javaBean的使用方法;

在jsp页面中使用javaBean:三个标签;

<jsp:useBean>标签

<jsp:setProperty>标签

<jsp:getProperty>标签

首先建立一个customer类:

package com.lanqiao.javatest;

public class Customer {
    private Integer id;
    private String name;
    private int age;
    public Customer() {
        super();
        // TODO Auto-generated constructor stub
    }
    public Customer(Integer id, String name, int age) {
        super();
        this.id = id;
        this.name = name;
        this.age = age;
    }
    public Integer getId() {
        return id;
    }
    public void setId(Integer 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;
    }
    @Override
    public String toString() {
        return "Customer [id=" + id + ", name=" + name + ", age=" + age + "]";
    }
    
    
}

 

建立一个jsp页面:直接调用customer的属性和方法,并且可以给属性赋值;

<%@page import="com.atguigu.javaweb.Customer"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
    
    <jsp:useBean id="customer" class="com.lanqiao.javatest.Customer" 
        scope="request"></jsp:useBean>
    
    <jsp:useBean id="customer2" beanName="com.lanqiao.javatest.Customer"
        type="java.lang.Object" scope="request"></jsp:useBean>
        
    <%-- 
        Object customer2 = request.getAttribute("customer2");
        if(customer2){
            customer2 = Class.forName("com.lanqiao.javatest.Customer").newInstance();
            request.setAttribute("customer2", customer2);
        }
    --%>    
        
    <!-- 若 property 的值为 *, 省略 value 属性值, 则将自动为所有属性赋值为对应的请求参数的值.  -->    
    <jsp:setProperty property="*" name="customer"/>
    
    <%-- 
    <jsp:setProperty property="name" value="ATGUIGU2" name="customer"/>
    --%>
    
    age: <jsp:getProperty property="age" name="customer"/> 
    <br>
    name: <jsp:getProperty property="name" name="customer"/>
    <br>
    id: <jsp:getProperty property="id" name="customer"/>
    
    <%-- 
    <%= customer.getAge() %>
    --%>
        
    <%-- 
        customer.setAge(10);
    --%>    
    
    <%-- 
        //1. 从 scope(session) 中获取 id(customer) 属性值, 赋给 class(com.lanqiao.javatest.Customer) 
        //类型的 id(customer) 变量
        Customer customer = (Customer)session.getAttribute("customer");
        
        //2. 若属性值为 null, 则利用反射创建一个新的对象, 把该对象赋给 id(customer), 并以 id(customer) 
        //为属性名让如到 scope(session) 中.
        if(customer == null){
            customer = (Customer)Class.forName("com.lanqiao.javatest.Customer").newInstance();
            session.setAttribute("customer", customer);
        }
    --%>
    
</body>
</html>

 

posted @ 2016-09-01 17:11  G-&-D  阅读(1344)  评论(0编辑  收藏  举报