JDBC练习_select语句

练习：

定义一个方法，查询emp表的数据将其封装为对象，然后装在集合，返回。
1.定义Emp磊
2.定义方法 public List findAll(){}
3.实现方法 select * from emp;

代码实现

package cn.lhy.Test;

import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class Test {
    public static void main(String[] args) throws Exception {

        List<Emp> all = findAll();
        all.forEach(emp -> System.out.println(emp));

    }

    /**
     * 查询所有emp对象
     * @return
     */
    public static List<Emp> findAll() throws Exception {
        ArrayList<Emp> list = new ArrayList<>();
        Class.forName("com.mysql.cj.jdbc.Driver");
        Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "root");
        String sql = "select * from emp";
        Statement stmt = conn.createStatement();
        ResultSet rs = stmt.executeQuery(sql);

        while(rs.next()){
            int id = rs.getInt("id");
            String ename = rs.getString("ename");
            int job_id = rs.getInt("job_id");
            int mgr = rs.getInt("mgr");
            Date joindate = rs.getDate("joindate");
            int salary = rs.getInt("salary");
            int bonus = rs.getInt("bonus");
            int dept_id = rs.getInt("dept_id");

            list.add(new Emp(id,ename,job_id,mgr,joindate,salary,bonus,dept_id));
        }

        conn.close();
        stmt.close();
        return list;
    }
}

emp类

package cn.lhy.Test;

import java.util.Date;

public class Emp {
    int id;
    String ename;
    int job_id;
    int mgr;
    Date joindate;
    int salary;
    int bonus;
    int dept_id;

    public Emp(int id, String ename, int job_id, int mgr, Date joindate, int salary, int bonus, int dept_id) {
        this.id = id;
        this.ename = ename;
        this.job_id = job_id;
        this.mgr = mgr;
        this.joindate = joindate;
        this.salary = salary;
        this.bonus = bonus;
        this.dept_id = dept_id;
    }

    public Emp() {

    }

    @Override
    public String toString() {
        return "Emp{" +
                "id=" + id +
                ", ename='" + ename + '\'' +
                ", job_id=" + job_id +
                ", mgr=" + mgr +
                ", joindate=" + joindate +
                ", salary=" + salary +
                ", bonus=" + bonus +
                ", dept_id=" + dept_id +
                '}';
    }
}