java中的DAO设计模式

创建数据库和表

sql语句:

DROP TABLE IF EXISTS product;
CREATE TABLE product(
       product_id varchar(20) NOT NULL,
       product_name varchar(50) DEFAULT NULL,
       price decimal(6,2) DEFAULT NULL,
       info varchar(100) DEFAULT NULL,
       PRIMARY KEY(product_id)
)ENGINE=InnoDB DEFAULT CHARSET=utf8;

文件目录如下

Product.java

 package com.g.pojo;

 public class Product {
     private String product_id;
     private String product_name;
     private double price;
     private String info;
     public String getProduct_id() {
         return product_id;
     }
     public void setProduct_id(String product_id) {
         this.product_id = product_id;
     }
     public String getProduct_name() {
         return product_name;
     }
     public void setProduct_name(String product_name) {
         this.product_name = product_name;
     }
     public double getPrice() {
         return price;
     }
     public void setPrice(double price) {
         this.price = price;
     }
     public String getInfo() {
         return info;
     }
     public void setInfo(String info) {
         this.info = info;
     }

 }

ProductDao.java代码

 package com.g.dao;

 import java.util.List;

 import com.g.pojo.Product;

 public interface ProductDao {
     /**
      * 数据库 新增数据
      * @param product 要增加的数据对象
      * @return是否增加成功的标志
      * @throws Exception 如果有异常,将直接抛出
      */
     public boolean addProduct(Product product) throws Exception;

     /**
      * 查询全部的Product
      * @param product_name 产品名称
      * @return返回全部的查询结果,每一个product对象表示表的一行记录
      * @throws Exception 如果有异常,将直接抛出
      */
     public List<Product> findAll(String product_name)throws Exception;

     /**
      * 根据产品编号查询产品
      * @param product_id 产品编号
      * @return 产品对象
      * @throws Exception 如果有异常,将直接抛出
      */
     public Product findByProductId(String product_id)throws Exception;

 }

ProductService.java代码

 package com.g.service;

 import java.util.List;

 import com.g.dao.ProductDao;
 import com.g.dao.ProductDaoImpl;
 import com.g.db.DBConnection;
 import com.g.pojo.Product;

 /**
  * 操作数据库
  * @author 思思博士
  *
  */
 public class ProductService implements ProductDao{

     private DBConnection dbconn=null;
     private ProductDao dao=null;
     //在构造方法中实例化数据库连接,同时实例化dao对象
     public ProductService() throws Exception{
         this.dbconn=new DBConnection();
         //实例化ProductDao的实现类
         this.dao=new ProductDaoImpl(this.dbconn.getConnection());
     }
     public boolean addProduct(Product product) throws Exception {
         boolean flag=false;
         try{
             if(this.dao.findByProductId(product.getProduct_id())==null){
                 //如果要插入的产品编号不存在
                 flag=this.dao.addProduct(product);//新增一条产品信息
             }
         }
         catch (Exception e) {
             throw e;
         }finally{
             this.dbconn.close();
         }

         return flag;
     }

     public List<Product> findAll(String keyWord) throws Exception {
         List<Product> all=null; //定义产品返回的集合
         try {
             all=this.dao.findAll(keyWord);
         } catch (Exception e) {
             throw e;
         }finally{
             this.dbconn.close();
         }
         return all;
     }

     public Product findByProductId(String product_id) throws Exception {
         Product product=null;
         try {
             product=this.dao.findByProductId(product_id);
         } catch (Exception e) {
             throw e;
         }finally{
             this.dbconn.close();
         }
         return product;
     }
 }

DBConnection.java代码

 package com.g.db;

 import java.sql.Connection;
 import java.sql.DriverManager;

 public class DBConnection {
     private static final String Driver="com.mysql.jdbc.Driver";
     private static final String Url="jdbc:mysql://127.0.0.1:3306/testweb";
     private static final String User="root";
     private static final String Password="gys";
     private Connection conn=null;

     //进行数据库连接
     public DBConnection() throws Exception{
         try{
             //用反射加载数据库驱动
             Class.forName(Driver);
             this.conn=DriverManager.getConnection(Url,User,Password);
         }
         catch (Exception e) {
             throw e;
         }
     }
     //取得数据库的连接
     public Connection getConnection(){
         return this.conn;
     }
     //关闭数据库
     public void close() throws Exception{
         if(this.conn!=null){
             try {
                 this.conn.close();

             } catch (Exception e) {
                 throw e;
             }
         }
     }

 }

ProductDaoImpI.java代码

 package com.g.dao;

 import java.sql.Connection;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.util.ArrayList;
 import java.util.List;

 import com.g.pojo.Product;

 /**
  * 实现DAO接口的类.但是不负责数据库的打开和关闭
  * @author 思思博士
  *
  */
 public class ProductDaoImpl implements ProductDao{
     private Connection conn=null;
     private PreparedStatement pstmt=null;
     //通过构造方法取得数据库连接
     public ProductDaoImpl(Connection conn){
         this.conn=conn;
     }
     public boolean addProduct(Product product) throws Exception {
         boolean flag=false;
         String sql="insert into product(product_id,product_name,price,info) values(?,?,?,?)";
         this.pstmt=this.conn.prepareStatement(sql);
         this.pstmt.setString(1,product.getProduct_id());
         this.pstmt.setString(2,product.getProduct_name());
         this.pstmt.setDouble(3,product.getPrice());
         this.pstmt.setString(4,product.getInfo());

         if(this.pstmt.executeUpdate()>0){
             flag=true;
         }
         this.pstmt.close();
         return flag;
     }

     public List<Product> findAll(String product_name) throws Exception {
         List<Product> list=new ArrayList<Product>();
         String sql="select product_id,product_name,price,info from product";
         if(product_name!=null&&!"".equals(product_name)){
             sql="select product_id,product_name,price,info from product where product_name like ?";
             this.pstmt=this.conn.prepareStatement(sql);
             this.pstmt.setString(1,"%"+product_name+"%");
         }
         else {
             this.pstmt=this.conn.prepareStatement(sql);
         }
         ResultSet rs=this.pstmt.executeQuery();
         Product product=null;
         while(rs.next()){
             product=new Product();
             product.setProduct_id(rs.getString(1));
             product.setProduct_name(rs.getString(2));
             product.setPrice(rs.getDouble(3));
             product.setInfo(rs.getString(4));
             list.add(product);
         }
         this.pstmt.close();
         return list;
     }

     public Product findByProductId(String product_id) throws Exception {
         Product product=null;
         String sql="select product_id,product_name,price,info from product where product_id=?";
         this.pstmt=this.conn.prepareStatement(sql);
         this.pstmt.setString(1,product_id);
         ResultSet rs=this.pstmt.executeQuery();
         if(rs.next()){
             product=new Product();
             product.setProduct_id(rs.getString(1));
             product.setProduct_name(rs.getString(2));
             product.setPrice(rs.getDouble(3));
             product.setInfo(rs.getString(4));
         }
         this.pstmt.close();
         return product;
     }

 }

DAOFactory.java代码

 package com.g.factory;

 import com.g.dao.ProductDao;
 import com.g.service.ProductService;

 public class DAOFactory {
     public static ProductDao getIEmpDAOInstance() throws Exception{
         //取得业务操作类
         return new ProductService();
     }
 }

TestInsertProduct.java代码

 package com.g.test;

 import com.g.factory.DAOFactory;
 import com.g.pojo.Product;

 public class TestInsertProduct {
     public static void main(String[] args) {
         Product product=null;
         try {
             for(int i=0;i<5;i++){
                 product=new Product();
                 product.setProduct_id("350115001010"+i);
                 product.setProduct_name("水杯"+i);
                 product.setPrice(100+i);
                 product.setInfo("这是一个精美的杯子"+i);
                 DAOFactory.getIEmpDAOInstance().addProduct(product);
             }
         } catch (Exception e) {
             e.printStackTrace();
         }
     }
 }

add.jsp代码

 <%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%>
 <%
 String path = request.getContextPath();
 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
 %>

 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
 <html>
   <head>
     <base href="<%=basePath%>">

     <title>添加产品</title>
   </head>

   <body>
     <form action="insert.jsp" method="post">
         产品编号:<input name="product_id" /><br/>
         产品名称:<input name="product_name" /><br />
         产品价格:<input name="price" /><br/>
         产品信息:<textarea rows="5" cols="15" name="info"></textarea><br/>
         <input type="submit" value="添加" />&nbsp;&nbsp;
         <input type="reset" value="重置" />
     </form>
   </body>
 </html>

insert.jsp代码

 <%@page import="com.g.factory.DAOFactory"%>
 <%@page import="com.g.pojo.Product"%>
 <%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%>
 <%
 String path = request.getContextPath();
 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
 %>

 <%
  request.setCharacterEncoding("utf-8");
  %>

 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
 <html>
   <head>
     <base href="<%=basePath%>">
     <title>执行添加产品</title>
   </head>

   <body>
     <%
         Product product=new Product();
         product.setProduct_id(request.getParameter("product_id"));
         product.setProduct_name(request.getParameter("product_name"));
         product.setPrice(Double.parseDouble(request.getParameter("price")));
         product.setInfo(request.getParameter("info"));
         boolean flag=DAOFactory.getIEmpDAOInstance().addProduct(product);//执行添加操作
         if(flag){
         %>
         <h4>添加产品信息成功</h4>
         <%}else{%>
         <h4>添加产品信息失败.</h4>
         <%} %>
   </body>
 </html>

list.jsp代码

 <%@page import="com.g.factory.DAOFactory"%>
 <%@page import="com.g.pojo.Product"%>
 <%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%>
 <%
 String path = request.getContextPath();
 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
 %>
 <%request.setCharacterEncoding("utf-8"); %>
 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
 <html>
   <head>
     <base href="<%=basePath%>">
     <title>查询产品列表</title>
   </head>

   <body>
    <%
        String product_name=request.getParameter("product_name");
        if(product_name==null)
            product_name="";
        List<Product> list=DAOFactory.getIEmpDAOInstance().findAll(product_name);
     %>
     <form action="list.jsp" method="post">
         请输入产品名称:<input name="product_name" value="<%=product_name %>"/>
         <input type="submit" value="提交" />
     </form>
     <table>
         <tr>
             <td>产品编号</td>
             <td>产品名称</td>
             <td>产品价格</td>
             <td>产品信息</td>
         </tr>
         <%
             for(int i=0;i<list.size();i++){
                 Product p=list.get(i);//取出每一个产品
             %>
             <tr>
                  <td><%=p.getProduct_id() %></td>
                  <td><%=p.getProduct_name() %></td>
                  <td><%=p.getPrice() %></td>
                  <td><%=p.getInfo() %></td>
              </tr>
             <%}%>

     </table>
   </body>
 </html>