1. 创建缓存实体类
保存需要缓存的数据，缓存创建的时间和缓存的有效期
/**
* 缓存类实体类
*/
public class CacheEntity<T> {
/**
* 要存储的数据
*/
private T value;
/**
* 创建的时间 单位ms
*/
private long createTime = System.currentTimeMillis();
/**
* 缓存的有效时间 单位ms （小于等于0表示永久保存）
*/
private long cacheTime;
public CacheEntity() {
super();
}
public CacheEntity(T value, long cacheTime) {
this.value = value;
this.cacheTime = cacheTime;
}
public T getValue() {
return value;
}
public void setValue(T value) {
this.value = value;
}
public long getCreateTime() {
return createTime;
}
public void setCreateTime(long createTime) {
this.createTime = createTime;
}
public long getCacheTime() {
return cacheTime;
}
public void setCacheTime(long cacheTime) {
this.cacheTime = cacheTime;
}
}
2. 缓存的管理类
主要用户管理缓存数据，对数据的添加，删除。对缓存数据有效性校验，其中创建了一个Timer定时任务，每分钟执行一次缓存清理。
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.TimeUnit;
/**
* 缓存管理器
*/
public class CacheManager {
/**
* 缓存Map对象
*/
private static ConcurrentHashMap<String,CacheEntity> cacheMap = new ConcurrentHashMap<>();
/**
* 创建定时任务每分钟清理一次缓存
*/
static{
Timer timer = new Timer();
timer.schedule(new TimerTask() {
@Override
public void run() {
refresh();
}
},0,60000);
}
/**
* 缓存刷新,清除过期数据
*/
public static void refresh(){
for (String key : cacheMap.keySet()) {
if(isExpire(key)){
remove(key);
}
}
}
/**
* 加入缓存
* @param key
* @param value
*/
public static boolean put(String key,Object value){
if(key.isEmpty()){
return false;
}
CacheEntity<Object> cacheEntity = new CacheEntity<>();
cacheEntity.setCacheTime(0);
cacheEntity.setValue(value);
cacheMap.put(key,cacheEntity);
return true;
}
/**
* 加入缓存，包含过期时间
* @param key 缓存数据的关键字
* @param value 缓存数据
* @param cacheTime 要缓存的时间
* @param timeUnit 时间单位
*/
public static boolean put(String key, Object value,long cacheTime,TimeUnit timeUnit){
if(key.isEmpty()){
return false;
}
CacheEntity<Object> cacheEntity = new CacheEntity<>();
cacheEntity.setCacheTime(timeUnit.toMillis(cacheTime));
cacheEntity.setValue(value);
cacheMap.put(key,cacheEntity);
return true;
}
/**
* 移除缓存数据
* @param key
*/
public static boolean remove(String key){
if(key.isEmpty()){
return false;
}
if(!cacheMap.containsKey(key)){
return true;
}
cacheMap.remove(key);
return true;
}
/**
* 获取缓存数据
* @param key
* @return
*/
public static Object get(String key){
if(key.isEmpty()||isExpire(key)){
return null;
}
CacheEntity cacheEntity = cacheMap.get(key);
if(null == cacheEntity){
return null;
}
return cacheEntity.getValue();
}
/**
* 判断当前数据是否已过期
* @param key
* @return
*/
private static boolean isExpire(String key){
if(key.isEmpty()){
return false;
}
if(cacheMap.containsKey(key)){
CacheEntity cacheEntity = cacheMap.get(key);
long createTime = cacheEntity.getCreateTime();
long currentTime = System.currentTimeMillis();
long cacheTime = cacheEntity.getCacheTime();
if(cacheTime>0&¤tTime-createTime>cacheTime){
return true;
}
return false;
}
return false;
}
/**
* 获取当前缓存大小（包含已过期但未清理的数据）
* @return
*/
public static int getCacheSize(){
return cacheMap.size();
}
}
3. 缓存的测试类
验证缓存对数据的存储，提取及对数据有效性的验证。
import java.util.concurrent.TimeUnit;
/**
* 测试类
*/
public class Main {
public static void main(String[] args) throws InterruptedException {
// try {
// Class.forName(CacheManager.class.getName());
// } catch (ClassNotFoundException e) {
// e.printStackTrace();
// }
CacheManager.put("one","第一个数据");
CacheManager.put("two","第二条数据",50, TimeUnit.SECONDS);
CacheManager.put("three","第三条数据",3,TimeUnit.MINUTES);
System.out.println("立刻获取------------------------");
System.out.println(CacheManager.get("one"));
System.out.println(CacheManager.get("two"));
System.out.println(CacheManager.get("three"));
Thread.sleep(55000);
System.out.println("55秒后------------------------");
System.out.println(CacheManager.get("one"));
System.out.println(CacheManager.get("two"));
System.out.println(CacheManager.get("three"));
Thread.sleep(60000-55000);
System.out.println("1分钟后------------------------");
System.out.println(CacheManager.get("one"));
System.out.println(CacheManager.get("two"));
System.out.println(CacheManager.get("three"));
Thread.sleep(120000-60000);
System.out.println("2分钟后------------------------");
System.out.println(CacheManager.get("one"));
System.out.println(CacheManager.get("two"));
System.out.println(CacheManager.get("three"));
Thread.sleep(180000-120000);
System.out.println("3分钟时------------------------");
System.out.println(CacheManager.get("one"));
System.out.println(CacheManager.get("two"));
System.out.println(CacheManager.get("three"));
Thread.sleep(190000-180000);
System.out.println("3分钟10秒后------------------------");
System.out.println(CacheManager.get("one"));
System.out.println(CacheManager.get("two"));
System.out.println(CacheManager.get("three"));
System.out.println("缓存的大小: "+CacheManager.getCacheSize());
System.out.println("main over------------------------");
}
}
4.测试结果
