在Java Web项目中编译servlet和其他类

Question

ComputerSV.java:13: error: cannot find symbol
        ArrayList<Computer> computers = new ArrayList<>();
                  ^
  symbol:   class Computer
  location: class ComputerSV
ComputerSV.java:15: error: cannot find symbol
            new Computer(
                ^
  symbol:   class Computer
  location: class ComputerSV
ComputerSV.java:25: error: cannot find symbol
            new Computer(
                ^
  symbol:   class Computer
  location: class ComputerSV
3 errors

我的Servlet源代码是：

package com.lcdss.compmng.controller;

import java.io.IOException;
import java.util.ArrayList;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;[Imgur](http://i.imgur.com/D6rN3UA.png)
import javax.servlet.http.HttpServletResponse;

class ComputerSV extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
        ArrayList<Computer> computers = new ArrayList<>();
        computers.add(
            new Computer(
                1,
                "HP",
                "hostname",
                "Windows 10 Pro x64",
                "Intel I7 7700K 4.2 GHz",
                2048,
                8196,
                "Anapolis"
            ),
            new Computer(
                2,
                "DELL",
                "hostname",
                "Windows 10 Home Basic x64",
                "Intel I7 7500U 2.5 GHz",
                512,
                4098,
                "Goiania"
            )
        );

        request.setAttribute("computers", computers);
        request.getRequestDispatcher("computer/index.jsp").forward(request, response);
    }
}

我使用tomcat作为Web服务器，只是一个文本编辑器（Atom）来帮助我完成这个挑战（现在是stackoverflow）。我现在的问题是编译器没有找到我已经编译的类计算机，但没有成功修复这个错误。

Answer 1

我错过了对Computer类的导入，并且在上面的示例中出现了语法错误。

package com.lcdss.compmng.controller;

import java.io.IOException;
import java.util.ArrayList;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.lcdss.compmng.entity.Computer;

public class ComputerSV extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
        ArrayList<Computer> computers = new ArrayList<>();

        computers.add(
            new Computer(
                1,
                "HP",
                "hostname",
                "Windows 10 Pro x64",
                "Intel I7 7700K 4.2 GHz",
                2048,
                8196,
                "Anapolis"
            )
        );

        computers.add(
            new Computer(
                2,
                "DELL",
                "hostname",
                "Windows 10 Home Basic x64",
                "Intel I7 7500U 2.5 GHz",
                512,
                4098,
                "Goiania"
            )
        );

        request.setAttribute("computers", computers);
        request.getRequestDispatcher("computer/index.jsp").forward(request, response);
    }
}

为了编译，我使用了命令javac-cp /opt/tomcat/webapps/compmng/WEB-INF/classes：/opt/tomcat/lib/servlet-api.jarComputerSV. java。第一个类路径（cp）通知编译器我的类在哪里以及包的名称是什么。

Answer 2

它和tomcat没有关系。这是一个正常的编译问题。在编译时间/阶段，当ArrayList