day 105 - javaBean

javaBean

是一种实体类

JavaBean有特定的写法

必须有一个无参构造
属性必须私有化
必须有对应的get，set方法

一般用来和数据库字段做映射：ORM

ORM：对象关系映射

表-->类
字段-->属性
行记录-->对象

实现

创建数据库，

创建对应实体类

//实体类，和数据库中的表结构一一对应
 public class People {
     private int id;
     private String name;
     private int age;
     private String address;
 
     public People(int id, String name, int age, String address) {
         this.id = id;
         this.name = name;
         this.age = age;
         this.address = address;
     }
 
     public int getId() {
         return id;
     }
 
     public void setId(int 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 getAddress() {
         return address;
     }
 
     public void setAddress(String address) {
         this.address = address;
     }
 
     @Override
     public String toString() {
         return "People{" +
                 "id=" + id +
                 ", name='" + name + '\'' +
                 ", age=" + age +
                 ", address='" + address + '\'' +
                 '}';
     }
 }

用jsp去创建一个实体对象

<body>
 <%
 //    People people = new People();
 %>
 
 <jsp:useBean id="people" class="com.gu.pojo.People" scope="page">
 
 </jsp:useBean>
 <jsp:setProperty name="people" property="address" value="hunan"></jsp:setProperty>
 <jsp:setProperty name="people" property="name" value="gugu"></jsp:setProperty>
 <jsp:setProperty name="people" property="age" value="18"></jsp:setProperty>
 <jsp:setProperty name="people" property="id" value="1"></jsp:setProperty>
 
 
 <jsp:getProperty name="people" property="name"/>
 <jsp:getProperty name="people" property="id"/>
 <jsp:getProperty name="people" property="age"/>
 <jsp:getProperty name="people" property="address"/>
 </body>