java 数据缓存

z_gxjs

浏览: 7206 次
性别:
来自: 北京

最近访客更多访客>>

xingming_03

lys221221

爱无疆

xushuai_025_55

博主相关

博客

微博

相册

留言

关于我

文章分类

社区版块

存档分类

博客分类：

java 缓存 cache

cache map java 缓存

/**
* 第一步缓存对象
*/

package org.nms.cache;

/**
* @ClassName: DataCacheEntity
* @Description: TODO( DataCacheEntity 缓存对象)
* @author z_gxjs_zhangyc
* @date Jul 17, 2012 3:14:14 PM
* @version 1.0
*/
public class CacheEntity {
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 CacheEntity() {
             super();
     }

     public CacheEntity(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;
     }
}

/**
* 第二步管理缓存
*/

package org.nms.cache;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;

/**
* @ClassName: CacheManager
* @Description: TODO( CacheManager 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
* @author z_gxjs_zhangyc
* @date Jul 17, 2012 3:15:49 PM
* @version 1.0
*/
@SuppressWarnings("unchecked")
public class CacheManager {

public 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 CacheEntity getCache(String key) {
        return (CacheEntity) 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<CacheEntity> i = cacheMap.entrySet().iterator();
        String key;
        ArrayList<String> arr = new ArrayList<String>();
        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, CacheEntity obj) {
        cacheMap.put(key, obj);
    }

    //获取缓存信息
    public static CacheEntity getCacheInfo(String key) {

        if (hasCache(key)) {
        CacheEntity 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, CacheEntity obj, long dt,boolean expired) {
    CacheEntity cache = new CacheEntity();
        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,CacheEntity obj,long dt){
    CacheEntity cache = new CacheEntity();
        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(CacheEntity 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
    @SuppressWarnings("finally")
public static ArrayList<String> 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
    @SuppressWarnings("finally")
public static ArrayList<String> 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;
        }
    }
}

/**
* 第三步测试
*/

package org.nms.cache;

import java.util.Iterator;
import java.util.Map.Entry;

/**
* @ClassName: CacheTest
* @Description: TODO( CacheTest 测试类)
* @author z_gxjs_zhangyc
* @date Jul 18, 2012 10:27:32 AM
* @version 1.0
*/
public class CacheTest {

@SuppressWarnings("unchecked")
public static void main(String[] args) {

  System.out.println(CacheManager.getSimpleFlag("test"));

        CacheManager.putCache("abc", new CacheEntity());
        CacheManager.putCache("def", new CacheEntity());
        CacheManager.putCache("ccc", new CacheEntity());
        CacheManager.clearOnly("");

        CacheEntity c = new CacheEntity();
        for (int i = 0; i < 10; i++) {
        CacheManager.putCache("" + i, c);
        c.setValue("zhangyc 做的测试数据");
        c.setTimeOut(12);
        }

        CacheManager.putCache("zhangyc", c);
        CacheManager.putCache("test;alskd", c);
        CacheManager.putCache("testasdfasdfasd", c);
        CacheManager.putCache("abcoqiwhcy", c);
        System.out.println("删除前的大小："+CacheManager.getCacheSize());
        CacheManager.getCacheAllkey();
        CacheManager.clearAll("test");
        System.out.println("删除后的大小："+CacheManager.getCacheSize());
        CacheManager.getCacheAllkey();

        Iterator<CacheEntity> it = CacheManager.cacheMap.entrySet().iterator();
        try {
            while (it.hasNext()) {
                Entry entry = (Entry) it.next();
                String key = (String) entry.getKey();
                CacheEntity ce= CacheManager.getCacheInfo(key);
                System.out.println("对象"+key+"："+ce.getValue());
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
}
}

cache.rar (7.7 KB)
下载次数: 44

分享到：