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在添加时，添加新的数据，而是又重复添加xml里面的数据，这是为什么?

来源：5-3 项目作业

慕帅5138158

2021-04-01 13:26:06

问题描述：

在添加时，添加新的数据，而是又重复添加xml里面的数据，这是为什么?

相关代码：

ManagementController:

package com.pre.library.controller;

import java.io.File;
import java.io.IOException;
import java.util.List;
import java.util.UUID;

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 org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileItemFactory;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

import com.pre.library.entity.Books;
import com.pre.library.service.BookService;

/**
 * Servlet implementation class ManagementController
 */
@WebServlet("/management")
public class ManagementController extends HttpServlet {
	private static final long serialVersionUID = 1L;
    private  BookService bookService=new BookService(); 
    /**
     * @see HttpServlet#HttpServlet()
     */
    public ManagementController() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		response.setContentType("text/html;charset=utf-8");
		String method = request.getParameter("method");
		if ("bookList".equals(method)) {
			this.list(request, response);
		}else if ("show_addBook".equals(method)) {
			this.addBook(request, response);
	    } else if ("createBook".equals(method)) {
	    	   this.createBook(request, response);
	    } 
	}
	//图书展示
	private void list(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		 List<Books> list = bookService.bookList();
		request.setAttribute("bookList", list);
		request.getRequestDispatcher("/WEB-INF/jsp/bookList.jsp").forward(request, response);
	}
	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}
	//显示新增页面
		private void addBook(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
			request.getRequestDispatcher("/WEB-INF/jsp/addBook.jsp").forward(request, response);		
		}
	//新增图书信息
	private void createBook(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//1. 初始化FileUpload组件
		FileItemFactory factory = new DiskFileItemFactory();
		/**
		 * FileItemFactory 用于将前端表单的数据转换为一个个FileItem对象
		 * ServletFileUpload 则是为FileUpload组件提供Java web的Http请求解析
		 */
		ServletFileUpload sf = new ServletFileUpload(factory);
		//2.遍历所有FileItem
		try {
			List<FileItem>formData=sf.parseRequest(request);
			Books book=new Books();
			for(FileItem fi:formData) {
				if(fi.isFormField()) {
					System.out.println("普通输入项:" + fi.getFieldName() + ":" + fi.getString("UTF-8"));
					switch (fi.getFieldName()) {
					case "bookId":
						book.setBookId(Integer.parseInt(fi.getString("UTF-8")));
						break;
					case "bookName":
						book.setBookName(fi.getString("UTF-8"));
						break;
					case "categoryId":
						book.setCategoryId(fi.getString("UTF-8"));
						break;
					case "bookPrice":
						book.setBookPrice(Integer.parseInt(fi.getString("UTF-8")));
						break;
					case "remarks":
						book.setRemarks(fi.getString("UTF-8"));
						break;
					default:
						break;
					}
				}else {
					System.out.println("文件上传项:" + fi.getFieldName());
					//3.文件保存到服务器目录
					String path = request.getServletContext().getRealPath("/upload");
					System.out.println("上传文件目录:" + path);
					//String fileName = "test.jpg";
					String fileName = UUID.randomUUID().toString();
					//fi.getName()得到原始文件名,截取最后一个.后所有字符串,例如:wxml.jpg->.jpg
					String suffix = fi.getName().substring(fi.getName().lastIndexOf("."));
					//fi.write()写入目标文件
					fi.write(new File(path,fileName + suffix));
					book.setBookPic("/upload/" + fileName + suffix);
				}
			}
			bookService.addBook(book);
			response.sendRedirect("/management?method=bookList");//返回列表页
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();

		}



	}
}

相关代码：

BookDao:

package com.pre.library.dao;

import java.util.List;

import com.pre.library.entity.Books;
import com.pre.library.utils.XmlDataSource;

public class BookDao {
	//图书信息的展示，通过XmlDataSource文件进行读取
	public List<Books> bookList() {
		List<Books> bookList = XmlDataSource.bookData();
		return bookList;
	}
	//图书添加
	public void addBook(Books book) {
		XmlDataSource.appendBook(book);
	}
}

相关代码：

Books:

package com.pre.library.entity;
/**
 * 1.类型描述:图书id,图书名，图书分类，价格，图书封面,备注
 * @author zhanzhimin
 *
 */
public class Books {
	private Integer bookId;//图书id
	private String bookName;//图书名
	private String categoryId;//图书分类分类1-计算机2-软件工程
	private Integer bookPrice;//价格
	private String bookPic;//图书封面
	private String remarks;//备注
	public Integer getBookId() {
		return bookId;
	}
	public void setBookId(Integer bookId) {
		this.bookId = bookId;
	}
	public String getBookName() {
		return bookName;
	}
	public void setBookName(String bookName) {
		this.bookName = bookName;
	}
	public String getCategoryId() {
		return categoryId;
	}
	public void setCategoryId(String categoryId) {
		this.categoryId = categoryId;
	}
	public Integer getBookPrice() {
		return bookPrice;
	}
	public void setBookPrice(Integer bookPrice) {
		this.bookPrice = bookPrice;
	}
	public String getBookPic() {
		return bookPic;
	}
	public void setBookPic(String bookPic) {
		this.bookPic = bookPic;
	}
	public String getRemarks() {
		return remarks;
	}
	public void setRemarks(String remarks) {
		this.remarks = remarks;
	}


}

相关代码：

BookService:

package com.pre.library.service;

import java.util.List;

import com.pre.library.dao.BookDao;
import com.pre.library.entity.Books;


public class BookService {
	private BookDao bookDao=new BookDao();
	//图书的展示
	public List<Books> bookList() {
		/*List<Books> bookList = XmlDataSource.bookData();
		return bookList;*/
		return bookDao.bookList();
	}
	//图书添加
	public void addBook(Books book) {
		bookDao.addBook(book);
	}
	public static void main(String[] arge) {
		BookService bookService=new BookService();
		List<Books> booklist=bookService.bookList();
		for(Books books:booklist) {
			System.out.println(books.getBookName());
		}
	}
}

相关代码：

XmlDataSource:

package com.pre.library.utils;



import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.net.URLDecoder;
import java.util.ArrayList;
import java.util.List;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;

import com.pre.library.entity.Books;

/**
 * 数据源类，用于XML文件解析为Java对象
 * 
 * @author zhanzhimin
 */
public class XmlDataSource {
	private static List<Books> data = new ArrayList<Books>();
	private static String dataFile;
	static {
		// painting.xml文件完整物理地址
		// c:\new style\book.xml
		// c:\new%20style\book.xml
		dataFile = XmlDataSource.class.getResource("/book.xml").getPath();
		reloadBooks();
	}

	public static void reloadBooks() {
		// 通过URLDecoder类将Base64转换成普通字符窜
		URLDecoder decoder = new URLDecoder();
		try {
			dataFile = decoder.decode(dataFile, "utf-8");
			System.out.println(dataFile);
			// 利用dom4j对xml解析
			SAXReader reader = new SAXReader();
			Document document = reader.read(dataFile);
			List<Node> list = document.selectNodes("/root/book");
			for (Node node : list) {
				Element element = (Element) node;
				String bookId = element.elementText("bookId");
				String bookName = element.elementText("bookName");
				Books book = new Books();
				book.setBookId(Integer.parseInt(bookId));
				book.setBookName(bookName);
				book.setCategoryId(element.elementText("categoryId"));
				book.setBookPrice(Integer.parseInt(element.elementText("bookPrice")));
				book.setBookPic(element.elementText("bookPic"));
				book.setRemarks(element.elementText("remarks"));
				data.add(book);
				System.out.println(bookId + ":" + bookName);
			}

		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	/**
	 * 添加图书的信息
	 * @param 实体对象Books book
	 * 
	 */
	public static void appendBook(Books book) {
		//通过SAXReader读取xml文档，得到Document
		SAXReader reader=new SAXReader();
		Writer writer=null;
		try {
			Document document=reader.read(dataFile);
			//2.创建book.xml的book节点
			Element root=document.getRootElement();
			Element b=root.addElement("book");
			//3.创建各个节点
			b.addElement("bookId").setText(book.getBookId().toString());
			b.addElement("bookName").setText(book.getBookName());
			b.addElement("categoryId").setText(book.getCategoryId());
			b.addElement("bookPrice").setText(book.getBookPrice().toString());
			b.addElement("bookPic").setText(book.getBookPic());
			b.addElement("remarks").setText(book.getRemarks());
			//4.完成追加，写入xml
			writer=new OutputStreamWriter(new FileOutputStream(dataFile),"UTF-8");
			document.write(writer);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			if(writer!=null) {
				try {
					writer.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			reloadBooks() ;
		}
	}
	public static List<Books> bookData() {
		return data;

	}
	public static void main(String[] args) {
		/*new XmlDataSource();
		List<Books> bk=XmlDataSource.bookData();
		System.out.println(bk);*/
		/*Books b=new Books();
		b.setBookId(1000);
		b.setBookName("软件更新");
		b.setCategoryId("计算机");
		b.setBookPrice(100);
		b.setBookPic("/image/g1.jpg");
		b.setRemarks("测试");
		XmlDataSource.appendBook(b);*/
	}
}

相关代码：

addBook.jsp:

<%@page contentType="text/html;charset=utf-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>新建图书信息</title>
<link rel="stylesheet" href="css/bootstrap.min.css">
<link rel="stylesheet" href="css/add.css">
<script type="text/javascript" href="js/validation.js"></script>
<script>
       function submit() {
           var a = checkEmpty("#bookId");
           var b = checkEmpty('#bookName');
           var c = checkCategory('#categoryId');
           var d = checkPrice('#bookPrice');
           var e = checkFile('#bookPic');
           var f = checkEmpty('#remarks');
           if (a && b && c && d && e && f)) {
             return true;
           } else {
             return false;
           }
}
</script>
</head>
<body>
	<nav class="navbar navbar-default">
		<div class="container">
			<div class="navbar-header">
				<a class="navbar-brand" href="/dept/list.do"> 图书信息管理 </a>
			</div>
		</div>
	</nav>
	<div class="container">
		<div class="jumbotron">
			<h1>Hello,${sessionScope.user.userName}!</h1>
			<p>请小心地新增图书信息，要是建了一个错误的就不好了。。。</p>
		</div>
		<div class="page-header">
			<h3>
				<small>新建</small>
			</h3>
		</div>
		<form class="form-horizontal" action="/management?method=createBook"
			method="post" enctype="multipart/form-data"
			onsubmit="return submit()">

			<div class="form-group">
				<label for="name" class="col-sm-2 control-label">图书编号 ：</label>
				<div class="col-sm-8">
					<input name="bookId" class="form-control" id="bookId"
						onblur="checkEmpty('#bookId')">
				</div>
			</div>
			<div class="form-group">
				<label for="name" class="col-sm-2 control-label">图书名称 ：</label>
				<div class="col-sm-8">
					<input name="bookName" class="form-control" id="bookName"
						onblur="checkEmpty('#bookName')">
				</div>
			</div>
			<div class="form-group">
				<label for="categoryId" class="col-sm-2 control-label">分类 ：</label>
				<select id="categoryId" name="categoryId"
					class="col-sm-2 form-control"
					onchange="checkCategory('#categoryId')"
					style="width: auto; margin-left: 15px">
					<option value="ca001" selected="">计算机</option>
					<option value="ca0002">文学</option>
					<option value="ca0003">历史</option>
					<!-- 下拉列表的内容要从分类中进行读取，value值是分类id -->
				</select>
			</div>

			<div class="form-group">
				<label for="name" class="col-sm-2 control-label">价格 ：</label>
				<div class="col-sm-8">
					<input name="bookPrice" class="form-control" id="bookPrice"
						onblur="checkPrice('#bookPrice')">
				</div>
			</div>

			<div class="form-group">
				<label for="name" class="col-sm-2 control-label">图书封面 ：</label> <input
					type="file" id="bookPic" name="bookPic" style="padding-left: 15px"
					accept="image/*" onchange="checkFile('#bookPic')">
			</div>

			<div class="form-group">
				<label for="name" class="col-sm-2 control-label">备注 ：</label>
				<div class="col-sm-8">
					<input name="remarks" class="form-control" id="remarks"
						onblur="checkEmpty('#remarks')">
				</div>
			</div>

			<div class="form-group">
				<div class="col-sm-offset-2 col-sm-10">
					<button type="submit" class="btn btn-primary">保存</button>
					&nbsp;&nbsp;&nbsp;
				</div>
			</div>
		</form>
	</div>
	<footer class="text-center"> copy@imooc </footer>
</body>
</html>

相关代码：

bookList.jsp:

<%@page contentType="text/html;charset=utf-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/fmt"  prefix="fmt"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>图书后台管理</title>
<link rel="stylesheet" href="css/index.css">
<link rel="stylesheet" href="css/bootstrap.min.css">
<script type="text/javascript" href="/js/jquery-3.4.1.js"></script>
</head>

<body>
	<header>
		<div class="container">
			<nav>
				<a href="/management?method=bookList">图书信息管理</a>
			</nav>
			<nav>
				<a href="categoryList.html">分类管理</a>
			</nav>

		</div>
	</header>
	<section class="banner">
		<div class="container">
			<div>
				<h1>图书管理系统</h1>
				<p>图书信息管理</p>
			</div>
		</div>
	</section>
	<section class="main">


		<div class="container">
			<form class="form-horizontal" action="/searchBook" method="post">
				<div class="form-group" style="float: right;">
					<div class="col-sm-offset-2 col-sm-10">
						<button type="submit" class="btn btn-primary">查询</button>
						&nbsp;&nbsp;&nbsp;
					</div>
				</div>
				<div class="form-group" style="float: right; width: 300px;">
					<div class="col-sm-8">
						<input name="searchContent" class="form-control"
							id="searchContent" placeholder="输入要查询的分类" style="width: 250px">
					</div>
				</div>


			</form>
		</div>
		<div class="container">

			<table class="table table-striped">
				<thead>
					<tr>
						<th>序号</th>
						<th>图书编号</th>
						<th>图书名称</th>
						<th>分类</th>
						<th>价格</th>
						<th>图书封面</th>
						<th>操作</th>

					</tr>
				</thead>
				<tbody>
					<c:forEach items="${bookList}" var="bookList" varStatus="idx">
						<tr>
							<td>${idx.index + 1}</td>
							<td>${bookList.bookId}</td>
							<td>${bookList.bookName}</td>
							<td>${bookList.categoryId}</td>
							<td><fmt:formatNumber pattern="￥0.00"
									value="${bookList.bookPrice}"></fmt:formatNumber></td>
							<td><img src="${bookList.bookPic}"></td>
							<td><a href="/management?method=show_updateBook">修改</a> <a
								href="/deleteBook?bookId=book0001">删除</a></td>
							<!--在循环显示数据时，此处的book0001可以用EL表达式进行替换-->

						</tr>
					</c:forEach>
				</tbody>
			</table>
		</div>
	</section>
	<section class="page">
		<div class="container">
			<div id="fatie">
				<a href="/management?method=show_addBook"><button>新建</button></a>
			</div>
		</div>
	</section>
	<footer> copy@慕课网 </footer>
</body>
</html>

相关截图：

服务器：

http://img.mukewang.com/climg/6065592109683b5016130861.jpghttp://img.mukewang.com/climg/6065592109e1870c15600852.jpg

控制台：

http://img.mukewang.com/climg/606558b8095352b011850845.jpg

写回答

1回答

好帮手慕阿慧

2021-04-01

已采纳

同学你好，

1、出现重复数据，是因为reloadBooks()方法中是往data集合中添加xml中的数据。建议同学在添加数据之前 清空data集合。

参考代码如下：

http://img.mukewang.com/climg/606577c8090592de05150302.jpg

2、报Adding text to an XML document must not be null错误，建议同学在提交表单之前看一下数据是否为空。如果为空，则不提交表单。

checkEmpty()方法需要传入两个参数，分别是表单域选择器和错误提示选择器。

参考代码如下：

http://img.mukewang.com/climg/60657cb009e1a13d08220454.jpg

http://img.mukewang.com/climg/60657d0809513c3506960454.jpg

祝学习愉快~

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