gvsig-tools / org.gvsig.tools / library / trunk / org.gvsig.tools / org.gvsig.tools.lib / src / main / java / org / gvsig / tools / util / CachedValue.java @ 2335
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| 1 | 2096 | jjdelcerro | /**
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| 2 | * gvSIG. Desktop Geographic Information System.
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| 3 | *
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| 4 | 2100 | jjdelcerro | * Copyright (C) 2007-2020 gvSIG Association.
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| 5 | 2096 | jjdelcerro | *
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| 6 | * This program is free software; you can redistribute it and/or
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| 7 | * modify it under the terms of the GNU General Public License
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| 8 | * as published by the Free Software Foundation; either version 3
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| 9 | * of the License, or (at your option) any later version.
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| 10 | *
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| 11 | * This program is distributed in the hope that it will be useful,
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| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | * GNU General Public License for more details.
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| 15 | *
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| 16 | * You should have received a copy of the GNU General Public License
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| 17 | * along with this program; if not, write to the Free Software
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| 18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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| 19 | * MA 02110-1301, USA.
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| 20 | *
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| 21 | * For any additional information, do not hesitate to contact us
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| 22 | * at info AT gvsig.com, or visit our website www.gvsig.com.
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| 23 | */
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| 24 | package org.gvsig.tools.util; |
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| 25 | |||
| 26 | 2100 | jjdelcerro | import java.io.Closeable; |
| 27 | import java.io.IOException; |
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| 28 | import org.gvsig.tools.dispose.Disposable; |
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| 29 | import org.gvsig.tools.dispose.DisposeUtils; |
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| 30 | |||
| 31 | 2096 | jjdelcerro | /**
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| 32 | *
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| 33 | * @author jjdelcerro
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| 34 | */
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| 35 | public abstract class CachedValue<T> { |
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| 36 | |||
| 37 | 2100 | jjdelcerro | private T value = null; |
| 38 | private long lastAccess = 0; |
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| 39 | private long expireTimeInMillis; |
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| 40 | 2096 | jjdelcerro | |
| 41 | public CachedValue() {
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| 42 | this(3000); |
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| 43 | } |
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| 44 | |||
| 45 | public CachedValue(long expireTimeInMillis) { |
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| 46 | this.expireTimeInMillis = expireTimeInMillis;
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| 47 | } |
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| 48 | |||
| 49 | 2100 | jjdelcerro | protected void reload() { |
| 50 | // Overwrite this method.
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| 51 | } |
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| 52 | 2096 | jjdelcerro | |
| 53 | 2100 | jjdelcerro | protected final T getValue() { |
| 54 | return this.value; |
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| 55 | } |
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| 56 | |||
| 57 | protected void setValue(T value) { |
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| 58 | this.value = value;
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| 59 | } |
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| 60 | |||
| 61 | public final boolean isExpired() { |
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| 62 | 2096 | jjdelcerro | long now = System.currentTimeMillis(); |
| 63 | return (now - lastAccess) > expireTimeInMillis;
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| 64 | } |
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| 65 | |||
| 66 | 2100 | jjdelcerro | public final void set(T value) { |
| 67 | this.value = value;
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| 68 | lastAccess = System.currentTimeMillis();
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| 69 | } |
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| 70 | |||
| 71 | public final void setExpireTime(long expireTimeInMillis) { |
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| 72 | this.expireTimeInMillis = expireTimeInMillis;
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| 73 | } |
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| 74 | |||
| 75 | public final long getExpireTime() { |
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| 76 | return expireTimeInMillis;
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| 77 | } |
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| 78 | |||
| 79 | public final void resetAccess() { |
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| 80 | this.lastAccess = System.currentTimeMillis(); |
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| 81 | } |
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| 82 | |||
| 83 | public final void expired() { |
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| 84 | this.lastAccess = 0; |
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| 85 | } |
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| 86 | |||
| 87 | public final T get() { |
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| 88 | 2096 | jjdelcerro | if (isExpired()) {
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| 89 | 2100 | jjdelcerro | if( value instanceof Disposable ) { |
| 90 | DisposeUtils.disposeQuietly((Disposable) value); |
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| 91 | } else if( value instanceof Closeable ) { |
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| 92 | try {
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| 93 | ((Closeable)value).close();
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| 94 | } catch (IOException ex) { |
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| 95 | // Ignore
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| 96 | } |
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| 97 | } |
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| 98 | value = null;
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| 99 | 2096 | jjdelcerro | reload(); |
| 100 | } |
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| 101 | lastAccess = System.currentTimeMillis();
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| 102 | return value;
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| 103 | } |
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| 104 | } |