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Java Web 网络商城案例演示十一（商品分页）

程序员文章站 2024-01-15 23:08:58
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Java Web 网络商城案例演示十一（商品分页）
基础的分页操作
web阶段项目中：CRUD,ajax,分页，下载，上传
新建一个动态的web工程

分析SQL语句的实现

– 约定每页能够显示5条数据

SELECT * FROM product LIMIT 0,5;
SELECT * FROM product LIMIT 5,5;
SELECT * FROM product LIMIT 10,5;
SELECT * FROM product LIMIT 15,5;

第几页数（当前页） 起始值 每一页数据的大小
1 0 5
2 5 5
3 10 5
4 15 5

结论：

1、（当前页减去1）乘以（每页的数量）=起始值
2、结论要想实现分页，向服务端发起请求的时候，必须传递当前页

原理分析：

步骤实现：
Java Web 网络商城案例演示十一（商品分页）
1、new DynamicWebProject (TestPageination)
2、导入jar包，工具类，配置文件（修改参数）创建相关的程序servlet,service ,dao ,product
Java Web 网络商城案例演示十一（商品分页）
在utils下面创建Product 类

public class Product {
		
	private String pid;//商品编号
	private String pname;//商品的名称
	private double market_price;//商品市场价格
	private double shop_price;//商品的商场价格
	private String pimage;//商品的图片路径
	private Date pdate;//商品的上架的日期
	private String is_hot;//商品是否热门
	private String pdesc;//商品描述
	private int pflag;//商品的是否在货架上  0 在货架上 1 下架
	private String cid;//商品所在分类的id
	public String getPid() {
		return pid;
	}
	public void setPid(String pid) {
		this.pid = pid;
	}
	public String getPname() {
		return pname;
	}
	public void setPname(String pname) {
		this.pname = pname;
	}
	public double getMarket_price() {
		return market_price;
	}
	public void setMarket_price(double market_price) {
		this.market_price = market_price;
	}
	public double getShop_price() {
		return shop_price;
	}
	public void setShop_price(double shop_price) {
		this.shop_price = shop_price;
	}
	public String getPimage() {
		return pimage;
	}
	public void setPimage(String pimage) {
		this.pimage = pimage;
	}
	public Date getPdate() {
		return pdate;
	}
	public void setPdate(Date pdate) {
		this.pdate = pdate;
	}
	public String getIs_hot() {
		return is_hot;
	}
	public void setIs_hot(String is_hot) {
		this.is_hot = is_hot;
	}
	public String getPdesc() {
		return pdesc;
	}
	public void setPdesc(String pdesc) {
		this.pdesc = pdesc;
	}
	public int getPflag() {
		return pflag;
	}
	public void setPflag(int pflag) {
		this.pflag = pflag;
	}
	public String getCid() {
		return cid;
	}
	public void setCid(String cid) {
		this.cid = cid;
	}
	public Product() {
		// TODO Auto-generated constructor stub
	}
	public Product(String pid, String pname, double market_price, double shop_price, String pimage, Date pdate,
			String is_hot, String pdesc, int pflag, String cid) {
		super();
		this.pid = pid;
		this.pname = pname;
		this.market_price = market_price;
		this.shop_price = shop_price;
		this.pimage = pimage;
		this.pdate = pdate;
		this.is_hot = is_hot;
		this.pdesc = pdesc;
		this.pflag = pflag;
		this.cid = cid;
	}
	@Override
	public String toString() {
		return "Product [pid=" + pid + ", pname=" + pname + ", market_price=" + market_price + ", shop_price="
				+ shop_price + ", pimage=" + pimage + ", pdate=" + pdate + ", is_hot=" + is_hot + ", pdesc=" + pdesc
				+ ", pflag=" + pflag + ", cid=" + cid + "]";
	}
}

c3p0链接数据库

<c3p0-config>
	<!-- 默认配置，如果没有指定则使用这个配置 -->
	<default-config>
		<property name="driverClass">com.mysql.jdbc.Driver</property>
		<property name="jdbcUrl">jdbc:mysql://localhost:3306/store_07</property>
		<property name="user">root</property>
		<property name="password">root</property>
		<property name="checkoutTimeout">30000</property>
		<property name="idleConnectionTestPeriod">30</property>
		<property name="initialPoolSize">10</property>
		<property name="maxIdleTime">30</property>
		<property name="maxPoolSize">100</property>
		<property name="minPoolSize">10</property>
		<property name="maxStatements">200</property>
		<user-overrides user="test-user">
			<property name="maxPoolSize">10</property>
			<property name="minPoolSize">1</property>
			<property name="maxStatements">0</property>
		</user-overrides>
	</default-config> 
	<!-- 命名的配置 -->
	<named-config name="itzheng">
		<property name="driverClass">com.mysql.jdbc.Driver</property>
		<property name="jdbcUrl">jdbc:mysql://localhost:3306/store_07</property>
		<property name="user">root</property>
		<property name="password">root</property>
    <!-- 如果池中数据连接不够时一次增长多少个 -->
		<property name="acquireIncrement">5</property>
		<property name="initialPoolSize">20</property>
		<property name="minPoolSize">10</property>
		<property name="maxPoolSize">40</property>
		<property name="maxStatements">0</property>
		<property name="maxStatementsPerConnection">5</property>
	</named-config>
</c3p0-config>

/**
 * Servlet implementation class ProductServlet
 */
public class ProductServlet extends HttpServlet {
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public ProductServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	private static final long serialVersionUID = 1L;
    
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		this.doPost(request, response);
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//接收当前页
		String num=request.getParameter("num");
		int curNum=Integer.parseInt(num);
		System.out.println(curNum);
		
		ProductService ProductService=new ProductService();
		//调用业务层查询当前页功能,返回PageModel对象(1_当前页数据2_分页参数)
		PageModel pm=null;
		try {
			pm = ProductService.findProducts(curNum);
		} catch (Exception e) {
			e.printStackTrace();
		}
		//将PageModel对象放入request
		request.setAttribute("page", pm);
		//request.getRequestDispatcher("/product_list.jsp").forward(request, response);
		request.getRequestDispatcher("/product_list2.jsp").forward(request, response);
	}

}


public class ProductService {
	public PageModel findProducts(int curNum) throws SQLException{
		//1_创建PageModel对象 目的:计算分页参数
		ProductDao ProductDao=new ProductDao();
		int totalRecords=ProductDao.findToralRecords();
		PageModel pm=new PageModel(curNum,5,totalRecords);//传入要点击的页数，和每页的页数，和对应总信息的条数
		//2_关联数据  select * from product limit  ? , ?
		List list=ProductDao.findProducts(pm.getStartIndex(),pm.getPageSize());
		pm.setList(list);
		//3_关联url
		pm.setUrl("ProductServlet");
		return pm;
	}
}

public class ProductDao {
	//统计表中有多少条数据
	public int findToralRecords() throws SQLException {
		QueryRunner qr = new QueryRunner(JDBCUtils.getDataSource());
		Long  num=(Long)qr.query("select count(*) from product",new ScalarHandler());
		return num.intValue();
	}
	public List findProducts(int startIndex, int pageSize) throws SQLException {
		String sql="select * from product limit ? ,? ";
		QueryRunner qr = new QueryRunner(JDBCUtils.getDataSource());
		return qr.query(sql, new BeanListHandler<Product>(Product.class),startIndex,pageSize);
	}
}

product_list.jsp

<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!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> 
<table border="1" width="100%">
	<tr>
		<td>商品名称</td>
		<td>市场价格</td>
		<td>商场价格</td>
		<td>商品图片</td>
	</tr>
	<c:if test="${empty page.list }">
		<tr><td colspan="4">暂无数据</td></tr>
	</c:if>
	<c:if test="${not empty page.list }">
		<c:forEach items="${page.list}" var="p">
			<tr>
				<td>${p.pname}</td>
				<td>${p.market_price}</td>
				<td>${p.shop_price}</td>
				<td>
					<img src="${pageContext.request.contextPath}/${p.pimage}" width="50px"/>
				</td>
			</tr>
		</c:forEach>
	</c:if>
</table>

<%--分页显示的开始 --%>
    	<div style="text-align:center">
    		共${page.totalPageNum}页/第${page.currentPageNum}页
    		
    		<a href="${pageContext.request.contextPath}/ProductServlet?num=1">首页</a>
    		
    		<c:if test="${page.currentPageNum != 1}">
    			<a href="${pageContext.request.contextPath}/ProductServlet?num=${page.prePageNum}">上一页</a>
    		</c:if>
    		
    		
    		<%-- 获取开始结束页码
    			 ${page} *.getAttribute("page");  获取到pageModel对象
    			 ${page.startPage} 调用PageModel对象getStartPage()方法
    		--%> 
    		<c:forEach begin="${page.startPage}" end="${page.endPage}" var="pagenum">
    		   <c:if test="${page.currentPageNum==pagenum}">
    		   		${pagenum}
    		   </c:if>
    		   <c:if test="${page.currentPageNum!=pagenum}">
    		   		<a href="${pageContext.request.contextPath}/ProductServlet?num=${pagenum}">${pagenum}</a>
    		   </c:if>
    		</c:forEach>
    		
    		<c:if test="${page.currentPageNum != page.totalPageNum}">
    			<a href="${pageContext.request.contextPath}/ProductServlet?num=${page.nextPageNum}">下一页</a>
    		</c:if>
    		
    		
    		<a href="${pageContext.request.contextPath}/ProductServlet?num=${page.totalPageNum}">末页</a>
    		
    		<input type="text" id="pagenum" name="pagenum" size="1"/>
    		<input type="button" value="前往" onclick="jump()" />
    		
    		<script type="text/javascript">
    			function jump(){
    				
    				//通过EL获取到总共页数,赋值给JS中变量
    				var totalpage = ${page.totalPageNum};
    				//获取到用户输入的内容
    				var pagenum = document.getElementById("pagenum").value;
    				//判断输入的是一个数字
    				var reg =/^[1-9][0-9]*$/;
    				if(!reg.test(pagenum)){
    					//不是一个有效数字
    					alert("请输入符合规定的数字");
    					return ;
    				}
    				//paseInt(pageNum):将用户输入的内容转换为int类型数字
    				//判断输入的数字不能大于总页数
    				if(parseInt(pagenum)>parseInt(totalpage)){
    					//超过了总页数
    					alert("不能大于总页数");
    					return;
    				}
    				//转向分页显示的Servlet
    				window.location.href="${pageContext.request.contextPath}/ProductServlet?num="+pagenum;
    			}
    		</script>
    	</div>
    	<%--分页显示的结束--%>


</body>
</html>

product_list2.jsp

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