我会用番石榴的Suppliers.memoizeWithExpiration（供应商委托，持续时间长，TimeUnit单位）
public class JdkVersionService {
@Inject
private JdkVersionWebService jdkVersionWebService;
// No need to check too often. Once a year will be good :)
private final supplier<JdkVersion> latestJdkVersionCache
= suppliers.memoizeWithExpiration(jdkVersionsupplier(), 365, TimeUnit.DAYS);
public JdkVersion getLatestJdkVersion() {
return latestJdkVersionCache.get();
}
private supplier<JdkVersion> jdkVersionsupplier() {
return new supplier<JdkVersion>() {
public JdkVersion get() {
return jdkVersionWebService.checkLatestJdkVersion();
}
};
}
}
今天，我将使用JDK 8方法参考和构造函数注入来编写更清晰的代码，以不同的方式编写此代码：
import java.util.concurrent.TimeUnit;
import java.util.function.supplier;
import javax.inject.Inject;
import org.springframework.stereotype.Service;
import com.google.common.base.suppliers;
@Service
public class JdkVersionService {
private final supplier<JdkVersion> latestJdkVersionCache;
@Inject
public JdkVersionService(JdkVersionWebService jdkVersionWebService) {
this.latestJdkVersionCache = suppliers.memoizeWithExpiration(
jdkVersionWebService::checkLatestJdkVersion,
365, TimeUnit.DAYS
);
}
public JdkVersion getLatestJdkVersion() {
return latestJdkVersionCache.get();
}
}
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