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考虑到在使用HashMap在并发时会出现不正确行为,根据网上资料自己编写了采用ConcurrentHashMap来完成静态缓存的处理,目的是为了能够用来处理高并发的线程安全类,如有问题请各位大侠指教:
- package com.zengms.cache;
-
- import java.util.Map;
- import java.util.concurrent.ConcurrentHashMap;
-
- import org.apache.commons.logging.Log;
- import org.apache.commons.logging.LogFactory;
-
- public class MapCacheManager {
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- private final static Log log = LogFactory.getLog(MapCacheManager.class);
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- private volatile long updateTime = 0L;
-
- private volatile boolean updateFlag = true;
-
- private volatile static MapCacheManager mapCacheObject;
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- private static Map<String, String> cacheMap = new ConcurrentHashMap<String, String>();
-
- private MapCacheManager() {
- this.LoadCache();
- updateTime = System.currentTimeMillis();
-
- }
-
-
-
-
-
-
- public static MapCacheManager getInstance() {
- if (null == mapCacheObject) {
- synchronized (MapCacheManager.class) {
- if (null == mapCacheObject) {
- mapCacheObject = new MapCacheManager();
- }
- }
- }
- return mapCacheObject;
- }
-
-
-
-
- private void LoadCache() {
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- this.updateFlag = true;
-
-
- cacheMap.put("key1", "value1");
- cacheMap.put("key2", "value2");
- cacheMap.put("key3", "value3");
- cacheMap.put("key4", "value4");
- cacheMap.put("key5", "value5");
-
-
- this.updateFlag = false;
-
- }
-
-
-
-
-
-
- public Map<String, String> getMapCache() {
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- long currentTime = System.currentTimeMillis();
-
- if (this.updateFlag) {
- log.info("cache is Instance .....");
- return null;
-
- }
-
- if (this.IsTimeOut(currentTime)) {
- synchronized (this) {
- this.ReLoadCache();
- this.updateTime = currentTime;
- }
- }
-
- return this.cacheMap;
- }
-
- private boolean IsTimeOut(long currentTime) {
-
- return ((currentTime - this.updateTime) > 1000000);
- }
-
-
-
-
-
- private int getCacheSize() {
- return cacheMap.size();
- }
-
-
-
-
-
- private long getUpdateTime() {
- return this.updateTime;
- }
-
-
-
-
-
- private boolean getUpdateFlag() {
- return this.updateFlag;
- }
-
-
-
-
- private void ReLoadCache() {
- this.cacheMap.clear();
- this.LoadCache();
- }
-
- }
测试代码:
- package com.zengms.cache;
-
- import java.util.Iterator;
- import java.util.Map;
- import java.util.Set;
- import java.util.concurrent.ConcurrentHashMap;
-
- public class CacheTest {
-
- public static void main(String[] args) {
-
- MapCacheManager cache = MapCacheManager.getInstance();
- Map<String, String> cacheMap = new ConcurrentHashMap<String, String>();
-
- cacheMap = cache.getMapCache();
- Set<String> set = cacheMap.keySet();
- Iterator<String> it = set.iterator();
-
- while(it.hasNext()){
- String key = it.next();
- System.out.println(key+"="+cacheMap.get(key));
- }
- }
-
- }
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