简单的小Demo
实体类
JavaBean特定的写法
- 必须要有一个无参构造
- 属性必须私有化
- 必须有对应的get/set方法
一般用来和数据库的字段做映射 ORM；
ORM：对象关系映射
- 表–>类
- 字段–>属性
- 行记录–>对象
People类
| index | name | age | address |
| 1 | 老大 | 3 | 天 |
| 2 | 老二 | 2 | 天 |
| 3 | 老三 | 1 | 天 |
package com.hxl.pojo; //实体类 我们一般都是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 People() { } 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 + '\'' + '}'; } }
<%@ page import="com.hxl.pojo.People" %> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>Title</title> </head> <body> <% //下面那句话等价于 /* People people = new People(); people.setId(); people.setName(); people.setAge(); people.setAddress(); */ %> <jsp:useBean id="people" class="com.hxl.pojo.People" scope="page"/> <%--name代表你要设的对象，property代表属性--%> <jsp:setProperty name="people" property="id" value="4"/> <jsp:setProperty name="people" property="name" value="老四"/> <jsp:setProperty name="people" property="age" value="5"/> <jsp:setProperty name="people" property="address" value="天"/> <%-- 下面就相当于<%=people.getId()%> --%> 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>
谈一下在idea中连接数据库
- 测试连接的时候如果出现
- 问题1：Server returns invalid timezone. Go to ‘Advanced’ tab and set ‘serverTimezone’ property manually.
- 解决：在cmd中输入mysql -hlocalhost -uroot -p回车输入密码。 继续输入show variables like’%time_zone’; 不要忘记分号，查看Value如果值为SYSTEM则需要设置时区。我用的是mysql8所以输入set time_zone = ‘+8:00’; 同样注意分号。如果其他版本可能需要在set后加global。设置完成后再次查看即可
- 问题2：The specified database user/password combination is rejected:
- 解决：重新修改一下密码就好。用最简单的修改方式，Navicat中进行修改
