Java的DAO设计模式

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

public class Student {
    private String sid;
    private String sname;
    private int age;
    private int banji;
    private int score;

    public Student(String sid, String sname, int age, int banji, int score) {
        this.sid = sid;
        this.sname = sname;
        this.age = age;
        this.banji = banji;
        this.score = score;
    }

    public String getSid() {
        return sid;
    }

    public void setSid(String sid) {
        this.sid = sid;
    }

    public String getSname() {
        return sname;
    }

    public void setSname(String sname) {
        this.sname = sname;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public int getBanji() {
        return banji;
    }

    public void setBanji(int banji) {
        this.banji = banji;
    }

    public int getScore() {
        return score;
    }

    public void setScore(int score) {
        this.score = score;
    }

    @Override
    public String toString() {
        return "student [sid=" + sid + ", sname=" + sname + ", age=" + age + ", banji=" + banji + ", score=" + score
                + "]";
    }

}

2.数据库连接工具类  ConnectionUtil.java

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class ConnectionUtil {
    ConnectionUtil(){}
    private static Connection con ;
    
    static{
        try{
            Class.forName("com.mysql.jdbc.Driver");
            String url = "jdbc:mysql://localhost:3306/shiyan";
            String username="root";
            String password="1234";
            con = DriverManager.getConnection(url, username, password);
        }catch(Exception ex){
            throw new RuntimeException(ex+"数据库连接失败！");
        }
    }
    
    public static Connection getConnection(){
        return con;
    }
    
    /*关闭数据库连接操作*/
    public static void close(Connection con,Statement stat , ResultSet rs){
         if(rs!=null){
             try{
                 rs.close();
             }catch(SQLException ex){}
         }
         
         if(stat!=null){
             try{
                 stat.close();
             }catch(SQLException ex){}
         }
         
         if(con!=null){
             try{
                 con.close();
             }catch(SQLException ex){}
         }
         
    }
}

3.DAO接口 UpdateDao.java

import java.util.List;

public interface UpdateDao {

    /*查询所有的学生，返回一个List集合中*/
    public List<Student> findAllStudent();

    /*增加学生*/
    public void addStudent(Student stu);

}

4.DAO接口实现类  UpdateDaoImpl.java

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

public class UpdateDaoImpl implements UpdateDao {

    @Override
    public List<Student> findAllStudent() {

        List<Student> list = new ArrayList<Student>();

        Connection conn = ConnectionUtil.getConnection();
        String sql = "select * from student";
        PreparedStatement pst;
        try {
            pst = conn.prepareStatement(sql);
            ResultSet rs = pst.executeQuery();

            while (rs.next()) {
                Student s = new Student(rs.getString("sid"), rs.getString("sname"), rs.getInt("age"),
                        rs.getInt("banji"), rs.getInt("score"));
                list.add(s);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return list;
    }

    @Override
    public void addStudent(Student stu) {
        Connection conn = ConnectionUtil.getConnection();
        try {
            String sql = "insert into student values(?,?,?,?,?)";
            PreparedStatement pst = conn.prepareStatement(sql);
            pst.setString(1, stu.getSid());
            pst.setString(2, stu.getSname());
            pst.setInt(3, stu.getAge());
            pst.setInt(4, stu.getBanji());
            pst.setInt(5, stu.getScore());

            pst.executeUpdate();

        } catch (Exception e) {
            e.printStackTrace();
        }

    }

}

5.建立一个Junit类进行测试 TestDao.java

import java.util.List;

import org.junit.Test;

import test3001.Student;
import test3001.UpdateDao;
import test3001.UpdateDaoImpl;

public class testDao {

    @Test
    /*测试增加学生*/
    public void testaddStudent() {
        UpdateDao dao = new UpdateDaoImpl();
        Student stu=new Student("8","蓝猫",20,2,98);
        dao.addStudent(stu);
    }
    
    @Test
    /*测试查询所有学生信息*/
    public void testfindAllStudent() {
        UpdateDao dao = new UpdateDaoImpl();
        List<Student> list = null;
        list = dao.findAllStudent();
        for (Student stu : list) {
            System.out.println(stu);
        }
    }
}

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