Javaweb开发中三层架构

今天决定拿一个JavaWeb开发中的三层架构作为开始，走起~~随着jsp的简单实用，model1和model2被大家所熟悉，但是这两种设计模式过于繁琐，前者在jsp页面中直接页面又写逻辑（我很喜欢在一个里面一顿狂写~），后者在servlet中既写页面又写逻辑业务，繁琐难以维护(页面和业务逻辑的确分开了，但是长长的代码写在servlet中过于臃肿)，所以引出今天企业中大都用到的开发架构模式----三层架构，三层指的是web层 service层 dao层它这种架构是我们在javaweb开发中经常使用的，个人感觉这三层架构大大减少了类之间的耦合性，大家各司其职，利于维护。

1. Web层:它包含了jsp servlet javaBean相关内容，当作业务流程的跳转，层中可写mvc设计模式，便于人机交互。

2. Service层:它也叫做bussiness层，类似中枢神经的存在关联其他两层，但它只处理业务逻辑操作。

3. Dao层数据层也叫做持久化层（持久化框架）它的主要功能是负责对数据源（解析xml，数据库）访问，简单说，它就是包含对数据的CRUD 操作。

　　　　　　　　流程图

　　　　搭建程序包结构

　　　　jar包

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>系统入口</title>
</head>
<body>
       <h1 align = "center">第一天写博客</h1>
       <div align="center">
       <h2>
       
       <a href="${pageContext.request.contextPath}/login.jsp">登录</a>
       <a href="${pageContext.request.contextPath}/regist.jsp">注册</a>

       </h2>
       </div>
</body>
</html>

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%
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>系统注册</title>

   
</head>

<body>
       <div>
       <c:forEach items="${map}" var="entry">
           ${entry.value}
       </c:forEach>
       ${requestScope["regist.msg"]}
       </div>
        <form action="${pageContext.request.contextPath}/servletregist" method="post">
            <table>
                  <tr>
                      <td>用户名：</td>
                      <td><input type="text" name="username"></td>
                  </tr>

                  <tr>
                      <td>密码：</td>
                      <td><input type="password" name="password"></td>
                  </tr>

                  <tr>
                      <td>再次密码：</td>
                      <td><input type="password" name="repassword"></td>
                  </tr>

                  <tr>
                      <td>生日：</td>
                      <td><input type="text" name="date"></td>
                  </tr>

                  <tr>
                      <td>介绍：</td>
                      <td><input type="text" name="resume"></td>
                  </tr>
                  <tr>
                      <td><input type="submit" value="注册" ></td>
                      <td><input type="reset" value="重置"></td>
                  </tr>

            </table>
        </form>
</body>
</html>

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
   <div>
       ${requestScope["login.msg"]}
   </div>
   <form action="${pageContext.request.contextPath}/servletlogin" method="post">
       <table>
           <tr>
               <td>请输入用户名：</td>
               <td><input type ="text" name="username" value="${cookie.username.value}"></td>
           </tr>
           <tr>
               <td>请输入密码：</td>
               <td><input type ="password" name="password"></td>
           </tr>

           <tr>
               <td>七天内记住密码</td>
               <td><input type="checkbox" name="remember" value="ok"></td>
           </tr>

           <tr>
               <td><input type="submit" value="登陆"></td>
               <td><input type="reset" value="重置"></td>
           </tr>
       </table>
   </form>
</body>
</html>

接着就是web层的servlet

/** 注册*/
public class servletregist extends HttpServlet {

   public void doGet(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {
           doPost(request,response);
   }

   public void doPost(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {
       //设置编码
       request.setCharacterEncoding("utf-8");

　　
      　　//创建user对象
       User user = new User();

       try {
           //设置时间
           ConvertUtils.register(new MyDateConverter(),java.util.Date.class);
           //内省
           BeanUtils.populate(user, request.getParameterMap());

       } catch (IllegalAccessException | InvocationTargetException e) {
           e.printStackTrace();
       }
           //user类的validate，用来判断运行后的值是否为空，在后面
       Map<String, String> map = user.validate();

　　 //如果大于0证明输入有问题
       if (map.size()>0) {
           //输入有误，在request域中存入map
           request.setAttribute("map", map);

　　　　//请求转发到注册界面
           request.getRequestDispatcher("/regist.jsp").forward(request, response);
           return;
       }

　　//创建service层的对象
       UserService us = new UserService();

       try {

           us.regist(user);
            //重定向，到当前项目下的制定文件
           response.sendRedirect(request.getContextPath()+"/login.jsp");

           return;

       } catch (Exception e) {
           e.printStackTrace();

           request.setAttribute("regist.msg", "注册失败");
           //请求转发
           request.getRequestDispatcher("/regist").forward(request, response);

           return;
       }
   }

}

public class servletlogin extends HttpServlet {

   public void doGet(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {
       doPost(request, response);

   }

   public void doPost(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {

　　　　//从页面拿到运行后的值　
       String username = request.getParameter("username");
       String password = request.getParameter("password");

　　　　//
       UserService us = new UserService();
       try {
       User user = us.login(username, password);
           if (user == null) {
               //登陆失败，设置错误信息
               request.setAttribute("login.msg", "用户信息不能为空");
               request.getRequestDispatcher("/login.jsp").forward(request, response);
           }else {
               String remember = request.getParameter("remember");

　　　　　　//如果点击了记住登陆按钮
if ("ok".equals(remember)) {

　　　　　　　　//cookie可以完成记者登陆
Cookie cookie = new Cookie("username", username);

　　　　　　　　//设置保留时间
                   cookie.setMaxAge(7*24*60*60);
                   cookie.setPath("/");
                   response.addCookie(cookie);
               }

               request.getSession().setAttribute("user", user);

               response.sendRedirect(request.getContextPath()+"/hello.jsp");
           }
       } catch (DocumentException e) {

e.printStackTrace();

request.setAttribute("login.msg", "登陆失败");

           request.getRequestDispatcher("/login.jsp").forward(request,
                   response);
           return;
       }

   }
}

还是有一个销毁session的servlet

request.getSession().invalidate();

response.sendRedirect(request.getContextPath()+"/login.jsp");

service层的类中只有两个方法

public void regist(User user) throws DocumentException, IOException{
       UserDao ud = new UserDao();
       ud.add(user);
   }


   public User login(String username,String password) throws DocumentException{

       UserDao ud = new UserDao();

       return ud.read( username, password);
   }

dao层完成业务
public class UserDao {

   public void add(User user) throws DocumentException, IOException {
       // 使用dom4j来完成对users.xml操作
       // 1.获取Document对象
       Document document = Dom4JUtils.getDocument("E:/Users.xml");

       // 2.添加操作
       StringBuilder builder = new StringBuilder();
       builder.append("<user>");
       builder.append("<username>").append(user.getUsername())
               .append("</username>");
       builder.append("<password>").append(user.getPassword())
               .append("</password>");
       builder.append("<birthday>")
               .append(DateUtils.dateToString(user.getDate()))
               .append("</birthday>");
       builder.append("<resume>").append(user.getResume()).append("</resume>");
       builder.append("</user>");
       String xml = builder.toString();

       Document doc = DocumentHelper.parseText(xml);

       document.getRootElement().add(doc.getRootElement());

       // 3.回写
       Dom4JUtils.documentToXml(document, "E:/Users.xml");
   }

   public User read(String username, String password) throws DocumentException {

       // 使用dom4j来完成对users.xml操作
       // 1.获取Document对象
       Document document = Dom4JUtils.getDocument("E:/Users.xml");

       // 2.得到根元素
       Element root = document.getRootElement();

       // 3.得到根下所有user元素
       List<Element> users = root.elements();

       // 4.遍历users
       for (Element user : users) {

           // 5.判断每一个user下的username,password元素中的内容与传递的参数username,password是否相等。如果相等了将user对象信息封装，并返回。
           String usernameElementText = user.elementText("username");


           String passwordElementText = user.elementText("password");

           if (username.equals(usernameElementText)

                   && password.equals(passwordElementText)) {


               User existUser = new User();
               existUser.setUsername(username);
               existUser.setPassword(password);
               existUser.setResume(user.elementText("resume"));
               existUser.setDate(DateUtils.stringToDate(user
                       .elementText("birthday")));
               return existUser;
           }

       }

       return null;
   }

}
bean实体类

public class User {
   private String username;
   private String password;
   private Date date;
   private String resume;
   public User() {
       super();
       // TODO Auto-generated constructor stub
   }
   public User(String username, String password, Date date, String resume) {
       super();
       this.username = username;
       this.password = password;
       this.date = date;
       this.resume = resume;
   }
   public String getUsername() {
       return username;
   }
   public void setUsername(String username) {
       this.username = username;
   }
   public String getPassword() {
       return password;
   }
   public void setPassword(String password) {
       this.password = password;
   }
   public Date getDate() {
       return date;
   }
   public void setDate(Date date) {
       this.date = date;
   }
   public String getResume() {
       return resume;
   }
   public void setResume(String resume) {
       this.resume = resume;
   }

   public Map<String,String> validate(){
       Map<String, String> m = new HashMap<String, String>();
       if (username == null || username.trim().length() == 0) {
           m.put("username.msg", "用户不能为空");
       }
       if (password == null || password.trim().length() == 0) {
           m.put("password.msg", "密码不能为空");
       }
       if (date == null) {
           m.put("date.msg", "生日不能为空");
       }
       if (resume == null || resume.trim().length() == 0) {
           m.put("resume.msg", "介绍不能为空");
       }

       return m;

   }

}

工具类没写用的是dom4j的，感觉很low，先到这，夜深睡觉，分享手感，大神勿喷，

posted @ 2016-09-23 22:51 何koo 阅读(1422) 评论(0) 收藏举报

刷新页面返回顶部

何koo

这个地方可以放置超链接

Javaweb开发中三层架构

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