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 -_-      ---------------------------