存實體類CacheItem 存放在緩存池CachePool 中，MainTest 主要負責整體的測試工作。
緩存實體類
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package com.paic.zhangqi.cache; import java.util.Date; /** * 緩存實體 * @author ZHANGQI947 */public class CacheItem { // 創建緩存時間 private Date createTime = new Date(); // 緩存期滿時間 private long expireTime = 1; // 緩存實體 private Object entity; public CacheItem(Object obj, long expires) { this.entity = obj; this.expireTime = expires; } // 判斷緩存是否超時 public boolean isExpired() { return (expireTime != -1 && new Date().getTime() - createTime.getTime() > expireTime); } public Date getCreateTime() { return createTime; } public void setCreateTime(Date createTime) { this.createTime = createTime; } public Object getEntity() { return entity; } public void setEntity(Object entity) { this.entity = entity; } public long getExpireTime() { return expireTime; } public void setExpireTime(long expireTime) { this.expireTime = expireTime; } } |
緩存池CachePool
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package com.paic.zhangqi.cache; import java.util.Date; import java.util.HashMap; import java.util.Map; /** * 緩存池 * @author Administrator */public class CachePool { // 緩存池唯一實例 private static CachePool instance; // 緩存Map private static Map<String, Object> cacheItems; private CachePool() { cacheItems = new HashMap<String, Object>(); } /** * 獲取唯一的實例 * @return instance */ public synchronized static CachePool getInstance() { if (instance == null) { instance = new CachePool(); } return instance; } /** * 清除所有的Item緩存 */ public synchronized void clearAllItems() { cacheItems.clear(); } /** * 獲取緩存實例 * @param name 緩存名稱 * @return 緩存實例 */ public synchronized Object getCacheItem(String name) { if (!cacheItems.containsKey(name)) { return null; } CacheItem cacheItem = (CacheItem) cacheItems.get(name); if (cacheItem.isExpired()) { return null; } return cacheItem.getEntity(); } /** * 存放緩存信息 * @param name 名稱 * @param obj 實例對象 * @param expires 超時時長 */ public synchronized void putCacheItem(String name, Object obj, long expires) { // 判斷該對象是否在在緩存池，不在直接put if (!cacheItems.containsKey(name)) { cacheItems.put(name, new CacheItem(obj, expires)); } // 獲取緩存池中對象，更新對象信息 CacheItem cacheItem = (CacheItem) cacheItems.get(name); cacheItem.setCreateTime(new Date()); cacheItem.setEntity(obj); cacheItem.setExpireTime(expires); } /** * 移除緩存數據 * @param name */ public synchronized void removeCacheItem(String name) { if (!cacheItems.containsKey(name)) { return ; } cacheItems.remove(name); } /** * 獲取緩存數據的數量 * @return */ public int getSize() { return cacheItems.size(); } } |
學生類Student
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package com.paic.zhangqi.cache; /** * 學生類 * @author Administrator */public class Student { private String name; private String id; private int age; private int sal; public Student() { } public Student(String name, String id, int age, int sal) { this.name = name; this.id = id; this.age = age; this.sal = sal; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getId() { return id; } public void setId(String id) { this.id = id; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public int getSal() { return sal; } public void setSal(int sal) { this.sal = sal; } } |
主測試類MainTest
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package com.paic.zhangqi.cache; /** * 主測試類 * @author ZHANGQI947 */public class MainTest { /** * @param args * @throws InterruptedException */ public static void main(String[] args) throws InterruptedException { // 獲取緩存池 CachePool cachePool = CachePool.getInstance(); Student stu1 = new Student("l1", "stu001", 25, 40); Student stu2 = new Student("l2", "stu002", 25, 40); Student stu3 = new Student("l3", "stu003", 25, 40); Student stu4 = new Student("l4", "stu004", 25, 40); cachePool.putCacheItem("001", stu1, 122222); cachePool.putCacheItem("002", stu2, 10); cachePool.putCacheItem("003", stu3, 360002); cachePool.putCacheItem("004", stu4, 1222222); // 設置線程休眠，其中002對象會超時 Thread.sleep(200); Student stu001 = (Student) cachePool.getCacheItem("001"); if (null != stu001) { System.out.println(stu001.getName()); } // 由于超時，這里取出的002對象為null Student stu002 = (Student) cachePool.getCacheItem("002"); if (null != stu002) { System.out.println(stu002.getName()); } // 獲取打印緩存池中對象數量 int cacheSize = cachePool.getSize(); System.out.println(cacheSize); // 刪除對象002 cachePool.removeCacheItem("002"); // 打印緩存池數量 cacheSize = cachePool.getSize(); System.out.println(cacheSize); } } |
測試結果
l1
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3
希望本篇文章內容對您有所幫助
原文鏈接：http://blog.csdn.net/magi1201/article/details/60964107
