增删改查---体现面向对象思想

Posted 2021-12-23 king-boy

　　

package dao;

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

import domain.Person;
import util.JDBCUtil;

/**
 * 测试表的dao类
 * @author ASUS
 *
 */
public class PersonDao 
    
    

    /**
     * insert
     */
    public void insert(Person p) 
        Connection conn=null;
        Statement st=null;
        try 
            
            conn=JDBCUtil.openConnection();
            //创建st对象
            st=conn.createStatement();
            String sql="insert persons(name,age) values(‘"+p.getName()+"‘,"+p.getAge()+")";
            st.execute(sql);
            
        catch(Exception e) 
            e.printStackTrace();
        
        finally 
            JDBCUtil.closeStatement(st);
            JDBCUtil.closeConnection(conn);
        
    
    
    /**
     * update
     */
    public void update(Person p) 
        Connection conn=null;
        Statement st=null;
        try 
            conn=JDBCUtil.openConnection();
            
            //创建st对象
            st=conn.createStatement();
            String sql="update persons set name=‘"+p.getName()+"‘,age="+p.getAge()+" where id="+p.getId();
            st.execute(sql);
            
        catch(Exception e) 
            e.printStackTrace();
        
        finally 
            JDBCUtil.closeStatement(st);
            JDBCUtil.closeConnection(conn);
        
    
    
    /**
     * delete
     */
    public void insertById(Integer id) 
        Connection conn=null;
        Statement st=null;
        try 
            
            conn=JDBCUtil.openConnection();
            //创建st对象
            st=conn.createStatement();
            String sql="delete from persons where id = "+id;
            st.execute(sql);
            
        catch(Exception e) 
            e.printStackTrace();
        
        finally 
            JDBCUtil.closeStatement(st);
            JDBCUtil.closeConnection(conn);
        
    
    
    /**
     * select
     */
    public Person findById(Integer id) 
        Connection conn=null;
        Statement st=null;
        ResultSet rs=null;
        try 
            
            conn=JDBCUtil.openConnection();
            //创建st对象
            st=conn.createStatement();
            String sql="select * from persons where id = "+id;
            rs=st.executeQuery(sql);
            if(rs.next()) 
                Person p = new Person();
                p.setId(rs.getInt("id"));
                p.setName(rs.getString("name"));
                p.setAge(rs.getInt("age"));
                return p;
            
            
        catch(Exception e) 
            e.printStackTrace();
        
        finally 
            JDBCUtil.closeResultSet(rs);
            JDBCUtil.closeStatement(st);
            JDBCUtil.closeConnection(conn);
        
        return null;
    
    
    /**
     * select
     */
    public List<Person> findAll() 
        Connection conn=null;
        Statement st=null;
        ResultSet rs=null;
        try 
            
            conn=JDBCUtil.openConnection();
            //创建st对象
            st=conn.createStatement();
            String sql="select * from persons";
            rs=st.executeQuery(sql);
            List<Person> persons=new ArrayList<Person>();
            Person p = null;
            while(rs.next()) 
                p = new Person();
                p.setId(rs.getInt("id"));
                p.setName(rs.getString("name"));
                p.setAge(rs.getInt("age"));
                persons.add(p);
            
            return persons;
        catch(Exception e) 
            e.printStackTrace();
        
        finally 
            JDBCUtil.closeResultSet(rs);
            JDBCUtil.closeStatement(st);
            JDBCUtil.closeConnection(conn);
        
        return null;
    
    

public class PersonDao

package domain;

/**
 * Person
 * @author ASUS
 *
 */
public class Person 
    private Integer id;
    private String name;
    private int age;
    public Integer getId() 
        return id;
    
    public void setId(Integer id) 
        this.id = id;
    
    public String getName() 
        return name;
    
    public void setName(String name) 
        this.name = name;
    
    public int getAge() 
        return age;
    
    public void setAge(int age) 
        this.age = age;
    
    
    

public class PersonDao

package util;

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

/**
 * 工具类
 * @author ASUS
 *
 */
public class JDBCUtil 
    /**
     * 开启连接
     * @return
     */
    public static Connection openConnection() 
        try 
            //获得连接
            String url="jdbc:mysql://localhost:3306/mytest?serverTimezone=UTC";
            String username="root";
            String password="wang18339401841.";
            return DriverManager.getConnection(url, username, password);
        catch (Exception e) 
            e.printStackTrace();
        
        return null;
    
    
    /**
     * 关闭连接
     * @param conn
     */
    public static void closeConnection(Connection conn) 
        try 
            if(conn!=null&& !conn.isClosed())
                conn.close();
         catch (SQLException e) 
            e.printStackTrace();
        
    
    
    /**
     * 关闭语句
     * @param conn
     */
    public static void closeStatement(Statement st) 
        try     
            if(st!=null&& !st.isClosed())
                st.close();
         catch (SQLException e) 
            e.printStackTrace();
        
    
    
    /**
     * 关闭ResultSet
     * @param conn
     */
    public static void closeResultSet(ResultSet rs) 
        try     
            if(rs!=null&& !rs.isClosed())
                rs.close();
         catch (SQLException e) 
            e.printStackTrace();
        
    

public class JDBCUtil

package Jdbc;

import dao.PersonDao;
import domain.Person;

public class App 
    public static void main(String[] args) 
        PersonDao dao=new PersonDao();
//        Person p = new Person();
//        p.setName("tomaslee");
//        p.setAge(15);
        //dao.insert(p);
        
//        List<Person> list = dao.findAll();
//        for(Person p: list)
//            System.out.println(p.getId()+","+p.getName());
//        
        Person p=new Person();
        p.setId(1);
        p.setName("king");
        p.setAge(10);
        dao.update(p);
        System.out.println("over");
    

public class App