getResource() nullPointerException

Question

我正在尝试用Java获取本地JSON文件的内容。相反，我得到了以下堆栈跟踪：

java.lang.NullPointerException
    fi.avaliaho.ottoautomaatitv2.Webservice.doGet(Webservice.java:24)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
    org.apache.catalina.filters.CorsFilter.handleNonCORS(CorsFilter.java:352)
    org.apache.catalina.filters.CorsFilter.doFilter(CorsFilter.java:171)

我已经确保文件coordinates.json与Webservice.java文件位于相同的目录中。我知道this question，但答案并不能解决我的问题。下面是我的servlet：

import java.net.URL;
import java.io.*;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Webservice extends HttpServlet {

    URL path = null;
    Reader file = null;
    BufferedReader input = null;

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        path = Webservice.class.getResource("coordinates.json");
        file = new FileReader(path.getFile());
    }
}

Answer 1

尝试使用getSystemResource()方法

path = ClassLoader.getSystemResource("coordinates.json")

或者@LaksithaRanasingha是如何在开头添加/的评论中提到的：

path = Webservice.class.getResource("/coordinates.json");

这也可能是有用的Class.getResource and ClassLoader.getSystemResource: is there a reason to prefer one to another?