JDBC_dao模式学习笔记

1.新建一个Dao的包，在里面声明一个接口，接口里声明数据库的访问规则

public interface StuDao {

   //1.查询
   void findAll();

   //2.添加
   void insert();

   //3.删除
   void delete();

   //4.修改
   void update();

}

2.新建一个Dao接口的实现类，具体实现接口里面的访问规则

public class StuDaoimpl implements StuDao{

   Connection conn=null;
   Statement sta=null;
   ResultSet res=null;
   @Override
   public void findAll() {

       try {
           //1.注册驱动
           conn = jdbcutil.getconn();
           //2.创建链接
           sta = conn.createStatement();
           //3.执行sql语句
           String sql = "select * from exam";
           res = sta.executeQuery(sql);
           //循环遍历数据
           while(res.next()) {
               int id= res.getInt("id");
               String name = res.getString("name");
               int chinese= res.getInt("chinese");
               int math= res.getInt("math");
               int english= res.getInt("english");
               System.out.println(id+"   "+name+"    "+chinese+"   "+math+"    "+english);
           }
       } catch (Exception e) {
           // TODO: handle exception
       }finally {
           jdbcutil.re(res, sta, conn);
       }

   }


        public void insert() {
           try {
               //1.注册驱动
               Connection conn = jdbcutil.getconn();
               //2.建立链接
               Statement sta = conn.createStatement();
               //3.执行数据库
               String sql = "insert into exam values(null,'姜小白',66,66,66)";
               int i=sta.executeUpdate(sql);

               if(i>0) {
                   System.out.println("添加成功");
               }else {
                   System.out.println("添加失败");
               }
           } catch (Exception e) {
               // TODO: handle exception
           }finally {
               jdbcutil.re(sta, conn);
           }

   }

        public void delete() {
           try {
               //1.注册驱动
               conn = jdbcutil.getconn();
               //2.创建链接对象Statement
               sta = conn.createStatement();
               //3.执行sql语句
               String sql = "delete from exam where id=10";
               int i = sta.executeUpdate(sql);

               if(i>0) {
                   System.out.println("删除成功");
               }else {
                   System.out.println("删除失败");
               }
           } catch (Exception e) {

           }finally {
               jdbcutil.re(sta, conn);
           }
        }

        public void update() {
           try {
               //1.注册驱动
               conn = jdbcutil.getconn();
               //2.创建连接对象Statement
               sta = conn.createStatement();
               //3.执行sql语句
               String sql = "update exam set name='老王',chinese=100,math=60,english=50 where id=8";
               int i=sta.executeUpdate(sql);
               if(i>0) {
                   System.out.println("更新成功");
               }else {
                   System.out.println("更新失败");
               }
           } catch (Exception e) {
               // TODO: handle exception
           }finally {
               jdbcutil.re(sta, conn);
           }

        }

}

3.新建一个test来实现测试

public class jdbctest {

public void findAllTest() {

       StuDao dao=new StuDaoimpl();
       dao.findAll();
   }


   public void insert() {
       StuDao dao=new StuDaoimpl();
       dao.insert();
   }

   public void delete() {
       StuDao dao=new StuDaoimpl();
       dao.delete();
   }
   @Test
   public void update() {
       StuDao dao=new StuDaoimpl();
       dao.update();

   }
}

JDBC_dao模式学习笔记

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