JDBC使用模板

package com.jdbc;
import com.domain.User;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;


//JDBC改进:JDBC编码的模板

    public class iii {

        public static void main(String[] args) {
            Connection conn = null;
            Statement stmt = null;
            ResultSet rs = null;
            try{
                Class.forName("com.mysql.jdbc.Driver");
                conn = DriverManager.getConnection("jdbc:mysql:///day15?user=root&password=sorry");
                stmt = conn.createStatement();
                rs = stmt.executeQuery("select id,name,password,email,birthday from users");
                List users = new ArrayList();
                while(rs.next()){
                    //封装:把结果搞到实体Bean（Domain），模型
                    //数据库类型和Java类型的对应关系：固定的
                    User user = new User();
                    user.setId(rs.getInt("id"));
                    user.setName(rs.getString("name"));
                    user.setPassword(rs.getString("password"));
                    user.setEmail(rs.getString("email"));
                    user.setBirthday(rs.getDate("birthday"));
                    users.add(user);
                }

                for(User u:users)
                    System.out.println(u);
            }catch(Exception e){
                throw new RuntimeException(e);
            }finally{// final finally finalize区别
                if(rs!=null){
                    try {
                        rs.close();
                    } catch (SQLException e) {
                        e.printStackTrace();
                    }
                    rs = null;
                }
                if(stmt!=null){
                    try {
                        stmt.close();
                    } catch (SQLException e) {
                        e.printStackTrace();
                    }
                    stmt = null;
                }
                if(conn!=null){
                    try {
                        conn.close();
                    } catch (SQLException e) {
                        e.printStackTrace();
                    }
                    conn = null;
                }
            }
        }
    }