JaveEE之JavaBean

深藏阁楼爱情的钟 2022-06-04 00:09 113阅读 0赞

JavaBeans是特殊的java类，JavaBeans是Java平台的可重用组件，能提供一定的通用功能，可以在Java应用中重复使用，组合使用；JavaBeans组件可以快速生成新的应用

JavaBeas的编码约定包括  
1.一个公有的(public)默认的无参构造函数  
2.需要序列化且实现Serializable接口  
3.所有属性都是私有的(private)  
4.提供一系列公有的Getter和Setter方法  
一、首先创建一个页面，从页面获取用户名和密码

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
    <html>
      <head>
        <base href="<%=basePath%>">
        <title>JavaBean</title>
      </head>
    
      <body>
        <form action="forward.do" method="post">
            用户:<input type="text" name="name" value="${name }"></br>
            密码:<input type="password" name="password" value=""></br>
            <input type="submit" value="提交">
        </form>
      </body>
    </html>

二、再写一个JavaBean，需要序列化且实现Serializable接口

package edu.xt.bean;
    
    import java.io.Serializable;
    
    public class Person implements Serializable{ 
    
        private static final long serialVersionUID = 1L;
    
        private String name;
        private String password;
    
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public String getPassword() {
            return password;
        }
        public void setPassword(String password) {
            this.password = password;
        }
        //默认无参构造器
        public Person() {
            super();
        }
        public Person(String name, String password) {
            super();
            this.name = name;
            this.password = password;
        }
    
    
    }

三、创建一个页面实现Servlet转发

package edu.xt.bean;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.RequestDispatcher;
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    @WebServlet("/forward.do")
    public class ForwardServlet 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 {
            String name = request.getParameter("name");
            String password = request.getParameter("password");
            Person person = new Person();
            person.setName(name);
            person.setPassword(password);
    
            //在属性中设置对象
            request.setAttribute("name", name);
            request.setAttribute("password", password);     
            RequestDispatcher view = request.getRequestDispatcher("result.jsp");
            view.forward(request, response);
        }
    }

四、来一个页面接受结果

<html>
      <head>
        <base href="<%=basePath%>">
        <title>获取请求中的对象</title>
      </head>
      <body>
       <h4>方式二</h4>
       <jsp:useBean id="person" class="edu.xt.bean.Person" scope="page"></jsp:useBean>
       <jsp:setProperty property="name" name="person"/>
       <jsp:setProperty property="password" name="person"/>
    
        获取的人名:<jsp:getProperty property="name" name="person"/>
        获取密码:<jsp:getProperty property="password" name="person"/>
        <hr/>
      </body>
    </html>

启动程序看一下效果：  
![这里写图片描述][SouthEast]  
接收结果的页面  
![这里写图片描述][SouthEast 1]

[SouthEast]: /images/20220604/4ca23e406b214880bda72eea3cfc37d7.png
[SouthEast 1]: /images/20220604/57a3010008874d52abcddf80672f6365.png