Question

EhCache似乎对用作内存缓存的密钥的对象没有限制，对磁盘/分布式缓存只有Serializable。（http://ehcache.org/apidocs/net/sf/ehcache/Element.html）

那么在内部使用密钥对象的哪个属性来检查密钥是否与存储密钥匹配？如果有什么方法可以用来提供我自己的身份方法？

Answer 1

因此，EHCache使用 equals / hashCode für密钥标识。

我做了一些测试：

private static final class TestKey implements Serializable {

    boolean equals;
    int hash;

    TestKey( boolean equals, int hash ){
        this.equals = equals;
        this.hash = hash;
    }

    @Override
    public boolean equals( Object other ){ return equals; }

    @Override
    public int hashCode(){ return hash; }
}




public void testIdentity() throws Exception {

    // A simple wrapper around EHCache which does the configuration
    // and provides a map like interface
    CacheEHCache<TestKey,String> cache = CacheEHCache.instance(
            new File( "/tmp/ehcache" ), "testcache", 10 );

    // May contain content from last run
    cache.clear();

    // equals and hash matches
    TestKey k11 = new TestKey( true, 1 );

    cache.put( k11, "Test11" );

    assertEquals( cache.size(), 1 );
    assertTrue( cache.containsKey( k11 ) );

    cache.remove( k11 );
    assertEquals( cache.size(), 0 );

    // doesn't equal but hash matches
    TestKey k21 = new TestKey( false, 1 );

    cache.put( k21, "Test21" );
    assertEquals( cache.size(), 1 );
    assertFalse( cache.containsKey( k21 ) );

    // This is interesting: Clear needs to find the objects to clear
    // So we must patch it.
    k21.equals = true; 
    cache.clear();
    assertEquals( cache.size(), 0 );

    // equals but hash missmatches
    TestKey k31 = new TestKey( true, 1 );
    TestKey k32 = new TestKey( true, 2 );
    cache.put( k31, "Test21" );
    assertEquals( cache.size(), 1 );
    assertTrue( cache.containsKey( k31 ) );
    assertFalse( cache.containsKey( k32 ) );
    cache.clear();
}

EhCache：什么用于密钥身份？

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