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

 1 package com.g.pojo;
 2 
 3 public class Product {
 4     private String product_id;
 5     private String product_name;
 6     private double price;
 7     private String info;
 8     public String getProduct_id() {
 9         return product_id;
10     }
11     public void setProduct_id(String product_id) {
12         this.product_id = product_id;
13     }
14     public String getProduct_name() {
15         return product_name;
16     }
17     public void setProduct_name(String product_name) {
18         this.product_name = product_name;
19     }
20     public double getPrice() {
21         return price;
22     }
23     public void setPrice(double price) {
24         this.price = price;
25     }
26     public String getInfo() {
27         return info;
28     }
29     public void setInfo(String info) {
30         this.info = info;
31     }
32     
33     
34     
35 }

ProductDao.java代码

 1 package com.g.dao;
 2 
 3 import java.util.List;
 4 
 5 import com.g.pojo.Product;
 6 
 7 public interface ProductDao {
 8     /**
 9      * 数据库 新增数据
10      * @param product 要增加的数据对象
11      * @return是否增加成功的标志
12      * @throws Exception 如果有异常,将直接抛出
13      */
14     public boolean addProduct(Product product) throws Exception;
15     
16     /**
17      * 查询全部的Product
18      * @param product_name 产品名称
19      * @return返回全部的查询结果,每一个product对象表示表的一行记录
20      * @throws Exception 如果有异常,将直接抛出
21      */
22     public List<Product> findAll(String product_name)throws Exception;
23     
24     /**
25      * 根据产品编号查询产品
26      * @param product_id 产品编号
27      * @return 产品对象
28      * @throws Exception 如果有异常,将直接抛出
29      */
30     public Product findByProductId(String product_id)throws Exception;
31     
32 }

ProductService.java代码

 1 package com.g.service;
 2 
 3 import java.util.List;
 4 
 5 import com.g.dao.ProductDao;
 6 import com.g.dao.ProductDaoImpl;
 7 import com.g.db.DBConnection;
 8 import com.g.pojo.Product;
 9 
10 /**
11  * 操作数据库
12  * @author 思思博士
13  *
14  */
15 public class ProductService implements ProductDao{
16     
17     private DBConnection dbconn=null;
18     private ProductDao dao=null;
19     //在构造方法中实例化数据库连接,同时实例化dao对象
20     public ProductService() throws Exception{
21         this.dbconn=new DBConnection();
22         //实例化ProductDao的实现类
23         this.dao=new ProductDaoImpl(this.dbconn.getConnection());                
24     }    
25     public boolean addProduct(Product product) throws Exception {
26         boolean flag=false;
27         try{
28             if(this.dao.findByProductId(product.getProduct_id())==null){
29                 //如果要插入的产品编号不存在
30                 flag=this.dao.addProduct(product);//新增一条产品信息
31             }
32         }
33         catch (Exception e) {
34             throw e;
35         }finally{
36             this.dbconn.close();
37         }
38         
39         return flag;
40     }
41 
42     public List<Product> findAll(String keyWord) throws Exception {
43         List<Product> all=null; //定义产品返回的集合
44         try {
45             all=this.dao.findAll(keyWord);
46         } catch (Exception e) {
47             throw e;
48         }finally{
49             this.dbconn.close();
50         }
51         return all;
52     }
53 
54     public Product findByProductId(String product_id) throws Exception {
55         Product product=null;
56         try {
57             product=this.dao.findByProductId(product_id);
58         } catch (Exception e) {
59             throw e;
60         }finally{
61             this.dbconn.close();
62         }
63         return product;
64     }
65 }

 

DBConnection.java代码

 1 package com.g.db;
 2 
 3 import java.sql.Connection;
 4 import java.sql.DriverManager;
 5 
 6 public class DBConnection {
 7     private static final String Driver="com.mysql.jdbc.Driver";
 8     private static final String Url="jdbc:mysql://127.0.0.1:3306/testweb";
 9     private static final String User="root";
10     private static final String Password="gys";
11     private Connection conn=null;
12     
13     //进行数据库连接
14     public DBConnection() throws Exception{
15         try{
16             //用反射加载数据库驱动
17             Class.forName(Driver);
18             this.conn=DriverManager.getConnection(Url,User,Password);
19         }
20         catch (Exception e) {
21             throw e;
22         }
23     }
24     //取得数据库的连接
25     public Connection getConnection(){
26         return this.conn;        
27     }
28     //关闭数据库
29     public void close() throws Exception{
30         if(this.conn!=null){
31             try {
32                 this.conn.close();
33                 
34             } catch (Exception e) {
35                 throw e;
36             }
37         }
38     }
39     
40 }

 

 

ProductDaoImpI.java代码

 1 package com.g.dao;
 2 
 3 import java.sql.Connection;
 4 import java.sql.PreparedStatement;
 5 import java.sql.ResultSet;
 6 import java.util.ArrayList;
 7 import java.util.List;
 8 
 9 import com.g.pojo.Product;
10 
11 /**
12  * 实现DAO接口的类.但是不负责数据库的打开和关闭
13  * @author 思思博士
14  *
15  */
16 public class ProductDaoImpl implements ProductDao{
17     private Connection conn=null;
18     private PreparedStatement pstmt=null;
19     //通过构造方法取得数据库连接
20     public ProductDaoImpl(Connection conn){
21         this.conn=conn;
22     }
23     public boolean addProduct(Product product) throws Exception {
24         boolean flag=false;
25         String sql="insert into product(product_id,product_name,price,info) values(?,?,?,?)";
26         this.pstmt=this.conn.prepareStatement(sql);
27         this.pstmt.setString(1,product.getProduct_id());
28         this.pstmt.setString(2,product.getProduct_name());
29         this.pstmt.setDouble(3,product.getPrice());
30         this.pstmt.setString(4,product.getInfo());
31         
32         if(this.pstmt.executeUpdate()>0){
33             flag=true;
34         }
35         this.pstmt.close();
36         return flag;
37     }
38     
39     public List<Product> findAll(String product_name) throws Exception {        
40         List<Product> list=new ArrayList<Product>();
41         String sql="select product_id,product_name,price,info from product";
42         if(product_name!=null&&!"".equals(product_name)){
43             sql="select product_id,product_name,price,info from product where product_name like ?";
44             this.pstmt=this.conn.prepareStatement(sql);
45             this.pstmt.setString(1,"%"+product_name+"%");
46         }
47         else {
48             this.pstmt=this.conn.prepareStatement(sql);
49         }
50         ResultSet rs=this.pstmt.executeQuery();
51         Product product=null;
52         while(rs.next()){
53             product=new Product();
54             product.setProduct_id(rs.getString(1));
55             product.setProduct_name(rs.getString(2));
56             product.setPrice(rs.getDouble(3));
57             product.setInfo(rs.getString(4));
58             list.add(product);
59         }
60         this.pstmt.close();
61         return list;
62     }
63     
64     public Product findByProductId(String product_id) throws Exception {
65         Product product=null;
66         String sql="select product_id,product_name,price,info from product where product_id=?";
67         this.pstmt=this.conn.prepareStatement(sql);
68         this.pstmt.setString(1,product_id);
69         ResultSet rs=this.pstmt.executeQuery();
70         if(rs.next()){
71             product=new Product();
72             product.setProduct_id(rs.getString(1));
73             product.setProduct_name(rs.getString(2));
74             product.setPrice(rs.getDouble(3));
75             product.setInfo(rs.getString(4));
76         }
77         this.pstmt.close();
78         return product;
79     }
80     
81     
82 }

DAOFactory.java代码

 1 package com.g.factory;
 2 
 3 import com.g.dao.ProductDao;
 4 import com.g.service.ProductService;
 5 
 6 public class DAOFactory {
 7     public static ProductDao getIEmpDAOInstance() throws Exception{
 8         //取得业务操作类
 9         return new ProductService();
10     }
11 }

TestInsertProduct.java代码

 1 package com.g.test;
 2 
 3 import com.g.factory.DAOFactory;
 4 import com.g.pojo.Product;
 5 
 6 public class TestInsertProduct {
 7     public static void main(String[] args) {
 8         Product product=null;
 9         try {
10             for(int i=0;i<5;i++){
11                 product=new Product();
12                 product.setProduct_id("350115001010"+i);
13                 product.setProduct_name("水杯"+i);
14                 product.setPrice(100+i);
15                 product.setInfo("这是一个精美的杯子"+i);
16                 DAOFactory.getIEmpDAOInstance().addProduct(product);
17             }
18         } catch (Exception e) {
19             e.printStackTrace();
20         }
21     }
22 }

add.jsp代码

 1 <%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%>
 2 <%
 3 String path = request.getContextPath();
 4 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
 5 %>
 6 
 7 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
 8 <html>
 9   <head>
10     <base href="<%=basePath%>">
11     
12     <title>添加产品</title>
13   </head>
14   
15   <body>
16     <form action="insert.jsp" method="post">
17         产品编号:<input name="product_id" /><br/>
18         产品名称:<input name="product_name" /><br />
19         产品价格:<input name="price" /><br/>
20         产品信息:<textarea rows="5" cols="15" name="info"></textarea><br/>
21         <input type="submit" value="添加" />&nbsp;&nbsp;
22         <input type="reset" value="重置" />
23     </form>
24   </body>
25 </html>

insert.jsp代码

 1 <%@page import="com.g.factory.DAOFactory"%>
 2 <%@page import="com.g.pojo.Product"%>
 3 <%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%>
 4 <%
 5 String path = request.getContextPath();
 6 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
 7 %>
 8 
 9 <%
10  request.setCharacterEncoding("utf-8");
11  %>
12 
13 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
14 <html>
15   <head>
16     <base href="<%=basePath%>">    
17     <title>执行添加产品</title>
18   </head>
19   
20   <body>
21     <%
22         Product product=new Product();
23         product.setProduct_id(request.getParameter("product_id"));
24         product.setProduct_name(request.getParameter("product_name"));
25         product.setPrice(Double.parseDouble(request.getParameter("price")));
26         product.setInfo(request.getParameter("info"));
27         boolean flag=DAOFactory.getIEmpDAOInstance().addProduct(product);//执行添加操作
28         if(flag){
29         %>
30         <h4>添加产品信息成功</h4>
31         <%}else{%>
32         <h4>添加产品信息失败.</h4>
33         <%} %>
34   </body>
35 </html>

list.jsp代码

 1 <%@page import="com.g.factory.DAOFactory"%>
 2 <%@page import="com.g.pojo.Product"%>
 3 <%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%>
 4 <%
 5 String path = request.getContextPath();
 6 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
 7 %>
 8 <%request.setCharacterEncoding("utf-8"); %>
 9 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
10 <html>
11   <head>
12     <base href="<%=basePath%>">    
13     <title>查询产品列表</title>
14   </head>
15   
16   <body>
17    <%
18        String product_name=request.getParameter("product_name");
19        if(product_name==null)
20            product_name="";
21        List<Product> list=DAOFactory.getIEmpDAOInstance().findAll(product_name);
22     %>
23     <form action="list.jsp" method="post">
24         请输入产品名称:<input name="product_name" value="<%=product_name %>"/>
25         <input type="submit" value="提交" />
26     </form>
27     <table>
28         <tr>
29             <td>产品编号</td>
30             <td>产品名称</td>
31             <td>产品价格</td>
32             <td>产品信息</td>
33         </tr>
34         <%
35             for(int i=0;i<list.size();i++){
36                 Product p=list.get(i);//取出每一个产品
37             %>
38             <tr>
39                  <td><%=p.getProduct_id() %></td>
40                  <td><%=p.getProduct_name() %></td>
41                  <td><%=p.getPrice() %></td>
42                  <td><%=p.getInfo() %></td>
43              </tr>
44             <%}%>
45          
46          
47     </table>
48   </body>
49 </html>

 

来源：https://www.cnblogs.com/guoyansi19900907/p/4405013.html