入门JavaWeb之 JavaBean 实体类

JavaBean 有特定写法：

1.必须有一个无参构造

2.属性必须私有

3.必须有对应的 get/set 方法

一般用来和数据库的字段做映射

ORM：对象关系映射

表->类

字段->属性

行记录->对象

连接数据库

没有的话去 Settings -> Plugins 搜索 DataBase 下载

属性私有

按 alt + insert

Constructor 构造器：

Getter and Setter：

toString()：

MySQL 建表：

IDEA 显示表：

实体类和数据库中的表结构一一对应

代码如下：

package com.demo.entity;//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() {}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;}@Overridepublic String toString() {return "People{" +"id=" + id +", name='" + name + '\'' +", age=" + age +", address='" + address + '\'' +'}';}}

新建一个 javabean.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<body><%//People people = new People();//people.setId();//people.setName();//people.setAge();//people.setAddress();
%><jsp:useBean id="people" class="com.demo.entity.People" scope="page"/> <%-- page表示当前作用域 --%><jsp:setProperty name="people" property="id" value="1"/>
<jsp:setProperty name="people" property="name" value="hh"/>
<jsp:setProperty name="people" property="age" value="12"/>
<jsp:setProperty name="people" property="address" value="天河"/>id：<jsp:getProperty name="people" property="id"/>
姓名：<jsp:getProperty name="people" property="name"/>
年龄：<jsp:getProperty name="people" property="age"/>
地址：<jsp:getProperty name="people" property="address"/></body>
</html>

执行，页面效果如下：