Java缓存池代码实例详解
这篇实例中有四个类，分别为
CacheItem 缓存实体类
CachePool 缓存池
Student 学生实体类
MainTest 主测试类
其中，缓存实体类CacheItem 中存放管理学生实体对象Student ，缓存实体类CacheItem 存放在缓存池CachePool 中，MainTest 主要负责整体的测试工作。
缓存实体类
packagecom.paic.zhangqi.cache;
importjava.util.Date;
/**
*缓存实体
*@authorZHANGQI947
*/
publicclassCacheItem{
//创建缓存时间
privateDatecreateTime=newDate();
//缓存期满时间
privatelongexpireTime=1;
//缓存实体
privateObjectentity;
publicCacheItem(Objectobj,longexpires){
this.entity=obj;
this.expireTime=expires;
}
//判断缓存是否超时
publicbooleanisExpired(){
return(expireTime!=-1&&newDate().getTime()-createTime.getTime()>expireTime);
}
publicDategetCreateTime(){
returncreateTime;
}
publicvoidsetCreateTime(DatecreateTime){
this.createTime=createTime;
}
publicObjectgetEntity(){
returnentity;
}
publicvoidsetEntity(Objectentity){
this.entity=entity;
}
publiclonggetExpireTime(){
returnexpireTime;
}
publicvoidsetExpireTime(longexpireTime){
this.expireTime=expireTime;
}
}
缓存池CachePool
packagecom.paic.zhangqi.cache;
importjava.util.Date;
importjava.util.HashMap;
importjava.util.Map;
/**
*缓存池
*@authorAdministrator
*/
publicclassCachePool{
//缓存池唯一实例
privatestaticCachePoolinstance;
//缓存Map
privatestaticMapcacheItems;
privateCachePool(){
cacheItems=newHashMap();
}
/**
*获取唯一的实例
*@returninstance
*/
publicsynchronizedstaticCachePoolgetInstance(){
if(instance==null){
instance=newCachePool();
}
returninstance;
}
/**
*清除所有的Item缓存
*/
publicsynchronizedvoidclearAllItems(){
cacheItems.clear();
}
/**
*获取缓存实例
*@paramname缓存名称
*@return缓存实例
*/
publicsynchronizedObjectgetCacheItem(Stringname){
if(!cacheItems.containsKey(name)){
returnnull;
}
CacheItemcacheItem=(CacheItem)cacheItems.get(name);
if(cacheItem.isExpired()){
returnnull;
}
returncacheItem.getEntity();
}
/**
*存放缓存信息
*@paramname名称
*@paramobj实例对象
*@paramexpires超时时长
*/
publicsynchronizedvoidputCacheItem(Stringname,Objectobj,longexpires){
//判断该对象是否在在缓存池，不在直接put
if(!cacheItems.containsKey(name)){
cacheItems.put(name,newCacheItem(obj,expires));
}
//获取缓存池中对象，更新对象信息
CacheItemcacheItem=(CacheItem)cacheItems.get(name);
cacheItem.setCreateTime(newDate());
cacheItem.setEntity(obj);
cacheItem.setExpireTime(expires);
}
/**
*移除缓存数据
*@paramname
*/
publicsynchronizedvoidremoveCacheItem(Stringname){
if(!cacheItems.containsKey(name)){
return;
}
cacheItems.remove(name);
}
/**
*获取缓存数据的数量
*@return
*/
publicintgetSize(){
returncacheItems.size();
}
}
学生类Student
packagecom.paic.zhangqi.cache;
/**
*学生类
*@authorAdministrator
*/
publicclassStudent{
privateStringname;
privateStringid;
privateintage;
privateintsal;
publicStudent(){
}
publicStudent(Stringname,Stringid,intage,intsal){
this.name=name;
this.id=id;
this.age=age;
this.sal=sal;
}
publicStringgetName(){
returnname;
}
publicvoidsetName(Stringname){
this.name=name;
}
publicStringgetId(){
returnid;
}
publicvoidsetId(Stringid){
this.id=id;
}
publicintgetAge(){
returnage;
}
publicvoidsetAge(intage){
this.age=age;
}
publicintgetSal(){
returnsal;
}
publicvoidsetSal(intsal){
this.sal=sal;
}
}
主测试类MainTest
packagecom.paic.zhangqi.cache;
/**
*主测试类
*@authorZHANGQI947
*/
publicclassMainTest{
/**
*@paramargs
*@throwsInterruptedException
*/
publicstaticvoidmain(String[]args)throwsInterruptedException{
//获取缓存池
CachePoolcachePool=CachePool.getInstance();
Studentstu1=newStudent("l1","stu001",25,40);
Studentstu2=newStudent("l2","stu002",25,40);
Studentstu3=newStudent("l3","stu003",25,40);
Studentstu4=newStudent("l4","stu004",25,40);
cachePool.putCacheItem("001",stu1,122222);
cachePool.putCacheItem("002",stu2,10);
cachePool.putCacheItem("003",stu3,360002);
cachePool.putCacheItem("004",stu4,1222222);
//设置线程休眠，其中002对象会超时
Thread.sleep(200);
Studentstu001=(Student)cachePool.getCacheItem("001");
if(null!=stu001){
System.out.println(stu001.getName());
}
//由于超时，这里取出的002对象为null
Studentstu002=(Student)cachePool.getCacheItem("002");
if(null!=stu002){
System.out.println(stu002.getName());
}
//获取打印缓存池中对象数量
intcacheSize=cachePool.getSize();
System.out.println(cacheSize);
//删除对象002
cachePool.removeCacheItem("002");
//打印缓存池数量
cacheSize=cachePool.getSize();
System.out.println(cacheSize);
}
}
测试结果
l1
4
3
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