Java的DAO设计模式

Posted 2020-10-14 xhanglog

用java的DAO模式实现对一个学生实体的增加，查询操作。

1.建立一个学生实体类 Student.java

 1 public class Student {
 2     private String sid;
 3     private String sname;
 4     private int age;
 5     private int banji;
 6     private int score;
 7 
 8     public Student(String sid, String sname, int age, int banji, int score) {
 9         this.sid = sid;
10         this.sname = sname;
11         this.age = age;
12         this.banji = banji;
13         this.score = score;
14     }
15 
16     public String getSid() {
17         return sid;
18     }
19 
20     public void setSid(String sid) {
21         this.sid = sid;
22     }
23 
24     public String getSname() {
25         return sname;
26     }
27 
28     public void setSname(String sname) {
29         this.sname = sname;
30     }
31 
32     public int getAge() {
33         return age;
34     }
35 
36     public void setAge(int age) {
37         this.age = age;
38     }
39 
40     public int getBanji() {
41         return banji;
42     }
43 
44     public void setBanji(int banji) {
45         this.banji = banji;
46     }
47 
48     public int getScore() {
49         return score;
50     }
51 
52     public void setScore(int score) {
53         this.score = score;
54     }
55 
56     @Override
57     public String toString() {
58         return "student [sid=" + sid + ", sname=" + sname + ", age=" + age + ", banji=" + banji + ", score=" + score
59                 + "]";
60     }
61 
62 }

2.数据库连接工具类  ConnectionUtil.java

 1 import java.sql.Connection;
 2 import java.sql.DriverManager;
 3 import java.sql.ResultSet;
 4 import java.sql.SQLException;
 5 import java.sql.Statement;
 6 
 7 public class ConnectionUtil {
 8     ConnectionUtil(){}
 9     private static Connection con ;
10     
11     static{
12         try{
13             Class.forName("com.mysql.jdbc.Driver");
14             String url = "jdbc:mysql://localhost:3306/shiyan";
15             String username="root";
16             String password="1234";
17             con = DriverManager.getConnection(url, username, password);
18         }catch(Exception ex){
19             throw new RuntimeException(ex+"数据库连接失败！");
20         }
21     }
22     
23     public static Connection getConnection(){
24         return con;
25     }
26     
27     /*关闭数据库连接操作*/
28     public static void close(Connection con,Statement stat , ResultSet rs){
29          if(rs!=null){
30              try{
31                  rs.close();
32              }catch(SQLException ex){}
33          }
34          
35          if(stat!=null){
36              try{
37                  stat.close();
38              }catch(SQLException ex){}
39          }
40          
41          if(con!=null){
42              try{
43                  con.close();
44              }catch(SQLException ex){}
45          }
46          
47     }
48 }

3.DAO接口 UpdateDao.java

 1 import java.util.List;
 2 
 3 public interface UpdateDao {
 4 
 5     /*查询所有的学生，返回一个List集合中*/
 6     public List<Student> findAllStudent();
 7 
 8     /*增加学生*/
 9     public void addStudent(Student stu);
10 
11 }

4.DAO接口实现类  UpdateDaoImpl.java

 1 import java.sql.Connection;
 2 import java.sql.PreparedStatement;
 3 import java.sql.ResultSet;
 4 import java.sql.SQLException;
 5 import java.util.ArrayList;
 6 import java.util.List;
 7 
 8 public class UpdateDaoImpl implements UpdateDao {
 9 
10     @Override
11     public List<Student> findAllStudent() {
12 
13         List<Student> list = new ArrayList<Student>();
14 
15         Connection conn = ConnectionUtil.getConnection();
16         String sql = "select * from student";
17         PreparedStatement pst;
18         try {
19             pst = conn.prepareStatement(sql);
20             ResultSet rs = pst.executeQuery();
21 
22             while (rs.next()) {
23                 Student s = new Student(rs.getString("sid"), rs.getString("sname"), rs.getInt("age"),
24                         rs.getInt("banji"), rs.getInt("score"));
25                 list.add(s);
26             }
27         } catch (SQLException e) {
28             e.printStackTrace();
29         }
30         return list;
31     }
32 
33     @Override
34     public void addStudent(Student stu) {
35         Connection conn = ConnectionUtil.getConnection();
36         try {
37             String sql = "insert into student values(?,?,?,?,?)";
38             PreparedStatement pst = conn.prepareStatement(sql);
39             pst.setString(1, stu.getSid());
40             pst.setString(2, stu.getSname());
41             pst.setInt(3, stu.getAge());
42             pst.setInt(4, stu.getBanji());
43             pst.setInt(5, stu.getScore());
44 
45             pst.executeUpdate();
46 
47         } catch (Exception e) {
48             e.printStackTrace();
49         }
50 
51     }
52 
53 }

5.建立一个Junit类进行测试 TestDao.java

 1 import java.util.List;
 2 
 3 import org.junit.Test;
 4 
 5 import test3001.Student;
 6 import test3001.UpdateDao;
 7 import test3001.UpdateDaoImpl;
 8 
 9 public class testDao {
10 
11     @Test
12     /*测试增加学生*/
13     public void testaddStudent() {
14         UpdateDao dao = new UpdateDaoImpl();
15         Student stu=new Student("8","蓝猫",20,2,98);
16         dao.addStudent(stu);
17     }
18     
19     @Test
20     /*测试查询所有学生信息*/
21     public void testfindAllStudent() {
22         UpdateDao dao = new UpdateDaoImpl();
23         List<Student> list = null;
24         list = dao.findAllStudent();
25         for (Student stu : list) {
26             System.out.println(stu);
27         }
28     }
29 }

-----------泛型DAO是什么鬼 -_-      ---------------------------