Java 中常用缓存Cache机制的实现

所谓缓存，就是将程序或系统经常要调用的对象存在内存中，一遍其使用时可以快速调用，不必再去创建新的重复的实例。这样做可以减少系统开销，提高系统效率。

所谓缓存，就是将程序或系统经常要调用的对象存在内存中，一遍其使用时可以快速调用，不必再去创建新的重复的实例。这样做可以减少系统开销，提高系统效率。

缓存主要可分为二大类: 

一、通过文件缓存,顾名思义文件缓存是指把数据存储在磁盘上，不管你是以XML格式，序列化文件DAT格式还是其它文件格式；  

二、内存缓存，也就是实现一个类中静态Map,对这个Map进行常规的增删查. 

代码如下：

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package lhm.hcy.guge.frameset.cache;    import java.util.*;     //Description: 管理缓存     //可扩展的功能：当chche到内存溢出时必须清除掉最早期的一些缓存对象，这就要求对每个缓存对象保存创建时间    public class CacheManager {     private static HashMap cacheMap = new HashMap();        //单实例构造方法     private CacheManager() {         super();     }     //获取布尔值的缓存     public static boolean getSimpleFlag(String key){         try{             return (Boolean) cacheMap.get(key);         }catch(NullPointerException e){             return false;         }     }     public static long getServerStartdt(String key){         try {             return (Long)cacheMap.get(key);         } catch (Exception ex) {             return 0;         }     }     //设置布尔值的缓存     public synchronized static boolean setSimpleFlag(String key,boolean flag){         if (flag && getSimpleFlag(key)) {//假如为真不允许被覆盖             return false;         }else{             cacheMap.put(key, flag);             return true;         }     }     public synchronized static boolean setSimpleFlag(String key,long serverbegrundt){         if (cacheMap.get(key) == null) {             cacheMap.put(key,serverbegrundt);             return true;         }else{             return false;         }     }           //得到缓存。同步静态方法     private synchronized static Cache getCache(String key) {         return (Cache) cacheMap.get(key);     }        //判断是否存在一个缓存     private synchronized static boolean hasCache(String key) {         return cacheMap.containsKey(key);     }        //清除所有缓存     public synchronized static void clearAll() {         cacheMap.clear();     }        //清除某一类特定缓存,通过遍历HASHMAP下的所有对象，来判断它的KEY与传入的TYPE是否匹配     public synchronized static void clearAll(String type) {         Iterator i = cacheMap.entrySet().iterator();         String key;         ArrayList arr = new ArrayList();         try {             while (i.hasNext()) {                 java.util.Map.Entry entry = (java.util.Map.Entry) i.next();                 key = (String) entry.getKey();                 if (key.startsWith(type)) { //如果匹配则删除掉                     arr.add(key);                 }             }             for (int k = 0; k < arr.size(); k++) {                 clearOnly(arr.get(k));             }         } catch (Exception ex) {             ex.printStackTrace();         }     }        //清除指定的缓存     public synchronized static void clearOnly(String key) {         cacheMap.remove(key);     }        //载入缓存     public synchronized static void putCache(String key, Cache obj) {         cacheMap.put(key, obj);     }        //获取缓存信息     public static Cache getCacheInfo(String key) {            if (hasCache(key)) {             Cache cache = getCache(key);             if (cacheExpired(cache)) { //调用判断是否终止方法                 cache.setExpired(true);             }             return cache;         }else             return null;     }        //载入缓存信息     public static void putCacheInfo(String key, Cache obj, long dt,boolean expired) {         Cache cache = new Cache();         cache.setKey(key);         cache.setTimeOut(dt + System.currentTimeMillis()); //设置多久后更新缓存         cache.setValue(obj);         cache.setExpired(expired); //缓存默认载入时，终止状态为FALSE         cacheMap.put(key, cache);     }     //重写载入缓存信息方法     public static void putCacheInfo(String key,Cache obj,long dt){         Cache cache = new Cache();         cache.setKey(key);         cache.setTimeOut(dt+System.currentTimeMillis());         cache.setValue(obj);         cache.setExpired(false);         cacheMap.put(key,cache);     }        //判断缓存是否终止     public static boolean cacheExpired(Cache cache) {         if (null == cache) { //传入的缓存不存在             return false;         }         long nowDt = System.currentTimeMillis(); //系统当前的毫秒数         long cacheDt = cache.getTimeOut(); //缓存内的过期毫秒数         if (cacheDt <= 0||cacheDt>nowDt) { //过期时间小于等于零时,或者过期时间大于当前时间时，则为FALSE             return false;         } else { //大于过期时间 即过期             return true;         }     }        //获取缓存中的大小     public static int getCacheSize() {         return cacheMap.size();     }        //获取指定的类型的大小     public static int getCacheSize(String type) {         int k = 0;         Iterator i = cacheMap.entrySet().iterator();         String key;         try {             while (i.hasNext()) {                 java.util.Map.Entry entry = (java.util.Map.Entry) i.next();                 key = (String) entry.getKey();                 if (key.indexOf(type) != -1) { //如果匹配则删除掉                     k++;                 }             }         } catch (Exception ex) {             ex.printStackTrace();         }            return k;     }        //获取缓存对象中的所有键值名称     public static ArrayList getCacheAllkey() {         ArrayList a = new ArrayList();         try {             Iterator i = cacheMap.entrySet().iterator();             while (i.hasNext()) {                 java.util.Map.Entry entry = (java.util.Map.Entry) i.next();                 a.add((String) entry.getKey());             }         } catch (Exception ex) {} finally {             return a;         }     }        //获取缓存对象中指定类型 的键值名称     public static ArrayList getCacheListkey(String type) {         ArrayList a = new ArrayList();         String key;         try {             Iterator i = cacheMap.entrySet().iterator();             while (i.hasNext()) {                 java.util.Map.Entry entry = (java.util.Map.Entry) i.next();                 key = (String) entry.getKey();                 if (key.indexOf(type) != -1) {                     a.add(key);                 }             }         } catch (Exception ex) {} finally {             return a;         }     }    }       package lhm.hcy.guge.frameset.cache;    public class Cache {         private String key;//缓存ID         private Object value;//缓存数据         private long timeOut;//更新时间         private boolean expired; //是否终止         public Cache() {                 super();         }            public Cache(String key, Object value, long timeOut, boolean expired) {                 this.key = key;                 this.value = value;                 this.timeOut = timeOut;                 this.expired = expired;         }            public String getKey() {                 return key;         }            public long getTimeOut() {                 return timeOut;         }            public Object getValue() {                 return value;         }            public void setKey(String string) {                 key = string;         }            public void setTimeOut(long l) {                 timeOut = l;         }            public void setValue(Object object) {                 value = object;         }            public boolean isExpired() {                 return expired;         }            public void setExpired(boolean b) {                 expired = b;         } }    //测试类， class Test {     public static void main(String[] args) {         System.out.println(CacheManager.getSimpleFlag("alksd")); //        CacheManager.putCache("abc", new Cache()); //        CacheManager.putCache("def", new Cache()); //        CacheManager.putCache("ccc", new Cache()); //        CacheManager.clearOnly(""); //        Cache c = new Cache(); //        for (int i = 0; i < 10; i++) { //            CacheManager.putCache("" + i, c); //        } //        CacheManager.putCache("aaaaaaaa", c); //        CacheManager.putCache("abchcy;alskd", c); //        CacheManager.putCache("cccccccc", c); //        CacheManager.putCache("abcoqiwhcy", c); //        System.out.println("删除前的大小："+CacheManager.getCacheSize()); //        CacheManager.getCacheAllkey(); //        CacheManager.clearAll("aaaa"); //        System.out.println("删除后的大小："+CacheManager.getCacheSize()); //        CacheManager.getCacheAllkey();           } }

spring中的redis service实现

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package com.eshore.ismp.cache.redis;   import java.io.UnsupportedEncodingException; import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.HashSet; import java.util.List; import java.util.Map; import java.util.Map.Entry; import java.util.Set;   import org.springframework.beans.factory.annotation.Autowired; import org.springframework.dao.DataAccessException; import org.springframework.data.redis.connection.RedisConnection; import org.springframework.data.redis.core.RedisCallback; import org.springframework.data.redis.core.RedisTemplate; import org.springframework.stereotype.Service;   @Service public class RedisService {       private static String redisCode = "utf-8";           @Autowired     private RedisTemplate<String, String> redisTemplate;       /**      * 从指定的列表右边出队,添加到目的列表中      *      * @param srckey      *            源列表      * @param dstkey      *            　目的列表      * @return      */     public String rpoppush(final String srckey, final String dstkey) {         return redisTemplate.execute(new RedisCallback<String>() {             public String doInRedis(RedisConnection connection)                     throws DataAccessException {                 try {                     return new String (connection.rPopLPush(srckey.getBytes(), dstkey.getBytes()), redisCode);                 } catch (UnsupportedEncodingException e) {                     e.printStackTrace();                 }                 return "";             }         });     }     /**      * 获取指定列表的范围数据      *      * @param key      *            　列表名      * @param start      *            　开始位置      * @param end      *            　结束位置      * @return      */     public List<String> lrange(final String key, final int start, final int end) {         return redisTemplate.execute(new RedisCallback<List<String>>() {             List<String> result = new ArrayList<String>();             public List<String> doInRedis(RedisConnection connection)                     throws DataAccessException {                 List<byte[]> bytelist= connection.lRange(key.getBytes(), start, end);                 for (byte[] b : bytelist) {                     try {                         result.add(new String(b, redisCode));                     } catch (UnsupportedEncodingException e) {                         e.printStackTrace();                     }                 }                 return result;             }         });     }     /**      * 从队列的左边取出一条数据      *      * @param key      *            　列表名      * @return      */     public String lpop(final String key) {         return redisTemplate.execute(new RedisCallback<String>() {             public String doInRedis(RedisConnection connection)                     throws DataAccessException {                 byte[] result = connection.lPop(key.getBytes());                 if (result != null) {                     try {                         return new String (result , redisCode);                     } catch (UnsupportedEncodingException e) {                         e.printStackTrace();                     }                 }                 return "";             }         });     }           /**      * 从队列的左边取出一条数据      *      * @param key      *            　列表名      * @return      */     public List<?> lpop(final String key,final int size) {         List<Object> list =  redisTemplate.executePipelined(new RedisCallback<List<Object>>() {             public List<Object> doInRedis(RedisConnection connection)                     throws DataAccessException {                 byte[] keyBytes = key.getBytes();                 for(int i =0 ; i< size; i++){                     connection.lPop(keyBytes);                 }                 return null;             }         });         list.removeAll(Collections.singleton(null));         return list;     }           /**      * 从列表右边添加数据      *      * @param key      *            列表名      * @param values      *            数据      * @return      */     public long rpush(final String key, final String... values) {         return redisTemplate.execute(new RedisCallback<Long>() {             public Long doInRedis(RedisConnection connection)                     throws DataAccessException {                 long result = 0;                 for (String v : values) {                     result = connection.rPush(key.getBytes(), v.getBytes());                 }                 return result;             }         });     }           /**      * 从列表右边添加数据      *      * @param key      *            列表名      * @param values      *            数据      * @return      */     public long rpush(final String key, final Collection<String> values) {         return redisTemplate.opsForList().rightPushAll(key, values);     }           public int hmset(final String key, final Map<String,String> values) {         try{          redisTemplate.opsForHash().putAll(key, values);         }catch(Exception e){             e.printStackTrace();             return -1;         }         return 0 ;     }     public String hget(final String key, final String field){         Object obj =redisTemplate.opsForHash().get(key, field);         return String.valueOf(obj);     }           public List<?> hkeys(final String key){         return redisTemplate.execute(new RedisCallback<List<Object>>(){             List<Object> list = new ArrayList<Object>();             public List<Object> doInRedis(RedisConnection connection)                     throws DataAccessException {                 Set<byte[]> sets=connection.hKeys(key.getBytes());                 if(!sets.isEmpty()){                     for(byte[] b : sets){                         list.add(redisTemplate.getValueSerializer().deserialize(b).toString());                     }                     return list;                 }                 return null;             }         });     }           /**      * 删除hash表中field      */     public void hdel(final String key,final String field){         redisTemplate.opsForHash().delete(key, field);     }     /**      * 从列表右边添加数据,并且设置列表的存活时间      *      * @param key      *            列表名      * @param liveTime      *            存活时间(单位 秒)      * @param values      *            数据      * @return      */     public long rpush(final String key, final int liveTime, final String... values) {         return redisTemplate.execute(new RedisCallback<Long>() {             public Long doInRedis(RedisConnection connection)                     throws DataAccessException {                 long result = 0;                 for (String v : values) {                     connection.rPush(key.getBytes(), v.getBytes());                 }                 if (liveTime > 0) {                     connection.expire(key.getBytes(), liveTime);                 }                   return result;             }         });     }     /**      * 从队列的右边取出一条数据      *      * @param key      *            列表名      * @return      */     public String rpop(final String key) {         return redisTemplate.execute(new RedisCallback<String>() {             public String doInRedis(RedisConnection connection)                     throws DataAccessException {                 byte[] result = connection.rPop(key.getBytes());                 if(result != null ){                     try {                         return new String (result, redisCode);                     } catch (UnsupportedEncodingException e) {                         e.printStackTrace();                     }                 }                 return "";             }         });     }     /**      * 把一个值添加到对应列表中      *      * @param key      *            列表名      * @param index      *            　添加的位置      * @param value      *            　数据      * @return      */     public String lset(final String key, final long index, final String value) {         return redisTemplate.execute(new RedisCallback<String>() {             public String doInRedis(RedisConnection connection)                     throws DataAccessException {                 connection.lSet(key.getBytes(), index, value.getBytes());                 return "success";             }         });     }     /**      * 把所有数据添加到一个列表中      *      * @param key      *            列表名      * @param values      *            　数据      * @return      */     public long lpush(String key, String... values) {         return this.lpush(key, 0, values);     }     /**      * 把所有数据添加到一个列表中,并且设置列表的存活时间      *      * @param key      *            列表名      * @param values      *            数据      * @param liveTime      *            存活时间--单位(秒)      * @return      */     public long lpush(final String key,final  int liveTime, final String... values) {         return redisTemplate.execute(new RedisCallback<Long>() {             public Long doInRedis(RedisConnection connection)                     throws DataAccessException {                 long result = 0;                 for (String v : values){                     result = connection.lPush(key.getBytes(), v.getBytes());                 }                 if (liveTime > 0) {                     connection.expire(key.getBytes(), liveTime);                 }                 return result;             }         });     }     /**      * 返回列表的长度      *      * @param key      * @return      */     public long llen(final String key) {         return redisTemplate.execute(new RedisCallback<Long>() {             public Long doInRedis(RedisConnection connection)                     throws DataAccessException {                 return connection.lLen(key.getBytes());             }         });     }     /**      * 删除列表中对应值的元素      *      * @param key      *            列表名      * @param count      *            删除多少个相同的元素      * @param value      *            数据      * @return      */     public long lrem(final String key, final long count, final String value) {         return redisTemplate.execute(new RedisCallback<Long>() {             public Long doInRedis(RedisConnection connection)                     throws DataAccessException {                 return connection.lRem(key.getBytes(), count, value.getBytes());             }         });     }     /**      * 通过keys批量删除      *      * @param key      */     public long del(final String... keys) {         return redisTemplate.execute(new RedisCallback<Long>() {             public Long doInRedis(RedisConnection connection)                     throws DataAccessException {                 long result = 0;                 for (String k : keys) {                     result = connection.del(k.getBytes());                 }                 return result;             }         });     }           /**      *      * //DESC 删除单个key      * @time: 2016年5月27日 上午9:00:36      * @param key      * @return      * @throws      */     public long del(final String key){         return redisTemplate.execute(new RedisCallback<Long>(){             @Override             public Long doInRedis(RedisConnection connection)                     throws DataAccessException {                 return connection.del(key.getBytes());             }                       });     }                 /**      * 添加key value 并且设置存活时间(byte)      *      * @param key      * @param value      * @param liveTime      */     public void set(final byte[] key, final byte[] value, final long liveTime) {         redisTemplate.execute(new RedisCallback<Long>() {             public Long doInRedis(RedisConnection connection)                     throws DataAccessException {                 connection.set(key, value);                 if (liveTime > 0) {                     connection.expire(key, liveTime);                 }                 return 1L;             }         });               }     /**      * 添加key value 并且设置存活时间      *      * @param key      * @param value      * @param liveTime      *            单位秒      */     public void set(String key, String value, long liveTime) {         this.set(key.getBytes(), value.getBytes(), liveTime);               }     /**      * 添加key value      *      * @param key      * @param value      */     public void set(String key, String value) {         this.set(key, value, 0L);     }           /**      * 添加key value      *      * @param key      * @param value      */     public void setMulti(final Map<String,String> map) {         setMulti(map,0L);     }           /**      * 添加key value      *      * @param key      * @param value      */     public void setMulti(final Map<String,String> map,final long liveTime) {          redisTemplate.executePipelined(new RedisCallback<String>() {             public String doInRedis(RedisConnection connection)                     throws DataAccessException {                 Set<Map.Entry<String, String >> set = map.entrySet();                 for (Entry<String, String> entry : set) {                     connection.set(entry.getKey().getBytes(), entry.getValue().getBytes());                     if (liveTime > 0) {                         connection.expire(entry.getKey().getBytes(), liveTime);                     }                 }                 return null;             }         });     }     /**      * 添加key value (字节)(序列化)      *      * @param key      * @param value      */     public void set(byte[] key, byte[] value) {         this.set(key, value, 0L);               }     /**      * 获取redis value (String)      *      * @param key      * @return      */     public String get(final String key) {         return redisTemplate.execute(new RedisCallback<String>() {             public String doInRedis(RedisConnection connection)                     throws DataAccessException {             byte[] result = connection.get(key.getBytes());             if (result != null) {                 try {                     return new String (result ,redisCode);                 } catch (UnsupportedEncodingException e) {                     e.printStackTrace();                 }               }             return "";             }         });     }     /**      * 如果key不存在添加key value 并且设置存活时间(byte)，当key已经存在时，就不做任何操作      *      * @param key      * @param value      * @param liveTime      */     public long setnx(final byte[] key, final byte[] value, final long liveTime) {         return redisTemplate.execute(new RedisCallback<Long>() {             public Long doInRedis(RedisConnection connection)                     throws DataAccessException {                 long result = 0l;                 boolean isSuccess = connection.setNX(key, value);                 if (isSuccess) {                     if (liveTime > 0) {                         connection.expire(key, liveTime);                     }                     result = 1l;                 }                 return result;             }         });     }     /**      * 如果key不存在添加key value 并且设置存活时间，当key已经存在时，就不做任何操作      *      * @param key      * @param value      * @param liveTime      *            单位秒      */     public long setnx(String key, String value, long liveTime) {         return this.setnx(key.getBytes(), value.getBytes(), liveTime);               }     /**      * 如果key不存在添加key value，当key已经存在时，就不做任何操作      *      * @param key      * @param value      */     public long setnx(String key, String value) {         return this.setnx(key, value, 0L);     }     /**      * 如果key不存在添加key value (字节)(序列化)，当key已经存在时，就不做任何操作      *      * @param key      * @param value      */     public long setnx(byte[] key, byte[] value) {         return this.setnx(key, value, 0L);               }     /**      * 通过正则匹配keys      *      * @param pattern      * @return      */     public Set<String> keys(final String pattern) {         return redisTemplate.execute(new RedisCallback<Set<String>>() {             public Set<String> doInRedis(RedisConnection connection)                     throws DataAccessException {             Set<String> result = new HashSet<String>();             Set<byte[]>   data = connection.keys(pattern.getBytes());             for(byte[] d : data){                 try {                     result.add(new String(d,redisCode));                 } catch (UnsupportedEncodingException e) {                     e.printStackTrace();                 }             }             return result;             }         });     }     /**      * 检查key是否已经存在      *      * @param key      * @return      */     public boolean exists(final String key) {         return redisTemplate.execute(new RedisCallback<Boolean>() {             public Boolean doInRedis(RedisConnection connection)                     throws DataAccessException {                 return connection.exists(key.getBytes());             }                       });     }     /**      * 清空redis 所有数据      *      * @return      */     public String flushDB() {         return redisTemplate.execute(new RedisCallback<String>() {             public String doInRedis(RedisConnection connection)                     throws DataAccessException {                 connection.flushDb();                 return "success";             }         });     }     /**      * 查看redis里有多少数据      */     public long dbSize() {         return redisTemplate.execute(new RedisCallback<Long>() {             public Long doInRedis(RedisConnection connection)                     throws DataAccessException {                 return connection.dbSize();             }         });     }     /**      * 检查是否连接成功      *      * @return      */     public String ping() {         return redisTemplate.execute(new RedisCallback<String>() {             public String doInRedis(RedisConnection connection)                     throws DataAccessException {                 return connection.ping();             }         });     }     /**      * 设置key的生命周期      *      * @param key      * @param seconds      *            单位(秒)      * @return      */     public boolean expire(final String key, final long seconds) {         return redisTemplate.execute(new RedisCallback<Boolean>() {             public Boolean doInRedis(RedisConnection connection)                     throws DataAccessException {                 return connection.expire(key.getBytes(), seconds);             }         });     }     /**      * 自增长      *      * @param key      * @param length 增长步长      * @return      */     public long incr (final String key){         return redisTemplate.execute(new RedisCallback<Long>() {             public Long doInRedis(RedisConnection connection)                     throws DataAccessException {                 return connection.incr(key.getBytes());             }                       });     }     /**      * 自增长      *      * @param key      * @param length 增长步长      * @return      */     public long incrBy (final String key, final long len){         return redisTemplate.execute(new RedisCallback<Long>() {             public Long doInRedis(RedisConnection connection)                     throws DataAccessException {                 return connection.incrBy(key.getBytes(), len);             }         });               }     /**      * 自增长      *      * @param key      * @param length 增长步长      * @return      */     public double incrBy (final String key, final double len){         return redisTemplate.execute(new RedisCallback<Double>() {             public Double doInRedis(RedisConnection connection)                     throws DataAccessException {                 return connection.incrBy(key.getBytes(), len);             }         });     }           public long eval(final String luaCommand) {         return redisTemplate.execute(new RedisCallback<Long>() {             public Long doInRedis(RedisConnection connection) throws DataAccessException {                 return connection.eval(luaCommand.getBytes(), null,0);             }         });     }   }

　　

缓存应用：

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package com.eshore.ismp.cache.processor;   import org.apache.log4j.Logger; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import org.springframework.util.StringUtils;   import com.alibaba.fastjson.JSON; import com.alibaba.fastjson.JSONObject; import com.eshore.ismp.cache.redis.RedisService; import com.eshore.ismp.common.entity.ResultInfo;   /**  *  * //DESC: 管理门户缓存接口  * @author zzx  * @date 2016年5月20日 上午11:50:25  */ @Service public class AdminWebProcessor {     private static final Logger logger = Logger.getLogger(AdminWebProcessor.class);     private static final String ADMINWEB_USER = "ADMINWEB_USER_";     private static final Long LIVETIME = 60*30L;     @Autowired     RedisService redisService;           public String put(JSONObject param){         Long userId = param.getLong("user_id");         String userInfo = param.getString("user_info");         ResultInfo  rs = new ResultInfo();         if(userId==null || StringUtils.isEmpty(userInfo)){             logger.error("参数错误");             rs.setResult_code(2501);             rs.setResult_detail("参数错误");             return JSON.toJSONString(rs);         }         String key = ADMINWEB_USER+userId;         redisService.set(key , userInfo,LIVETIME);         rs.setResult_code(0);         rs.setResult_detail("success");         return JSON.toJSONString(rs);     }           public String get(JSONObject param){         Long userId = param.getLong("user_id");         String key = ADMINWEB_USER+userId;         ResultInfo  rs = new ResultInfo();         String user = redisService.get(key);         rs.setResult_code(0);         rs.setResult_detail("success");         rs.setResult_data(user);         return JSON.toJSONString(rs);     }           public String delete(JSONObject param){         Long userId = param.getLong("user_id");         String key = ADMINWEB_USER+userId;         ResultInfo  rs = new ResultInfo();         long isDel = redisService.del(key);         rs.setResult_code(0);         rs.setResult_detail("success");         return JSON.toJSONString(rs);     }   }