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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：

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 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

   	
    	
    		
     
      com.mysql.jdbc.Driver
     		
     
      jdbc:mysql://localhost:3306/store_07
     		
     
      root
     		
     
      root
     		
     
      30000
     		
     
      30
     		
     
      10
     		
     
      30
     		
     
      100
     		
     
      10
     		
     
      200
     		
     			
      
       10
      			
      
       1
      			
      
       0
      		
     	
     	
    	
    		
     
      com.mysql.jdbc.Driver
     		
     
      jdbc:mysql://localhost:3306/store_07
     		
     
      root
     		
     
      root
         
     		
     
      5
     		
     
      20
     		
     
      10
     		
     
      40
     		
     
      0
     		
     
      5
     	
    
   

/** * 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.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" %>
    
   		
   
   		
    			
    
   
   
	    
     
		      
商品名称
		      
市场价格
		      
商场价格
		      
商品图片
	     
	     
      
暂无数据
     
		     
				      
${
   p.pname}
				      
${
   p.market_price}
				      
${
   p.shop_price}
				      
									
			     
			    
   
<%--分页显示的开始 --%>    	
   
        		共${
   page.totalPageNum}页/第${
   page.currentPageNum}页    		    		
    首页    		    		
        			
     上一页    		
        		    		    		<%-- 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    		--%>     		
        		   
     
          		   		${
   pagenum}    		   
         		   
         		   		
      ${
   pagenum}    		   
         		
        		    		
        			
     下一页    		
        		    		    		
    末页    		    		
        		
        		    		
        	
   
    	<%--分页显示的结束--%>

product_list2.jsp

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