我从书中复制的示例开始学习使用 mahout。但是，eclipse 编译器给了我以下信息：
> Exception in thread "main" java.lang.NoClassDefFoundError: org/slf4j/LoggerFactory
at org.apache.mahout.cf.taste.impl.model.file.FileDataModel.<clinit>(FileDataModel.java:119)
at mia.recommender.ch02.RecommenderIntro.main(RecommenderIntro.java:18)
Caused by: java.lang.ClassNotFoundException: org.slf4j.LoggerFactory
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
... 2 more
在我看来，问题来自属于这个库本身的 FileDataModel.java。如何追溯或分析此错误。
示例代码如下，正是从书中复制的。造成问题的线路是
DataModel model = new FileDataModel(new File("intro.csv"));
import org.apache.mahout.cf.taste.impl.model.file.*;
import org.apache.mahout.cf.taste.impl.neighborhood.*;
import org.apache.mahout.cf.taste.impl.recommender.*;
import org.apache.mahout.cf.taste.impl.similarity.*;
import org.apache.mahout.cf.taste.model.*;
import org.apache.mahout.cf.taste.neighborhood.*;
import org.apache.mahout.cf.taste.recommender.*;
import org.apache.mahout.cf.taste.similarity.*;
import java.io.*;
import java.util.*;
class RecommenderIntro {
public static void main(String[] args) throws Exception {
DataModel model = new FileDataModel(new File("intro.csv"));
UserSimilarity similarity = new PearsonCorrelationSimilarity(model);
UserNeighborhood neighborhood =
new NearestNUserNeighborhood(2, similarity, model);
Recommender recommender = new GenericUserBasedRecommender(
model, neighborhood, similarity);
List<RecommendedItem> recommendations =
recommender.recommend(1, 1);
for (RecommendedItem recommendation : recommendations) {
System.out.println(recommendation);
}
}
}