java带有效期的map_JAVA_编程开发_程序员俱乐部

package com.www.test;

import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

/**
* * * @Description: 带有效期map 简单实现 实现了基本的方法 * @author: zysnba * @date: 2018-10-19
* 下午5:08:46 * @param <K> * @param <V>
*/
public class ExpiryMap<K, V> extends HashMap<K, V> {
private static final long serialVersionUID = 1L;
/** * default expiry time 2m */
private long EXPIRY = 1000 * 60 * 2;
private HashMap<K, Long> expiryMap = new HashMap<>();

public ExpiryMap() {
super();
}

public ExpiryMap(long defaultExpiryTime) {
this(1 << 4, defaultExpiryTime);
}

public ExpiryMap(int initialCapacity, long defaultExpiryTime) {
super(initialCapacity);
this.EXPIRY = defaultExpiryTime;
}

public V put(K key, V value) {
expiryMap.put(key, System.currentTimeMillis() + EXPIRY);
return super.put(key, value);
}

public boolean containsKey(Object key) {
return !checkExpiry(key, true) && super.containsKey(key);
}

/** * @param key * @param value * @param expiryTime 键值对有效期 毫秒 * @return */
public V put(K key, V value, long expiryTime) {
expiryMap.put(key, System.currentTimeMillis() + expiryTime);
return super.put(key, value);
}

public int size() {
return entrySet().size();
}

public boolean isEmpty() {
return entrySet().size() == 0;
}

public boolean containsValue(Object value) {
if (value == null)
return Boolean.FALSE;
Set<java.util.Map.Entry<K, V>> set = super.entrySet();
Iterator<java.util.Map.Entry<K, V>> iterator = set.iterator();
while (iterator.hasNext()) {
java.util.Map.Entry<K, V> entry = iterator.next();
if (value.equals(entry.getValue())) {
if (checkExpiry(entry.getKey(), false)) {
iterator.remove();
return Boolean.FALSE;
} else
return Boolean.TRUE;
}
}
return Boolean.FALSE;
}

public Collection<V> values() {
Collection<V> values = super.values();
if (values == null || values.size() < 1)
return values;
Iterator<V> iterator = values.iterator();
while (iterator.hasNext()) {
V next = iterator.next();
if (!containsValue(next))
iterator.remove();
}
return values;
}

public V get(Object key) {
if (key == null)
return null;
if (checkExpiry(key, true))
return null;
return super.get(key);
}

/**
* * * @Description: 是否过期 * @param key * @return null:不存在或key为null -1:过期
* 存在且没过期返回value 因为过期的不是实时删除，所以稍微有点作用
*/
public Object isInvalid(Object key) {
if (key == null)
return null;
if (!expiryMap.containsKey(key)) {
return null;
}
long expiryTime = expiryMap.get(key);
boolean flag = System.currentTimeMillis() > expiryTime;
if (flag) {
super.remove(key);
expiryMap.remove(key);
return -1;
}
return super.get(key);
}

public void putAll(Map<? extends K, ? extends V> m) {
for (Map.Entry<? extends K, ? extends V> e : m.entrySet())
expiryMap.put(e.getKey(), System.currentTimeMillis() + EXPIRY);
super.putAll(m);
}

public Set<Map.Entry<K, V>> entrySet() {
Set<java.util.Map.Entry<K, V>> set = super.entrySet();
Iterator<java.util.Map.Entry<K, V>> iterator = set.iterator();
while (iterator.hasNext()) {
java.util.Map.Entry<K, V> entry = iterator.next();
if (checkExpiry(entry.getKey(), false))
iterator.remove();
}
return set;
}

/**
* * * @Description: 是否过期 * @author: zysnba * @date: 201８-10-19 下午5:05:02
* * @param expiryTime true 过期 * @param isRemoveSuper true super删除 * @return
*/
private boolean checkExpiry(Object key, boolean isRemoveSuper) {
if (!expiryMap.containsKey(key)) {
return Boolean.FALSE;
}
long expiryTime = expiryMap.get(key);
boolean flag = System.currentTimeMillis() > expiryTime;
if (flag) {
if (isRemoveSuper)
super.remove(key);
expiryMap.remove(key);
}
return flag;
}

public static void main(String[] args) throws InterruptedException {
// 5000毫秒数，默认两分钟
ExpiryMap<String, String> map = new ExpiryMap<>(5000);
map.put("test", "zysnba");
map.put("test1", "zysnba");
map.put("test2", "zysnba", 3000);// 三秒过期
Thread.sleep(4000);
System.out.println("isInvalid:" + map.isInvalid("test"));
System.out.println("size:" + map.size());
System.out.println("size:" + ((HashMap<String, String>) map).size());
Thread.sleep(3000);
for (Map.Entry<String, String> m : map.entrySet()) {
System.out.println("isInvalid:" + map.isInvalid(m.getKey()));
map.containsKey(m.getKey());
System.out.println("key:" + m.getKey() + " value:" + m.getValue());
}
System.out.println("test1" + map.get("test"));
}
}