package dao;

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

public class BaseDao {
    public static Connection conn(){
        Connection conn = null;
        try {
            Class.forName("oracle.jdbc.driver.OracleDriver");
            conn = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl","scott","tiger");
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return conn;
    }
    public static void close(ResultSet rs,Statement stm,Connection conn){
            try {
                if(rs!=null){
                    rs.close();
                }
                if(stm!=null){
                    stm.close();
                }
                if(conn!=null){
                    conn.close();
                }
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }    
    }
}

package dao;

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

import entity.Student;

public class StudentDao {
        public static List<Student> queryAll(){
            Connection conn = null;
            PreparedStatement pstm = null;
            ResultSet rs = null;
            List list = new ArrayList();
            
            try{
                conn = BaseDao.conn();
                String sql = "select * from studentinfo";
                pstm = conn.prepareStatement(sql);
                rs=pstm.executeQuery();
                while(rs.next()){
                    Student stu = new Student();
                    stu.setStuno(rs.getString(1));
                    stu.setStuname(rs.getString(2));
                    stu.setSex(rs.getString(3));
                    stu.setStuage(rs.getInt(4));
                    list.add(stu);
                }    
            }catch(Exception e){
                e.printStackTrace();
            }finally{
                BaseDao.close(rs, pstm, conn);
            }
            return list;
        }
}

package entity;

public class Student {
    private String stuno;
    private String stuname;
    private String sex;
    private int stuage;
    public String getStuno() {
        return stuno;
    }
    public void setStuno(String stuno) {
        this.stuno = stuno;
    }
    public String getStuname() {
        return stuname;
    }
    public void setStuname(String stuname) {
        this.stuname = stuname;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    public int getStuage() {
        return stuage;
    }
    public void setStuage(int stuage) {
        this.stuage = stuage;
    }
}