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 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 findAll(String keyWord) throws Exception {43 List 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 findAll(String product_name) throws Exception { 40 List list=new ArrayList();

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 8 9

10 \">11

12 13 14

15

16

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 14 15

16 \"> 17 18 19

20 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

添加产品信息成功

32

添加产品信息失败.

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 10 11

12 \">

13 14 15

16 17 <%

18 String product_name=request.getParameter(\"product_name\");19 if(product_name==null)20 product_name=\"\";

21 List list=DAOFactory.getIEmpDAOInstance().findAll(product_name);22 %>

23

29

35 for(int i=0;i36 Product p=list.get(i);//取出每⼀个产品37 %>38

39

47