我运行了以下脚本(java),它给了我奇怪的结果。
有谁可以帮忙解释一下吗?
import java.util.Objects;
import org.apache.log4j.Logger;
public class CacheTester {
private static final Logger log = Logger.getLogger(CacheTester.class);
@Test
public void hashCodeTest() {
for (int i = 0; i < 50; i++) {
// if I remove the third parameter, it works fine
log.info(Objects.hash("getDemoCache", "1", new int[]{1, 2}));
}
}
}
日志结果(它们彼此不同):
//...
2015-04-29 17:43:20 INFO CacheTester:42 - 1431904540
2015-04-29 17:43:20 INFO CacheTester:42 - 1859187447
2015-04-29 17:43:20 INFO CacheTester:42 - -2146933580
2015-04-29 17:43:20 INFO CacheTester:42 - -2074242201
2015-04-29 17:43:20 INFO CacheTester:42 - 1363170000
2015-04-29 17:43:20 INFO CacheTester:42 - 1040980265
2015-04-29 17:43:20 INFO CacheTester:42 - 1639331053
2015-04-29 17:43:20 INFO CacheTester:42 - 570765746
2015-04-29 17:43:20 INFO CacheTester:42 - -2023288896
2015-04-29 17:43:20 INFO CacheTester:42 - -1892732019
2015-04-29 17:43:20 INFO CacheTester:42 - 1464306601
2015-04-29 17:43:20 INFO CacheTester:42 - 921799986
2015-04-29 17:43:20 INFO CacheTester:42 - 1037804977
//...
- - 背景 - -
我想使用我自己的 keyGenrator 来实现 @Cacheable 注释(Spring 和 ehCache)。
public Object generate(Object target, Method method, Object... params) {
int key = Objects.hashCode(method.getName(), params);
log.info("key = " + key);
return key;
}
在这种情况下,我发现缓存总是丢失。
那我必须改成这样:
public Object generate(Object target, Method method, Object... params) {
int result = method.getName().hashCode() : 0;
result = 31 * result + Objects.hashCode(params);
return result;
}
谢谢