servlet实操之javabean

javaBean

实体类

javaBean有特定的写法：

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

id	name	age	address
1	shi01	10	北京
2	shi02	34	北京
3	shi03	54	北京

class people{
    private int id;
    private String name;
    private int age;
    private String address;
}
class A{
    new people(1,"shi01",3,"北京");
}

jsp与实体层交互

<%--    java方式--%>
<%
    People people = new People();
    people.setAddress("北京");
    people.setAge(13);
    people.setId(1);
    people.setName("shi");
%>
<%--    jsp方式--%>
<jsp:useBean id="people" class="com.shiy.pojo.People" scope="page">
    <jsp:setProperty name="people" property="address" value="北京"></jsp:setProperty>
    <jsp:setProperty name="people" property="id" value="1"></jsp:setProperty>
    <jsp:setProperty name="people" property="age" value="16"></jsp:setProperty>
    <jsp:setProperty name="people" property="name" value="shi"></jsp:setProperty>
    id:<jsp:getProperty name="people" property="id"/>
    name:<jsp:getProperty name="people" property="name"/>
    age:<jsp:getProperty name="people" property="age"/>
    address:<jsp:getProperty name="people" property="address"/>
<%--    java方式--%>
    address:<%=people.getAddress()%>
</jsp:useBean>