Archetype Created Web Applicationweb-recommenderWeb RecommenderWeb recommender servletRecommenderServlet1web-recommenderrecommendWeb/RecommenderServlet
③RecommenderServlet.java
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.mahout.cf.taste.impl.model.file.FileDataModel;
import org.apache.mahout.cf.taste.impl.neighborhood.NearestNUserNeighborhood;
import org.apache.mahout.cf.taste.impl.recommender.GenericUserBasedRecommender;
import org.apache.mahout.cf.taste.impl.similarity.EuclideanDistanceSimilarity;
import org.apache.mahout.cf.taste.model.DataModel;
import org.apache.mahout.cf.taste.neighborhood.UserNeighborhood;
import org.apache.mahout.cf.taste.recommender.RecommendedItem;
import org.apache.mahout.cf.taste.recommender.Recommender;
import org.apache.mahout.cf.taste.similarity.UserSimilarity;
public class RecommenderServlet extends HttpServlet {
private static final int NUM_TOP_PREFERENCES = 3;
private static final int DEFAULT_HOW_MANY = 3;
private Recommender recommender;
public void init(ServletConfig config) throws ServletException {
super.init(config);
try {
String csvPath= getServletContext().getRealPath("WEB-INF");
csvPath += File.separator + "critics.csv";
// モデル構築用のデータをファイルから読み込む
DataModel model = new FileDataModel(new File(csvPath));
// ユーザ類似性と類似ユーザ抽出のメソッドを決定
UserSimilarity similarity = new EuclideanDistanceSimilarity(model);
UserNeighborhood neighborhood = new NearestNUserNeighborhood(2,
similarity, model);
// ユーザベースの推薦を作成
recommender = new GenericUserBasedRecommender(model,
neighborhood, similarity);
}
catch (Exception e) {
throw new ServletException(e);
}
}
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException {
String userIDString = req.getParameter("userID");
if (userIDString == null) {
throw new ServletException("userID was not specified");
}
long userID = Long.parseLong(userIDString);
String howManyString = req.getParameter("howMany");
int howMany = howManyString == null ? DEFAULT_HOW_MANY : Integer.parseInt(howManyString);
try {
List items = recommender.recommend(userID, howMany);
writePlainText(resp, userID, items);
} catch (Exception te) {
throw new ServletException(te);
}
}
private void writePlainText(HttpServletResponse response, long userID,
Iterable items) throws IOException, Exception {
response.setContentType("text/plain");
response.setCharacterEncoding("UTF-8");
response.setHeader("Cache-Control", "no-cache");
PrintWriter writer = response.getWriter();
for (RecommendedItem recommendedItem : items) {
writer.print(recommendedItem.getValue());
writer.print('\t');
writer.println(recommendedItem.getItemID());
}
}
}
