package com.j1702.model;
//定义类
public class Student {
private Integer id;
private String name;
private Integer age;
private String address;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}
package com.j1702.db;
import java.sql.*;
public class DBUtil {//创建工具类
private static final String URL="jdbc:mysql://127.0.0.1:3306/jdbc_test";
private static final String USER="root";
private static final String PASSWORD="123456";
//实例化一个链接对象conn
private static Connection conn=null;
static{//静态方法块
try {
//1， 加载驱动程序
Class.forName("com.mysql.jdbc.Driver");
//2， 获得数据库链接对象 conn
conn=DriverManager.getConnection(URL, USER, PASSWORD);//直接获得conn实例对象 或者用下面这种
//setConn(DriverManager.getConnection(URL, USER, PASSWORD));//通过set方法获得conn实例对象
} catch (Exception e) {
e.printStackTrace();
}
}
public static Connection getConn() {
return conn;
}
public static void setConn(Connection conn) {
DBUtil.conn = conn;
}
}
package com.j1702.dao;
import java.sql.*;
import java.util.*;
import com.j1702.db.DBUtil;
import com.j1702.model.Student;
public class StudentDao {
//1、增
public static void add(Student stu) throws Exception{
//通过工具类，获取数据库链接对象
Connection conn=DBUtil.getConn();
//创建 sql 语句(?占坑)
String sql="insert Student (name,age,address) values(?,?,?)";
//创建欲加载的sql语句执行对象
PreparedStatement ptmt=conn.prepareStatement(sql);
//给名字赋值
ptmt.setString(1,stu.getName());
//给年龄赋值
ptmt.setInt(2, stu.getAge());
//给地址赋值
ptmt.setString(3, stu.getAddress());
//执行sql语句
ptmt.execute();
}
//2、删
public static void delete(Integer id) throws Exception{
//通过工具类，获取数据库链接对象
Connection conn=DBUtil.getConn();
//创建 sql 语句(?占坑)
String sql="delete from Student where id=?";
//创建欲加载的sql语句执行对象
PreparedStatement ptmt=conn.prepareStatement(sql);
//给id赋值
ptmt.setInt(1,id);
//执行sql语句
ptmt.execute();
}
//3、改
public static void update(Student stu,Integer id) throws Exception{
//通过工具类，获取数据库链接对象
Connection conn=DBUtil.getConn();
//创建 sql 语句(?占坑)
String sql="update Student set name=?,age=?,address=? where id=?";
//创建欲加载的sql语句执行对象
PreparedStatement ptmt=conn.prepareStatement(sql);
//给名字赋值
ptmt.setString(1,stu.getName());
//给年龄赋值
ptmt.setInt(2, stu.getAge());
//给地址赋值
ptmt.setString(3, stu.getAddress());
//给id赋值
ptmt.setInt(4, id);
//执行sql语句
ptmt.execute();
}
//4、查所有
public static void query() throws Exception{
//通过工具类，获取数据库链接对象
Connection conn=DBUtil.getConn();
//创建 sql 语句(?占坑)
String sql="select * from Student";
//创建欲加载的sql语句执行对象（在只执行一句sql语句时使用该语句，需要循环执行sql语句时用另一种）
Statement stmt=conn.createStatement();
//用结果集ResultSet创建对象来接收sql语句返回的数据集
ResultSet rs=stmt.executeQuery(sql);
while (rs.next()) {
System.out.println("id:"+rs.getInt("id")+"\tname:"+rs.getString("name")+
"\tage:"+rs.getInt("age")+"\taddress:"+rs.getString("address"));
}
}
//5、查某个
public static void queryWithId(Integer id) throws Exception{
//通过工具类，获取数据库链接对象
Connection conn=DBUtil.getConn();
//创建 sql 语句(?占坑)
String sql="select * from Student where id=?";
//创建欲加载的sql语句执行对象
PreparedStatement ptmt=conn.prepareStatement(sql);
ptmt.setInt(1, id);
ResultSet rs=ptmt.executeQuery();
while (rs.next()) {
System.out.println("id:"+rs.getInt("id")+"\tname:"+rs.getString("name")+
"\tage:"+rs.getInt("age")+"\taddress:"+rs.getString("address"));
}
}
//6、条件查询
public static void queryWithParam(List<Map<String, Object>> param) throws Exception{
Connection conn=DBUtil.getConn();//得到链接对象
StringBuffer sql=new StringBuffer();
sql.append("select * from Student where 1=1");
for(Map<String, Object>map:param){
sql.append(" and "+map.get("key")+" = ‘"+map.get("value") + "‘");
}
PreparedStatement ptmt=conn.prepareStatement(sql.toString());
ResultSet rs=ptmt.executeQuery();
while(rs.next()){
System.out.println("id:"+rs.getInt("id")+"\tname:"+rs.getString("name")+
"\tage:"+rs.getInt("age")+"\taddress:"+rs.getString("address"));
}
}
//7、按包含某个字符查询
public static void queryWithChar(List<Map<String, Object>> param) throws Exception{
Connection conn=DBUtil.getConn();//得到链接对象
StringBuffer sql=new StringBuffer();
sql.append("select * from Student where 1=1");
for(Map<String, Object>map:param){
sql.append(" and "+map.get("key")+" like ‘%"+map.get("value") + "%‘");
}
PreparedStatement ptmt=conn.prepareStatement(sql.toString());
ResultSet rs=ptmt.executeQuery();
while(rs.next()){
System.out.println("id:"+rs.getInt("id")+"\tname:"+rs.getString("name")+
"\tage:"+rs.getInt("age")+"\taddress:"+rs.getString("address"));
}
}
}
package com.j1702.action;
import java.util.List;
import java.util.Map;
import com.j1702.dao.StudentDao;
import com.j1702.model.Student;
//这一层是Controller 层:是为view层和model层服务的
public class StudentAction {
//向数据库中插入一条数据
public static void insert(Student stu) throws Exception{
StudentDao.add(stu);
}
//根据传入的id删除学生
public static void delete(Integer id) throws Exception{
StudentDao.delete(id);
}
//更新数据
public static void update(Student stu,Integer id) throws Exception{
StudentDao.update(stu,id);
}
//查找数据
public static void find(List<Map<String, Object>> param) throws Exception{
StudentDao.queryWithParam(param);
}
//按某个字符查询
public static void findOfChar(List<Map<String, Object>> param) throws Exception{
StudentDao.queryWithChar(param);
}
//查看详情
public static void show() throws Exception{
StudentDao.query();
}
}
package com.j1702.view;
import java.util.*;
import com.j1702.model.Student;
import com.j1702.action.StudentAction;
//注意：以下例子并不完整，存在许多BUG和不合理之处。
public class TestView {
public static void main(String[] args) throws Exception {
//编程以终端为view层，实现数据的 增、删、改、查的操作
/**
* 请输入你要做的操作：A 添加，D 删除，U 更新，F 查询，exit 退出
*
* 请输入插入数据的name age address
*
* 请输入你要做的操作：A 添加，D 删除，U 更新，F 查询，exit 退出
* */
action();
}
public static void action() throws Exception{
while(true){
System.out.println("A 添加 D 删除 U 更新 F 查询 E 退出\n请选择您想要进行的操作：");
Scanner scan0=new Scanner(System.in);
String key0=scan0.next();
//scan0.close();
switch (key0) {
case "A":
Add();
break;
case "D":
Del();
break;
case "U":
UpDat();
break;
case "F":
Find();
break;
case "E":
return;
default:
System.out.println("对不起！没有你输入的选项，请重写输入！");
break;
}
}
}
//添加学生
public static void Add() throws Exception{
Student stu=creatCode();
StudentAction.insert(stu);
}
//删除学生
public static void Del() throws Exception{
System.out.println("请输入你要删除的学生的id号：");
Scanner scan4=new Scanner(System.in);
int id=scan4.nextInt();
StudentAction.delete(id);
scan4.close();
}
//替换学生
public static void UpDat() throws Exception{
Student stu=creatCode();//创建Student
System.out.println("请输入你要修改的学生的id号：");
Scanner scan5=new Scanner(System.in);
int id=scan5.nextInt();
StudentAction.update(stu, id);
scan5.close();
}
//查找学生
public static void Find() throws Exception{
System.out.println("该数据库的字段有：id name age address");
List<Map<String, Object>> li=new ArrayList<Map<String,Object>>();
a:
while (true) {
Map<String, Object> map=mp();
li.add(map);
b:
while (true) {
System.out.println("请选择： 1，继续输入查询条件 2，开始查询");
Scanner scan8=new Scanner(System.in);
int key2=scan8.nextInt();
switch (key2) {
case 1:
continue a;
case 2:
break a;
default:
System.out.println("对不起没有您输入的选项！请重新选择！");
continue b;
}
}
}
//StudentAction.find(li);//多条件查询
StudentAction.findOfChar(li);//模糊多条件查询
}
//创建map对象
public static Map<String, Object> mp(){
Map<String,Object> map=new HashMap<String,Object>();
System.out.println("请输入您想要查询的字段：");
Scanner scan7=new Scanner(System.in);
String key1=scan7.next();
map.put("key",key1);
System.out.println("请输入您想要查询字段中的值：");
Scanner scan6=new Scanner(System.in);
String input=scan6.next();
if(key1.equals("age") | key1.equals("id")){
Integer integer=Integer.parseInt(input);
map.put("value", integer);
}else if(key1.equals("name") | key1.equals("address")){
map.put("value", input);
}
return map;
}
//创建新学生对象
public static Student creatCode(){
Student stu=new Student();
System.out.println("请输入该学生的姓名：");
Scanner scan1=new Scanner(System.in);
String name=scan1.next();
stu.setName(name);
//scan1.close();
System.out.println("请输入该学生的年龄：");
Scanner scan2=new Scanner(System.in);
int age=scan2.nextInt();
stu.setAge(age);
//scan2.close();
System.out.println("请输入该学生的地址：");
Scanner scan3=new Scanner(System.in);
String address=scan3.next();
stu.setAddress(address);
//scan3.close();
return stu;
}
}
时间： 2024-10-11 00:07:32