明明硬盘中存在users.xml，但是提示：系统找不到指定的路径。

解决办法：

设置String的编码格式

 realpath = URLDecoder.decode(realpath, "UTF-8");

源代码：

 package cn.itcast.utils;

 import java.io.File;

 import java.io.FileOutputStream;

 import java.io.IOException;

 import java.io.UnsupportedEncodingException;

 import java.net.URL;

 import java.net.URLDecoder;

 import org.dom4j.Document;

 import org.dom4j.DocumentException;

 import org.dom4j.io.OutputFormat;

 import org.dom4j.io.SAXReader;

 import org.dom4j.io.XMLWriter;

 public class XmlUtils {

     private static String filename = "users.xml";

     public static Document getDocument() throws DocumentException, UnsupportedEncodingException {

         URL url = XmlUtils.class.getClassLoader().getResource(filename);

         String realpath = url.getPath();

         realpath = URLDecoder.decode(realpath, "UTF-8");

         SAXReader reader = new SAXReader();

         return reader.read(new File(realpath));

     }

     public static void write2Xml(Document document) throws IOException {

         URL url = XmlUtils.class.getClassLoader().getResource(filename);

         String realpath = url.getPath();

         realpath = URLDecoder.decode(realpath, "UTF-8");

         OutputFormat format = OutputFormat.createPrettyPrint();

         XMLWriter writer = new XMLWriter(new FileOutputStream(realpath), format);

         writer.write(document);

         writer.close();

     }

 }

HTTP Status 500 – Internal Server Error

Type Exception Report

Message org.dom4j.DocumentException: C:\Program%20Files\Apache%20Software%20Foundation\Tomcat%208.5\webapps\day09_user\WEB-INF\classes\users.xml (系统找不到指定的路径。) Nested exception: C:\Program%20Files\Apache%20Software%20Foundation\Tomcat%208.5\webapps\day09_user\WEB-INF\classes\users.xml (系统找不到指定的路径。)

Description The server encountered an unexpected condition that prevented it from fulfilling the request.

Exception

java.lang.RuntimeException: org.dom4j.DocumentException: C:\Program%20Files\Apache%20Software%20Foundation\Tomcat%208.5\webapps\day09_user\WEB-INF\classes\users.xml (系统找不到指定的路径。) Nested exception: C:\Program%20Files\Apache%20Software%20Foundation\Tomcat%208.5\webapps\day09_user\WEB-INF\classes\users.xml (系统找不到指定的路径。)

	cn.itcast.dao.impl.UserDaoXmlImpl.find(UserDaoXmlImpl.java:35)

	cn.itcast.service.impl.BusinessServiceImpl.loginUser(BusinessServiceImpl.java:29)

	cn.itcast.web.controller.LoginServlet.doGet(LoginServlet.java:23)

	cn.itcast.web.controller.LoginServlet.doPost(LoginServlet.java:38)

	javax.servlet.http.HttpServlet.service(HttpServlet.java:661)

	javax.servlet.http.HttpServlet.service(HttpServlet.java:742)

	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

Root Cause

org.dom4j.DocumentException: C:\Program%20Files\Apache%20Software%20Foundation\Tomcat%208.5\webapps\day09_user\WEB-INF\classes\users.xml (系统找不到指定的路径。) Nested exception: C:\Program%20Files\Apache%20Software%20Foundation\Tomcat%208.5\webapps\day09_user\WEB-INF\classes\users.xml (系统找不到指定的路径。)

	org.dom4j.io.SAXReader.read(SAXReader.java:266)

	cn.itcast.utils.XmlUtils.getDocument(XmlUtils.java:28)

	cn.itcast.dao.impl.UserDaoXmlImpl.find(UserDaoXmlImpl.java:18)

	cn.itcast.service.impl.BusinessServiceImpl.loginUser(BusinessServiceImpl.java:29)

	cn.itcast.web.controller.LoginServlet.doGet(LoginServlet.java:23)

	cn.itcast.web.controller.LoginServlet.doPost(LoginServlet.java:38)

	javax.servlet.http.HttpServlet.service(HttpServlet.java:661)

	javax.servlet.http.HttpServlet.service(HttpServlet.java:742)

	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

Note The full stack trace of the root cause is available in the server logs.

Apache Tomcat/8.5.24