日志是在哪里声明的？

Question

我正在尝试向deeplearning4j提出一个补丁，但首先我需要能够构建该项目。我可以使用手册从maven构建它，但是IntelliJ (2016.3.6)发现了错误，当我查看源代码时，我不会责怪它。

让我感到困惑的源文件是https://github.com/deeplearning4j/deeplearning4j/blob/master/deeplearning4j-nlp-parent/deeplearning4j-nlp/src/main/java/org/deeplearning4j/models/word2vec/StaticWord2Vec.java，它有两个对变量log的引用，这个变量没有在这个文件中声明。

package org.deeplearning4j.models.word2vec;

import lombok.extern.slf4j.Slf4j;
import org.deeplearning4j.models.embeddings.WeightLookupTable;
import org.deeplearning4j.models.embeddings.reader.ModelUtils;
import org.deeplearning4j.models.embeddings.wordvectors.WordVectors;
import org.deeplearning4j.models.word2vec.wordstore.VocabCache;
import org.nd4j.linalg.api.ndarray.INDArray;
import org.nd4j.linalg.compression.AbstractStorage;
import org.nd4j.linalg.factory.Nd4j;
import org.nd4j.linalg.ops.transforms.Transforms;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * This is special limited Word2Vec implementation, suited for serving as lookup table in concurrent multi-gpu environment
 * This implementation DOES NOT load all vectors onto any of gpus, instead of that it holds vectors in, optionally, compressed state in host memory.
 * This implementation DOES NOT provide some of original Word2Vec methods, such as wordsNearest or wordsNearestSum.
 *
 * @author raver119@gmail.com
 */
@Slf4j
public class StaticWord2Vec implements WordVectors {
    private List<Map<Integer, INDArray>> cacheWrtDevice = new ArrayList<>();
    private AbstractStorage<Integer> storage;
    private long cachePerDevice = 0L;
    private VocabCache<VocabWord> vocabCache;
    private String unk = null;
 ... snipped

该类扩展接口，但不显式扩展父类。使用javap检查Maven生成的类文件，我看到：

Compiled from "StaticWord2Vec.java"
public class org.deeplearning4j.models.word2vec.StaticWord2Vec 
implements org.deeplearning4j.models.embeddings.wordvectors.WordVectors {
private static final org.slf4j.Logger log;
... snipped

Answer 1

我终于注意到了注释@Slf4j并跟踪了import语句，发现我需要将Lombok plugin添加到IntelliJ中才能构建此项目。