Question

我正在尝试一个简短的电影推荐人，在这里引用一个简短的视频 - https://www.youtube.com/watch?v=63k560Livmg。我正在尝试diff而不是控制台，我想在浏览器上显示建议，所以我使用servlet。但问题是当我在表单中输入值（用户ID）时，会显示空白屏幕。请帮助我做错了。来自此处的数据集 - https://mahout.apache.org/users/recommender/userbased-5-minutes.html。请参阅附加的web.xml和层次结构截图。

的index.jsp

    <html>
    <body>
     <h2>Hello World!</h2>
     <form action="demo" method="post">  
     loginID:<input type="text" name="name"/><br/>
     <input type="submit" value="login"/> 

    </form>
    </body>
    </html>

demo.java- servlet，用于收集用户值和显示结果。

  package com.issac;

  import java.io.IOException;
  import java.io.PrintWriter;
  import java.util.ArrayList;
   import java.util.List;

  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.recommender.RecommendedItem;

/**
* Servlet implementation class demo
 */
   public class demo extends HttpServlet {
   private static final long serialVersionUID = 1L;

/**
 * @see HttpServlet#HttpServlet()
 */
      public demo() {
      super();
    // TODO Auto-generated constructor stub
    }

/**
 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
 */
     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
      response.getWriter().append("Served at:   ").append(request.getContextPath());
   }

/**
 * @throws IOException 
 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
 */
     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
    // TODO Auto-generated method stub

        String n = request.getParameter("name");
        int k = Integer.parseInt(n);
        PrintWriter out = response.getWriter();
        List<RecommendedItem> recommendations = new ArrayList<RecommendedItem>  ();

       try {
          recommendations = App.getRecommend(k);
        } catch (Exception e) {
        // TODO Auto-generated catch block
            e.printStackTrace();
        }

          for (RecommendedItem recommendation : recommendations) {
          out.println(recommendation);





  }

 }}

app.java - 用于生成推荐的逻辑

      package com.issac;

      import java.io.File;
      import java.util.List;

      import org.apache.mahout.cf.taste.impl.model.file.FileDataModel;
      import org.apache.mahout.cf.taste.impl.neighborhood.ThresholdUserNeighborhood;
      import org.apache.mahout.cf.taste.impl.recommender.GenericUserBasedRecommender;
      import org.apache.mahout.cf.taste.impl.similarity.PearsonCorrelationSimilarity;
      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.UserBasedRecommender;
      import org.apache.mahout.cf.taste.similarity.UserSimilarity;


      public class App 
 {
    public static List<RecommendedItem> getRecommend(int k) throws Exception
 {
    DataModel model = new FileDataModel(new File("data/dataset.csv"));
    UserSimilarity similarity = new PearsonCorrelationSimilarity(model);
    UserNeighborhood neighborhood = new ThresholdUserNeighborhood(0.1,  similarity, model);
 UserBasedRecommender recommender = new      GenericUserBasedRecommender(model, neighborhood, similarity);
      List<RecommendedItem> recommendations = recommender.recommend(k, 3);
      return recommendations;
     }
  }

eclipse控制台的堆栈跟踪 -

         INFO: Server startup in 15288 ms
          SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
          SLF4J: Defaulting to no-operation (NOP) logger implementation
      SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
      java.io.FileNotFoundException: data\dataset.csv
      at org.apache.mahout.cf.taste.impl.model.file.FileDataModel.<init>   (FileDataModel.java:182)
      at org.apache.mahout.cf.taste.impl.model.file.FileDataModel.<init>(FileDataModel.java:169)
      at org.apache.mahout.cf.taste.impl.model.file.FileDataModel.<init>(FileDataModel.java:149)
      at com.issac.App.getRecommend(App.java:24)
      at com.issac.demo.doPost(demo.java:51)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
      at   org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilt erChain.java:292)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
   at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
  at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
  at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
  at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
  at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:528)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1100)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:687)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1520)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1476)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)

Answer 1

在JEE应用程序中，应通过getResourceAsStream方法读取文件：

try(InputStream input=getClass().getClassLoader().getResourceAsStream("data/dataset.csv")){
    ...
}

data文件夹应立即放在src/main/resources内。

在你的情况下，还存在一个并发症：由于缺少来自InputStream的DataModel的构造函数，我们需要首先将inputStream的内容保存到（临时）文件中：

try(InputStream input=getClass().getClassLoader().getResourceAsStream("data/dataset.csv")){
    // Copy the contents of the inputStream to a File, to fix the constructor FileDataModel(file):
    File tmp=File.createTempFile("model-", "");
    tmp.deleteOnExit();
    InputStream input=new ByteArrayInputStream("enero".getBytes("ISO-8859-1"));
    Files.copy(input, tmp.toPath(), StandardCopyOption.REPLACE_EXISTING);
    DataModel model = new FileDataModel(new File("data/dataset.csv"));
    ...
}

Answer 2

所以这就是我的成功之道。获取FileNotFound异常后，我尝试了这个 - ＆gt;

 ClassLoader classLoader = App.class.getClassLoader();
 DataModel model = new FileDataModel(new File(classLoader.getResource("data/dataset.csv").getFile()));

而不是

 DataModel model = new FileDataModel(new File("data/dataset.csv"));

我没有完全了解它为什么在互联网上找到它的工作，与类FileDataModel的参数有关。欢迎任何能够解释的人。

日食中的maven为data.csv文件提供filenotfound异常

2 个答案: