差異處
這裏顯示兩個版本的差異處。
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java:guava:cache:helloworld [2016/04/13 23:30] tony |
java:guava:cache:helloworld [2023/06/25 09:48] |
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| - | {{tag>java guava}} | ||
| - | ====== Guava Cache Hello World ====== | ||
| - | ===== Introduction ===== | ||
| - | 大部分應用程式都會透過Cache機制，去增加效能或暫時性的備援。Guava提供了簡單的Cache實做，讓你不用替資源回收或同步問題煩惱。 | ||
| - | ===== How to? ===== | ||
| - | 我們可以透過CacheBuilder去設定Cache的條件。在build時，你可以選擇要預先提供服務實做，或是在get時提供: | ||
| - | <code java> | ||
| - | package org.tonylin.practice.guava.cache; | ||
| - | import java.util.concurrent.TimeUnit; | ||
| - | |||
| - | import org.junit.Assert; | ||
| - | import org.junit.Test; | ||
| - | |||
| - | import com.google.common.cache.CacheBuilder; | ||
| - | import com.google.common.cache.CacheLoader; | ||
| - | import com.google.common.cache.LoadingCache; | ||
| - | |||
| - | public class TestCache { | ||
| - | @Test | ||
| - | public void testCache() throws Exception { | ||
| - | Cache<String, String> cache = CacheBuilder.newBuilder() | ||
| - | .maximumSize(10) | ||
| - | .expireAfterAccess(5, TimeUnit.SECONDS) | ||
| - | .expireAfterWrite(5, TimeUnit.SECONDS) | ||
| - | .softValues() | ||
| - | .build(); | ||
| - | |||
| - | Assert.assertEquals("0", cache.get("test1", ()->{return "0";})); | ||
| - | Thread.sleep(4000); | ||
| - | Assert.assertEquals("0", cache.get("test1", ()->{return "1";})); | ||
| - | Thread.sleep(2000); | ||
| - | Assert.assertNull(cache.getIfPresent("test1")); | ||
| - | Assert.assertEquals("2", cache.get("test1", ()->{return "2";})); | ||
| - | } | ||
| - | @Test | ||
| - | public void test() throws Exception { | ||
| - | LoadingCache<String, String> cache = CacheBuilder.newBuilder() | ||
| - | .maximumSize(10) | ||
| - | .expireAfterAccess(5, TimeUnit.SECONDS) | ||
| - | .expireAfterWrite(5, TimeUnit.SECONDS) | ||
| - | .softValues() | ||
| - | .build(new CacheLoader<String, String>(){ | ||
| - | private int count = 0; | ||
| - | @Override | ||
| - | public String load(String key) throws Exception { | ||
| - | return key + (count++); | ||
| - | } | ||
| - | }); | ||
| - | |||
| - | Assert.assertEquals("test10", cache.get("test1")); | ||
| - | Thread.sleep(4000); | ||
| - | Assert.assertEquals("test10", cache.get("test1")); | ||
| - | Thread.sleep(2000); | ||
| - | Assert.assertNull(cache.getIfPresent("test1")); | ||
| - | Assert.assertEquals("test11", cache.get("test1")); | ||
| - | } | ||
| - | } | ||
| - | </code> | ||
| - | ===== ===== | ||
| - | ---- | ||
| - | \\ | ||
| - | ~~DISQUS~~ | ||
