项目实战之使用Servlet+JSP+XML(EL表达式版)实现联系人功能

首先我们应该用对其分包，如下图

首先，我们先创建一个Contact实体类

package cn.qblank.entity;public class Contact {private String id;private String name;private int age;private String gender;private String qq;private String phone;private String address;public String getPhone() {return phone;}public void setPhone(String phone) {this.phone = phone;}public String getId() {return id;}public void setId(String id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public String getGender() {return gender;}public void setGender(String gender) {this.gender = gender;}public String getQq() {return qq;}public void setQq(String qq) {this.qq = qq;}public String getAddress() {return address;}public void setAddress(String address) {this.address = address;}public Contact(String id, String name, int age, String gender, String qq,String address) {super();this.id = id;this.name = name;this.age = age;this.gender = gender;this.qq = qq;this.address = address;}public Contact() {super();}@Overridepublic String toString() {return "Contact [id=" + id + ", name=" + name + ", age=" + age+ ", gender=" + gender + ", qq=" + qq + ", address=" + address+ "]";}}

然后建立一个contact.xml在F盘

写一个XMLUtil类对xml的优化xml的读取和修改

package cn.qblank.utl;import java.io.File;import java.io.FileOutputStream;import org.dom4j.Document;import org.dom4j.io.OutputFormat;import org.dom4j.io.SAXReader;import org.dom4j.io.XMLWriter;public class XMLUtil {/** * 获取结点 * @return * @throws Exception */public static Document getDocuement() throws Exception{return new SAXReader().read(new File("F:/contact.xml"));}/** * 写入文档 */public static void writeXml(Document doc){try {FileOutputStream out = new FileOutputStream("F:/contact.xml");OutputFormat format = OutputFormat.createPrettyPrint();format.setEncoding("utf-8");XMLWriter writer = new XMLWriter(out,format);writer.write(doc);writer.close();} catch (Exception e) {e.printStackTrace();throw new RuntimeException(e);}}}

下面开始写dao层的代码

先实现一个查询所有联系人的功能

@Overridepublic List<Contact> listAllContact() throws Exception {Document doc = XMLUtil.getDocuement();List<Contact> list = new ArrayList<>();@SuppressWarnings("unchecked")List<Element> contactList= (List<Element>)doc.selectNodes("//contact");for (Element elem : contactList) {Contact contact = new Contact();contact.setId(elem.attributeValue("id"));contact.setName(elem.elementText("name"));contact.setAge(Integer.parseInt(elem.elementText("age")));contact.setGender(elem.elementText("gender"));contact.setQq(elem.elementText("qq"));contact.setPhone(elem.elementText("phone"));contact.setAddress(elem.elementText("address"));list.add(contact);}return list;}

对应的Servlet（接收数据）代码和Jsp(显示界面)代码如下

public class AddContactServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {req.setCharacterEncoding("utf-8");resp.setContentType("text/html;charset=utf-8");resp.setCharacterEncoding("utf-8");//获取参数String name = req.getParameter("c_name");int age = Integer.parseInt(req.getParameter("c_age"));String gender = req.getParameter("c_gender");String qq = req.getParameter("c_qq");String phone = req.getParameter("c_phone");String address = req.getParameter("c_address");Contact contact = new Contact();contact.setName(name);contact.setAge(age);contact.setGender(gender);contact.setQq(qq);contact.setPhone(phone);contact.setAddress(address);ContactDaoImpl contactDaoImpl = new ContactDaoImpl();contactDaoImpl.addContact(contact);resp.sendRedirect(req.getContextPath() + "/ListContactServlet");}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {doGet(req, resp);}}

JSP代码如下:

<%@ page language="java" import="java.util.*,cn.qblank.entity.*"  pageEncoding="UTF-8"%><%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <base href="<%=basePath%>">        <title>联系人列表</title>    <meta http-equiv="pragma" content="no-cache"><meta http-equiv="cache-control" content="no-cache"><meta http-equiv="expires" content="0">    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="This is my page">  </head>  <style>  body{  text-align:center;  }    table{  width:1000px;  text-align:center;  margin: 0 auto;  }  </style>  <body>  <h1>查询所有联系人</h1>  <table border="1" cellspacing="0">   <tr>  <th>编号</th>  <th>姓名</th>  <th>年龄</th>  <th>性别</th>  <th>qq</th>  <th>phone</th>  <th>address</th>  <th colspan="2">操作</th>  </tr>  <!-- 接收到ListContactServlet发过来的信息 -->   <c:forEach items="${contacts}" var="contact">   <c:if test="${!empty contact}">   <tr>   <td>${contact.id}</td>   <td>${contact.name }</td>   <td>${contact.age }</td>   <td>${contact.gender}</td>   <td>${contact.qq}</td>   <td>${contact.phone}</td>   <td>${contact.address}</td>   <td><a href="/ContactProject/QueryContactServlet?id=${contact.id}">修改</a></td>   <td><a href="/ContactProject/DeleteContactServlet?id= ${contact.id}">删除</a></td>   </tr>   </c:if>   </c:forEach>         <tr>    <td colspan="9" align="center"><a href="add_contact.html">[添加联系人]</a></td>    </tr>  </table>    </body></html>

然后再实现一个增加联系人的功能,我们使用UUID的randomUUID方法产生唯一id

public void addContact(Contact contact) {File file = new File("F://contact.xml");Document doc = null;Element rootElem = null;try {if (!file.exists()) {doc = DocumentHelper.createDocument();rootElem = doc.addElement("contactList");}else{doc = XMLUtil.getDocuement();rootElem = doc.getRootElement();}//添加联系人Element contactElem = rootElem.addElement("contact");/** * UUid */String uuid = UUID.randomUUID().toString().replace("-", "");contactElem.addAttribute("id", uuid);contactElem.addElement("name").setText(contact.getName());contactElem.addElement("age").setText(contact.getAge()+"");contactElem.addElement("gender").setText(contact.getGender());contactElem.addElement("qq").setText(contact.getQq());contactElem.addElement("phone").setText(contact.getPhone());contactElem.addElement("address").setText(contact.getAddress());//写入文档XMLUtil.writeXml(doc);} catch (Exception e) {e.printStackTrace();}}

然后写一个add_contact.html页面,显示添加联系人的界面

<style>      table{  margin:0 auto;  }    table tr td{  margin-left:20px;  }    h1{  text-align:center;  }  </style>  <body>  <h1>添加联系人</h1>  <form action="/ContactProject/AddContactServlet"  method="post">  <table border="1">  <tr>  <td>姓名</td>  <td><input type="text" name="c_name"/></td>  </tr>  <tr>  <td>年龄</td>  <td><input type="text" name="c_age"/></td>  </tr>  <tr>  <td>性别</td>  <td>  男<input type="radio" name="c_gender"/>  女<input type="radio" name="c_gender"/>  </td>  </tr>  <tr>  <td>qq</td>  <td><input type="text" name="c_qq"/></td>  </tr>  <tr>  <td>电话</td>  <td><input type="text" name="c_phone"/></td>  </tr>  <tr>  <td>地址</td>  <td><input type="text" name="c_address"/></td>  </tr>  <tr>  <td colspan="2" style="text-align:center">  <input type="submit" value="保存"/>  <input type="reset" value="重置"/>  </td>  </tr>  </table>  </form>  </body>

然后对应的写一个Servlet用于接收用户输入的信息，并调用dao层的添加方法，将其输入的信息导入xml中

public class AddContactServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {req.setCharacterEncoding("utf-8");resp.setContentType("text/html;charset=utf-8");resp.setCharacterEncoding("utf-8");//获取参数String name = req.getParameter("c_name");int age = Integer.parseInt(req.getParameter("c_age"));String gender = req.getParameter("c_gender");String qq = req.getParameter("c_qq");String phone = req.getParameter("c_phone");String address = req.getParameter("c_address");Contact contact = new Contact();contact.setName(name);contact.setAge(age);contact.setGender(gender);contact.setQq(qq);contact.setPhone(phone);contact.setAddress(address);ContactDaoImpl contactDaoImpl = new ContactDaoImpl();contactDaoImpl.addContact(contact);resp.sendRedirect(req.getContextPath() + "/ListContactServlet");}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {doGet(req, resp);}}

下面是删除功能，删除功能最重要的一点是获取id,那么怎么才能获取到id呢，我们可以在主界面contact_list.jsp的删除链接跳转时将id这个参数传入过去,如上contact_list.jsp

<td><a href="/ContactProject/DeleteContactServlet?id= <%=contact.getId().trim() %>">删除</a></td>

然后对应的Servlet接收这个id

public class DeleteContactServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {ContactDaoImpl contactDaoImpl = new ContactDaoImpl();String id = req.getParameter("id");contactDaoImpl.deleteContact(id);resp.sendRedirect(req.getContextPath() + "/ListContactServlet");}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {doGet(req, resp);}}

然后在dao层，将对应的联系人删除

@Overridepublic void deleteContact(String id) {Document doc = null;try {doc = XMLUtil.getDocuement();Element contactElem = (Element) doc.selectSingleNode("//contact[@id='"+id.trim()+"']");if (contactElem != null) {contactElem.detach();}XMLUtil.writeXml(doc);} catch (Exception e) {e.printStackTrace();}}

接下来，就是修改的操作，该操作同样需要拿到id，我们也可以用同样的方式接收id

<td><a href="/ContactProject/QueryContactServlet?id=<%=contact.getId()%>">修改</a></td>

由于原本的数据不能变，所以我们需要将原本的数据先查出来，然后才能继续进行修改

@Overridepublic Contact findById(String id) {Document doc = null;Contact c = null;try {doc = XMLUtil.getDocuement();Element contactElem = (Element)doc.selectSingleNode("//contact[@id='"+id+"']");if (contactElem != null) {c  = new Contact();c.setId(contactElem.attributeValue("id"));c.setName(contactElem.elementText("name"));c.setAge(Integer.parseInt(contactElem.elementText("age")));c.setGender(contactElem.elementText("gender"));c.setQq(contactElem.elementText("qq"));c.setPhone(contactElem.elementText("phone"));c.setAddress(contactElem.elementText("address"));}} catch (Exception e) {e.printStackTrace();}return c;}

然后写一个QueryContactServlet用于接收查到的数据

public class QueryContactServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {req.setCharacterEncoding("utf-8");resp.setContentType("text/html;charset=utf-8");resp.setCharacterEncoding("utf-8");String id = req.getParameter("id").trim();//通过id查询到联系人ContactDaoImpl contactDaoImpl = new ContactDaoImpl();Contact contact = contactDaoImpl.findById(id);req.setAttribute("contact", contact);req.getRequestDispatcher("update_contact.jsp").forward(req, resp);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {doGet(req, resp);}}

接下来就是用update_contact.jsp，显示原来的数据

<style>  table{  margin:0 auto;  }    table tr td{  margin-left:20px;  }    h1{  text-align:center;  }  </style>  <body>    <h1>修改联系人</h1>          <form action="/ContactProject/UpdateContactServlet" method="post">  <%    Contact contact = (Contact)request.getAttribute("contact");     %>      <input type="hidden" name="id" value="${contact.id}">  <table border="1">  <tr>  <td>姓名</td>  <td><input type="text" name="c_name" value="${contact.name}"/></td>  </tr>  <tr>  <td>年龄</td>  <td><input type="text" name="c_age" value="${contact.age}"/></td>  </tr>  <tr>  <td>性别</td>  <td>  男<input type="radio" name="c_gender" value="男" <c:if test="${contact.gender == '男'}">checked</c:if> />  女<input type="radio" name="c_gender" value="女" <c:if test="${contact.gender == '女'}">checked</c:if> />  </td>  </tr>  <tr>  <td>qq</td>  <td><input type="text" name="c_qq" value="${contact.qq}"/></td>  </tr>  <tr>  <td>电话</td>  <td><input type="text" name="c_phone" value="${contact.phone}"/></td>  </tr>  <tr>  <td>地址</td>  <td><input type="text" name="c_address" value="${contact.address}"/></td>  </tr>  <tr>  <td colspan="2" style="text-align:center">  <input type="submit" value="保存"/>  <input type="reset" value="重置"/>  </td>  </tr>  </table>  </form>  </body>

接下来根据   用户修改的数据进行修改,方法和添加类似

public class UpdateContactServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {req.setCharacterEncoding("utf-8");resp.setContentType("text/html;charset=utf-8");resp.setCharacterEncoding("utf-8");//获取参数String id = req.getParameter("id");String name = req.getParameter("c_name");int age = Integer.parseInt(req.getParameter("c_age"));String gender = req.getParameter("c_gender");String qq = req.getParameter("c_qq");String phone = req.getParameter("c_phone");String address = req.getParameter("c_address");Contact contact = new Contact();contact.setId(id);contact.setName(name);contact.setAge(age);contact.setGender(gender);contact.setQq(qq);contact.setPhone(phone);contact.setAddress(address);ContactDaoImpl contactDaoImpl = new ContactDaoImpl();contactDaoImpl.updateContact(contact);//3.跳转到查询联系人的页面resp.sendRedirect(req.getContextPath()+"/ListContactServlet");}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {doGet(req, resp);}}

对应的dao层修改数据

@Overridepublic void updateContact(Contact contact) {Document doc = null;try {doc = XMLUtil.getDocuement();Element contactElem = (Element) doc.selectSingleNode("//contact[@id='"+contact.getId()+"']");contactElem.element("name").setText(contact.getName());contactElem.element("age").setText(contact.getAge()+"");contactElem.element("gender").setText(contact.getGender());contactElem.element("qq").setText(contact.getQq());contactElem.element("phone").setText(contact.getPhone());contactElem.element("address").setText(contact.getAddress());//写入文档XMLUtil.writeXml(doc);} catch (Exception e) {e.printStackTrace();}}

这样，我们利用xml实现增删改查的功能就实现了，总结一点

在这个我们用到了Servlet，JSP，XMl技术,EL表达式

Servlet：用于接收数据，并处理逻辑

JSP :     用于显示界面,和用户进行交互,在jsp中尽量少写java代码

XML :  用于存储数据，实现持久化数据，类似于数据库。