java - 如何分解 Java 8 和 SLF4J 中的条件日志检查？

Question

我正在尝试分解 if (log.isInfoEnabled()) 或 if (log.isWarnEnabled()) 语句，所以我想在中创建一个接口(interface)Java 8 如下所示，但我不确定我是否会遇到任何问题？

public interface Logging {

    Logger log_ = LoggerFactory.getLogger(Thread.currentThread().getContextClassLoader().getClass());

    default void logInfo(String... messages) {
        if (log_.isInfoEnabled()) {
            String meg = String.join("log message: ", messages)
            log_.info(msg);
        }
    }
}


public class Hello implements Logging {

    //Imagine this function is called lot of times like imagine
    // an infinite loop calling this function
    public void doSomething(String name) {
        if (name.equals("hello")) {
            logInfo("What class name does the log print here ? ")  
        }
    }

     //Imagine this function is called lot of times like imagine
    // an infinite loop calling this function
   public void doSomething2(String name) {
        if (name.equals("hello2")) {
            logInfo("What class name does the log print here ? ")  
        }
    }

    //Imagine this function is called lot of times like imagine
    // an infinite loop calling this function
    public void doSomething3(String name) {
        if (name.equals("hello3")) {
            logInfo("What class name does the log print here ? ")  
        }
    }
}

对比

public class Hello {

    Logger log_ = LoggerFactory.getLogger(Hello.class);

    public void doSomething(String name) {
        if (name.equals("hello")) {
            if (log_.isInfoEnabled()) { // Don't want to have this code everywhere
                logInfo("What class name does the log print here ? ") 
            }
        }
    }
}

这两个是等价的吗？使用上面的 Logging 接口(interface)有什么问题吗？

Answer 1

守卫(应该)主要用于在不需要时防止代价高昂的操作 - 仅用于调试。

所以下面是正确的模式:

    if (log_.isInfoEnabled()) {
        String meg = String.join("log message: ", f(), g(), h);
        log_.info(msg);
    }

default void logInfo(Supplier<String> messageSupplier) {
    if (log_.isInfoEnabled()) {
        log_.info(messageSupplier.get());
    }
}

logInfo(() -> String.join("log message: ", f(), g(), h));

但是，您冒着将此方法用于简单日志记录情况的风险，将其转换为代价高昂的额外函数调用 logInfo 和 lambda。