- package cc.util.cache;
- import java.io.Serializable;
- import java.util.Objects;
- /**
- 封装网络数据, 将数据的Etag、lastModified获取到, 下次请求的时候提取出来到服务器比对
- * Help to wrap byte data which obtains from network, It will work with {@link cc.util.cache.NetChacheManager}
- * @author wangcccong
- * @version 1.1406
- * <br> create at: Tues, 10 Jun 2014
- */
- public class NetByteWrapper implements Serializable {
- private final static long serialVersionUID = 1L;
- /** data from network */
- private byte[] data;
- /** data size */
- int contentLength;
- /** latested modify time */
- private long lastModified;
- /** ETag: look up HTTP Protocol */
- private String ETag;
- public NetByteWrapper(byte[] data, long lastModified, String Etag) {
- this.data = data;
- this.lastModified = lastModified;
- this.ETag = Etag;
- }
- public byte[] getData() {
- return data;
- }
- public void setData(byte[] data) {
- this.data = data;
- }
- public long getLastModified() {
- return lastModified;
- }
- public void setLastModified(long lastModified) {
- this.lastModified = lastModified;
- }
- public String getETag() {
- return ETag;
- }
- public void setETag(String eTag) {
- this.ETag = eTag;
- }
- public int getContentLength() {
- return Objects.isNull(data) ? 0 : data.length;
- }
- }
- package cc.util.cache;
- import java.lang.ref.ReferenceQueue;
- import java.lang.ref.SoftReference;
- /**采用软引用方式将数据存放起来
- * enclose {@link cc.util.cache.NetByteWrapper} with {@link java.lang.ref.SoftReference}, In order to recycle the memory
- * @author wangcccong
- * @version 1.1406
- * <br> create at: Tues, 10 Jun. 2014
- */
- public class NetByteSoftReference extends SoftReference<NetByteWrapper> {
- private String key = "";
- private long length = 0;
- public NetByteSoftReference(String key, NetByteWrapper arg0) {
- this(key, arg0, null);
- }
- public NetByteSoftReference(String key, NetByteWrapper arg0,
- ReferenceQueue<? super NetByteWrapper> arg1) {
- super(arg0, arg1);
- // TODO Auto-generated constructor stub
- this.key = key;
- this.length = arg0.getContentLength();
- }
- public String getKey() {
- return key;
- }
- public long getLength() {
- return length;
- }
- }
- package cc.util.cache;
- import java.lang.ref.ReferenceQueue;
- import java.lang.ref.SoftReference;
- import java.io.FileInputStream;
- import java.io.FileOutputStream;
- import java.io.ObjectInputStream;
- import java.io.ObjectOutputStream;
- import java.util.Iterator;
- import java.util.LinkedHashMap;
- import java.util.Objects;
- /**
- * 采用LinkedHashMap自带的LRU 算法缓存数据, 可检测对象是否已被虚拟机回收,并且重新计算当前缓存大小,清除缓存中无用的键值对象(即已经被虚拟机回收但未从缓存清除的数据);
- * 默认内存缓存大小为: 4 * 1024 * 1024 可通过通过setMaxCacheSize重新设置缓存大小,可手动清空内存缓存,支持采用内存映射方式读取缓存
- * <br>支持内存缓存和磁盘缓存方式, 通过 {@link cc.util.cache.NetByteWrapper} 支持HTTP缓存 (注:详细参考cc.util.http包)
- * @author wangcccong
- * @version 1.1406
- * <br> create at: Tues, 10 Jun 2014
- */
- public class NetCacheManager {
- /** max cache size */
- private long MAX_CACHE_SIZE = 4 * 1024 * 1024;
- private long cacheSize = 0;
- private static NetCacheManager instance = null;
- private final ReferenceQueue<NetByteWrapper> referenceQueue;
- private final LinkedHashMap<String, NetByteSoftReference> cacheMap;
- private NetCacheManager(){
- referenceQueue = new ReferenceQueue<NetByteWrapper>();
- cacheMap = new LinkedHashMap<String, NetByteSoftReference>(16, 0.75f, true) {
- private static final long serialVersionUID = -8378285623387632829L;
- @Override
- protected boolean removeEldestEntry(
- java.util.Map.Entry<String, NetByteSoftReference> eldest) {
- // TODO Auto-generated method stub
- boolean shouldRemove = cacheSize > MAX_CACHE_SIZE;
- if (shouldRemove) {
- cacheSize -= eldest.getValue().getLength();
- System.gc();
- }
- return shouldRemove;
- }
- };
- }
- /** singleton model */
- public static synchronized NetCacheManager newInstance(){
- if (Objects.isNull(instance)) {
- instance = new NetCacheManager();
- }
- return instance;
- }
- /**
- * reset the memory cache size
- * @param cacheSize
- */
- public void setMaxCacheSize(long cacheSize) {
- this.MAX_CACHE_SIZE = cacheSize;
- }
- /**
- * 获取当前内存缓存大小
- * @return
- */
- public long getCacheSize() {
- return cacheSize;
- }
- /**
- * 将数据缓存至内存, 如果http返回的数据<b>不支持</b>缓存则采用此方法,缓存的key一般为请求的url
- * @param key
- * @param value
- */
- public void cacheInMemory(String key, byte[] value) {
- this.cacheInMemory(key, value, 0, null);
- }
- /**
- * 将数据缓存至内存, 如果http返回的数据<b>支持</b>缓存则采用此方法
- * @param key
- * @param value
- * @param lastModified
- */
- public void cacheInMemory(String key, byte[] value, long lastModified) {
- this.cacheInMemory(key, value, lastModified, null);
- }
- /**
- * 将数据缓存至内存, 如果http返回的数据<b>支持</b>缓存则采用此方法
- * @param key
- * @param value
- * @param Etags
- */
- public void cacheInMemory(String key, byte[] value, String Etags) {
- this.cacheInMemory(key, value, 0, Etags);
- }
- /**
- * 将数据缓存至内存, 如果http返回的数据<b>支持</b>缓存则采用此方法
- * @param key
- * @param value
- * @param lastModified
- * @param Etags
- */
- private void cacheInMemory(String key, byte[] value, long lastModified, String Etags) {
- Objects.requireNonNull(key, "key must not be null");
- clearRecycledObject();
- NetByteWrapper wrapper = new NetByteWrapper(value, lastModified, Etags);
- NetByteSoftReference byteRef = new NetByteSoftReference(key, wrapper, referenceQueue);
- cacheMap.put(key, byteRef);
- value = null;
- wrapper = null;
- }
- /**
- * 缓存至磁盘, 默认不首先缓存到内存
- * @param key
- * @param value
- * @param path
- */
- public void cacheInDisk(String key, byte[] value, String path) {
- cacheInDisk(key, value, path, false);
- }
- /**
- *
- * @param key
- * @param value
- * @param path
- * @param cacheInMemory
- */
- public void cacheInDisk(String key, byte[] value, String path, boolean cacheInMemory) {
- this.cacheInDisk(key, value, 0, null, path, cacheInMemory);
- }
- /**
- *
- * @param key
- * @param value
- * @param lastModified
- * @param Etags
- * @param path
- * @param cacheInMemory
- */
- private void cacheInDisk(String key, byte[] value, long lastModified, String Etags, String path, boolean cacheInMemory) {
- if (cacheInMemory) cacheInMemory(key, value, lastModified, Etags);
- try (FileOutputStream fos = new FileOutputStream(path);
- ObjectOutputStream oos = new ObjectOutputStream(fos)) {
- NetByteWrapper wrapper = new NetByteWrapper(value, lastModified, Etags);
- oos.writeObject(wrapper);
- } catch (Exception e) {
- // TODO: handle exception
- e.printStackTrace();
- }
- }
- /**
- * get {@link cc.util.cache.NetByteWrapper} from memory according to key
- * @param key
- * @return {@link cc.util.cache.NetByteWrapper}
- */
- public NetByteWrapper getFromMemory(String key) {
- SoftReference<NetByteWrapper> softReference = cacheMap.get(key);
- return Objects.nonNull(softReference) ? softReference.get() : null;
- }
- /**
- * get byte[] from memory according to key
- * @param context
- * @param key
- * @return
- */
- public byte[] getByteFromMemory(String key) {
- NetByteWrapper wrapper = getFromMemory(key);
- return Objects.nonNull(wrapper) ? wrapper.getData() : null;
- }
- /**
- * 从磁盘获取数据
- * @param path
- * @return {@link cc.util.cache.NetByteWrapper}
- */
- public NetByteWrapper getFromDisk(String path) {
- try (FileInputStream fis = new FileInputStream(path);
- ObjectInputStream ois = new ObjectInputStream(fis)) {
- NetByteWrapper wrapper = (NetByteWrapper) ois.readObject();
- return wrapper;
- } catch (Exception e) {
- // TODO: handle exception
- e.printStackTrace();
- return null;
- }
- }
- /**
- * 采用内存映射的方式从磁盘获取数据(加快读取缓存的大文件)
- * @param path
- * @return
- */
- public NetByteWrapper getFromDiskByMapped(String path) {
- try (FileInputStream fis = new FileInputStream(path);
- FileChannel channel= fis.getChannel();
- ByteArrayOutputStream baos = new ByteArrayOutputStream()){
- MappedByteBuffer mbb = channel.map(FileChannel.MapMode.READ_ONLY, 0, channel.size());
- byte[] bts = new byte[1024];
- int len = (int) channel.size();
- for (int offset = 0; offset < len; offset += 1024) {
- if (len - offset > 1024) mbb.get(bts);
- else mbb.get((bts = new byte[len - offset]));
- baos.write(bts);
- }
- ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
- ObjectInputStream ois = new ObjectInputStream(bais);
- NetByteWrapper wrapper = (NetByteWrapper) ois.readObject();
- bais.close();
- ois.close();
- return wrapper;
- } catch (Exception e) {
- // TODO: handle exception
- e.printStackTrace();
- return null;
- }
- }
- /**
- * 从磁盘获取缓存的byte[] 数据
- * @param path
- * @return
- */
- public byte[] getByteFromDisk(String path) {
- NetByteWrapper wrapper = getFromDisk(path);
- return Objects.isNull(wrapper) ? null : wrapper.getData();
- }
- /**
- * 通过内存映射放射从磁盘获取缓存的byte[] 数据
- * @param path
- * @return
- */
- public byte[] getByteFromDiskByMapped(String path) {
- NetByteWrapper wrapper = getFromDiskByMapped(path);
- return Objects.isNull(wrapper) ? null : wrapper.getData();
- }
- /**
- * calculate the size of the cache memory
- */
- private void clearRecycledObject() {
- NetByteSoftReference ref = null;
- //检测对象是否被回收,如果被回收则从缓存中移除死项
- while (Objects.nonNull((ref = (NetByteSoftReference) referenceQueue.poll()))) {
- cacheMap.remove(ref.getKey());
- }
- cacheSize = 0;
- Iterator<String> keys = cacheMap.keySet().iterator();
- while (keys.hasNext()) {
- cacheSize += cacheMap.get(keys.next()).getLength();
- }
- }
- /**
- * clear the memory cache
- */
- public void clearCache() {
- clearRecycledObject();
- cacheMap.clear();
- System.gc();
- System.runFinalization();
- }
- }
- //该片段来自于http://www.codesnippet.cn/detail/1108201513410.html
来源: http://www.codesnippet.cn/detail/1108201513410.html