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>