数据库工具类第一版（DBUtils）

数据库工具类第一版（DBUtils）

只是将一些重复的代码封装到一个类中去：

代码：

实体类User
package test_path.entity;

public class User {
    //专门用来映射mysql数据库的t_user映射的。建议其中的属性名或成员变量和表中的字段名保持一致
    private Integer id;
    private String uname;
    private String upwd;
    private String birth;

    public User() {
    }

    public User(Integer id, String uname, String upwd, String birth) {
        this.id = id;
        this.uname = uname;
        this.upwd = upwd;
        this.birth = birth;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", uname='" + uname + '\'' +
                ", upwd='" + upwd + '\'' +
                ", birth='" + birth + '\'' +
                '}';
    }
}

工具类
package test_path;

import test_path.entity.User;

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 TestUtilsOne {
    public static void main(String[] args) {
        Connection connection=JDBCUtilsOne.getConnection();
        String sql="select * from t_user";
        PreparedStatement ps = null;
        ResultSet rs = null;
        List<User> list= null;
        try {
            ps = connection.prepareStatement(sql);
            rs = ps.executeQuery();
            list = new ArrayList<>();
            while(rs.next()){
                User user=new User(rs.getInt(1),rs.getString(2),rs.getString(3),rs.getString(4));
                list.add(user);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        for(User u:list){
            System.out.println(u);
        }
        JDBCUtilsOne.close(connection,ps,rs);
    }
}

测试工具类代码：
package test_path;

import test_path.entity.User;

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 TestUtilsOne {
    public static void main(String[] args) {
        Connection connection=JDBCUtilsOne.getConnection();
        String sql="select * from t_user";
        PreparedStatement ps = null;
        ResultSet rs = null;
        List<User> list= null;
        try {
            ps = connection.prepareStatement(sql);
            rs = ps.executeQuery();
            list = new ArrayList<>();
            while(rs.next()){
                User user=new User(rs.getInt(1),rs.getString(2),rs.getString(3),rs.getString(4));
                list.add(user);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        for(User u:list){
            System.out.println(u);
        }
        JDBCUtilsOne.close(connection,ps,rs);
    }
}