tomcat - Servlet 3.0 HTTP 404-请求的资源()不可用

This question already has answers here:

Servlet returns “HTTP Status 404 The requested resource (/servlet) is not available”
                                
                                    （10个答案）
                                
                        
                                3年前关闭。
            
                    
环境：


Ubuntu 12.04
Apache Tomcat 7.0.27
Eclipse 4.2（Juno）
Servlet 3.0
Openjdk 7


尝试使用Servlet 3.0做FileCounter时，我在URL上收到此错误

http：// localhost：8080 / wtp.filecounter /。

不必是http：// localhost：8080 / wtp.filecounter / FileCounter吗？


  Estado HTTP 404-
  
  通知类型
  
  门萨耶
  
  descripciónEl recurso requerido（）没有错误。
  
  Apache Tomcat / 7.0.26


结构体

wtp.filecounter
   dao
      FileDao.java
   servlets
      FileCounter.java

FileDao.java读取并更新文件访问者

package wtp.filecounter.dao;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;

public class FileDao {

  public int getCount() {
    int count = 0;
    // Load the file with the counter
    FileReader fileReader = null;
    BufferedReader bufferedReader = null;
    PrintWriter writer = null ;
    try {
      File f = new File("FileCounter.initial");
      if (!f.exists()) {
        f.createNewFile();
        writer = new PrintWriter(new FileWriter(f));
        writer.println(0);
      }
      if (writer !=null){
        writer.close();
      }

      fileReader = new FileReader(f);
      bufferedReader = new BufferedReader(fileReader);
      String initial = bufferedReader.readLine();
      count = Integer.parseInt(initial);
    } catch (Exception ex) {
      if (writer !=null){
        writer.close();
      }
    }
    if (bufferedReader != null) {
      try {
        bufferedReader.close();
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
    return count;
  }

  public void save(int count) throws Exception {
    FileWriter fileWriter = null;
    PrintWriter printWriter = null;
    fileWriter = new FileWriter("FileCounter.initial");
    printWriter = new PrintWriter(fileWriter);
    printWriter.println(count);

    // Make sure to close the file
    if (printWriter != null) {
      printWriter.close();
    }
  }
}

读取计数器并以纯文本形式写入的FileCounter.java Servlet

package wtp.filecounter.servlets;
import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import wtp.filecounter.dao.FileDao;

/**
 * Servlet implementation class FileCounter
 */
@WebServlet("/FileCounter")
public class FileCounter extends HttpServlet {
  private static final long serialVersionUID = 1L;

  int count;
  private FileDao dao;

  public void init() throws ServletException {
    dao = new FileDao();
    try {
      count = dao.getCount();
    } catch (Exception e) {
      getServletContext().log("An exception occurred in FileCounter", e);
      throw new ServletException("An exception occurred in FileCounter"
          + e.getMessage());
    }
  }

  protected void doGet(HttpServletRequest request,
      HttpServletResponse response) throws ServletException, IOException {
    // Set a cookie for the user, so that the counter does not increate
    // everytime the user press refresh
    HttpSession session = request.getSession(true);
    // Set the session valid for 5 secs
    session.setMaxInactiveInterval(5);
    response.setContentType("text/plain");
    PrintWriter out = response.getWriter();
    if (session.isNew()) {
      count++;
    }
    out.println("This site has been accessed " + count + " times.");
  }

  public void destroy() {
    super.destroy();
    try {
      dao.save(count);
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0">
  <display-name>wtp.filecounter</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
</web-app>

有什么问题的主意吗？

当我在服务器上运行时，项目打开为“ http：// localhost：8080 / wtp.filecounter /”，而不是“ http：// localhost：8080 / wtp.filecounter / FileCounter”，第二个URL有效

最佳答案

您的servlet被映射到/FileCounter（这就是@WebServlet("/FileCounter")注释所做的）。它是Web应用程序的一部分，部署在某些上下文路径下（假设上下文路径为/myFirstWebApp）。因此，调用servlet的URL是：

http://localhost:8080/myFirstWebApp/FileCounter

关于tomcat - Servlet 3.0 HTTP 404-请求的资源()不可用，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/13430990/