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

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

源代码：

 1 package cn.itcast.utils;
 2 
 3 import java.io.File;
 4 import java.io.FileOutputStream;
 5 import java.io.IOException;
 6 import java.io.UnsupportedEncodingException;
 7 import java.net.URL;
 8 import java.net.URLDecoder;
 9 
10 import org.dom4j.Document;
11 import org.dom4j.DocumentException;
12 import org.dom4j.io.OutputFormat;
13 import org.dom4j.io.SAXReader;
14 import org.dom4j.io.XMLWriter;
15 
16 public class XmlUtils {
17 
18     private static String filename = "users.xml";
19 
20     public static Document getDocument() throws DocumentException, UnsupportedEncodingException {
21 
22         URL url = XmlUtils.class.getClassLoader().getResource(filename);
23         String realpath = url.getPath();
24 
25         realpath = URLDecoder.decode(realpath, "UTF-8");
26 
27         SAXReader reader = new SAXReader();
28         return reader.read(new File(realpath));
29     }
30 
31     public static void write2Xml(Document document) throws IOException {
32 
33         URL url = XmlUtils.class.getClassLoader().getResource(filename);
34         String realpath = url.getPath();
35 
36         realpath = URLDecoder.decode(realpath, "UTF-8");
37 
38         OutputFormat format = OutputFormat.createPrettyPrint();
39         XMLWriter writer = new XMLWriter(new FileOutputStream(realpath), format);
40         writer.write(document);
41         writer.close();
42     }
43 }

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