Java数据库连接jdbc
导入java包
1、根目录，新建一个lib目录（Dire）
2、将jar包放入lib目录下
3、File -> Project Structure（项目结构）
4、Libraries-> + ->java->找到项目的lib目录
5、Apply->OK
使用JDBC的步骤如下：
//加载数据库驱动 → 建立数据库连接（Connection） → 创建执行SQL语句的Statement对象 → 处理执行结果（ResultSet） → 释放资源
Java加载数据库驱动通常是使用Class类的静态方法forName()，语法格式如下：
Class.forName(String driverManager)
eg:Class.forName("com.mysql.jdbc.Driver" );
创建statement对象
try {
Statement statement = conn.createStatement();
} catch (SQLException e) {
e.printStackT\frace();
}
创建数据库
try {
String sql1="drop database if exists test";
String sql2="create database test";
statement.executeUpdate(sql1);//执行sql语句
statement.executeUpdate(sql2);
} catch (SQLException e) {
e.printStackT\frace();
}
创建表
try {
statement.executeUpdate("use test");//选择在哪个数据库中操作
String sql = "create table table1(" +
"column1 int not null, " +
"column2 varchar(255)" +
")";
statement.executeUpdate(sql);
} catch (SQLException e) {
e.printStackT\frace();
}
释放资源
//Jdbc程序运行完后，切记要释放程序在运行过程中创建的那些与数据库进行交互的对象，这些对象通常是 ResultSet , Statement 和 Connection 对象。
//特别是Connection对象，它是非常稀有的资源，用完后必须马上释放，如果Connection不能及时、正确的关闭，极易导致系统宕机。
//Connection的使用原则是尽量晚创建，尽量早的释放。
finally {
try {
if(statement!=null)
statement.close();
if(conn!=null)
conn.close();
} catch (SQLException e) {
e.printStackT\frace();
}
}
对数据库增删改查案例：
StudentDaoImpl.java的内容
package com.dx.test07.jdbc;
import java.sql.Connection;
import java.sql.Timestamp;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
public class StudentDaoImpl extends BaseDao implements StudentDao{
@Override
//查询
public void getStudentList(){
try {
connection = getConnection(); //获取数据库连接
String sql = "select * from `student`"; //sql语句
ps = connection.prepareStatement(sql); //语句对象
rs= ps.executeQuery(); //执行sql语句
while (rs.next()){ //rs 用于存放返回的数据集合
int studentNo =rs.getInt( "studentNo");
String loginPwd =rs.getString( "LoginPwd");
String studentName =rs.getString( "StudentName");
String studentemail =rs.getString("Email");
Date date = rs.getDate("BornDate");
System.out.println(studentNo+"\t\t"+loginPwd+"\t\t"+studentName +"\t\t"+ studentemail+"\t\t"+date);
}
}
catch (Exception e){
e.printStackTrace();
}
finally {
close(connection,ps,rs);
}
}
//String类型转换Timestamp时间戳
public Timestamp convertTime(String dateString){
DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
try {
Date date = dateFormat.parse(dateString);
return new Timestamp(date.getTime());
} catch (ParseException e) {
e.printStackTrace();
return null;
}
}
//增加
public void addStudent(Student student) {
try{
connection = getConnection();
String sql = "INSERT INTO student values(null,?,?,?,?,?,?,?,?,?)";
ps= connection.prepareStatement(sql);
ps.setString(1, student.getLoginPwd());
ps.setString(2, student.getStudentName());
ps.setInt(3, student.getSex());
ps.setInt(4, student.getGradeId());
ps.setString(5, student.getPhone());
ps.setString(6, student.getAddress());
ps.setTimestamp(7,convertTime("2024-09-25 09:08:01"));
ps.setString(8,student.getEmail());
ps.setString(9,student.getIdentityCard());
int count = ps.executeUpdate();
if(count > 0){
System.out.println("添加成功！！");
}else System.out.println("添加失败！！");
}catch (Exception e){
e.printStackTrace();
}finally {
close(connection,ps,rs);
}
}
//删除
public void deleteStudent(int Stu_Num){
connection = getConnection();
String sql = "DELETE FROM `student` WHERE `StudentNo`= ? ;";
try {
ps= connection.prepareStatement(sql);
ps.setInt(1,Stu_Num);
int count = ps.executeUpdate();
if(count > 0){
System.out.println("添加成功！！");
}else System.out.println("添加失败！！");
}catch (Exception e){
e.printStackTrace();
}finally {
close(connection,ps,rs);
}
}
//更改
public void updataStudent(int StudentNo, String LoginPwd, String StudentName, int Sex, int GradeId, String Phone, String Address, String BornDate, String Email, String IdentityCard){
connection = getConnection();
String sql = "UPDATE `student` SET `LoginPwd`=?,`StudentName`=?,`Sex`=?,`GradeId`=?,`Phone`=?,`Address`=?,`BornDate`=?,`Email`=?,`IdentityCard`=? WHERE `StudentNo`= ?";
try {
ps= connection.prepareStatement(sql);
ps.setString(1,LoginPwd);
ps.setString(2,StudentName);
ps.setInt(3,Sex);
ps.setInt(4,GradeId);
ps.setString(5,Phone);
ps.setString(6,Address);
ps.setTimestamp(7,convertTime(BornDate));
ps.setString(8,Email);
ps.setString(9,IdentityCard);
ps.setInt(10,StudentNo);
int count = ps.executeUpdate();
if(count > 0){
System.out.println("添加成功！！");
}else System.out.println("添加失败！！");
}catch (Exception e){
e.printStackTrace();
}finally {
close(connection,ps,rs);
}
}
public static void main(String[] args) {
//查询
new StudentDaoImpl().getStudentList();
System.out.println("----------------------------------");
//增加
Student stu = new Student();
stu.setLoginPwd("123456");
stu.setStudentName("武大郎");
stu.setSex(1);
stu.setGradeId(3);
stu.setPhone("15099567049");
stu.setAddress("天山区天山路");
stu.setEmail("1850534869@qq.com");
stu.setIdentityCard("15156156156161511717818");
new StudentDaoImpl().addStudent(stu);
//删除
new StudentDaoImpl().deleteStudent(1019);
//更改邮箱
//int StudentNo
//String LoginPwd
//String StudentName
//int Sex
//int GradeId
//String Phone
//String Address
//String BornDate
//String Email
//String IdentityCard
new StudentDaoImpl().updataStudent(1010,"123123","郭胧演",1,3,"15099555555","新疆乌鲁木齐","2001-10-01 09:10:16","1850534869@qq.com","411422200102010736");
System.out.println("----------------------------------");
new StudentDaoImpl().getStudentList();
}
}
实现一个名为StudentDao.java的接口
package com.dx.test07.jdbc;
import java.util.Date;
public interface StudentDao {
/**
* 获取学生的数据
* */
public void getStudentList();
public void addStudent(Student student);
public void deleteStudent(int studentNO);
public void updataStudent(int StudentNo,String LoginPwd,String StudentName,int Sex,int GradeId,String Phone,String Address,String BornDate,String Email,String IdentityCard);
}
//int StudentNo
//String LoginPwd
//String StudentName
//int Sex
//int GradeId
//String Phone
//String Address
//Date BornDate
//String Email
//String IdentityCard
Student.java类的定义
package com.dx.test07.jdbc;
import java.util.Date;
public class Student {
//在数据库中若为varchar类型，在java中写成String类型;
private int StudentNo;
private String LoginPwd;
private String StudentName;
private int Sex;
private int GradeId;
private String Phone;
private String Address;
private Date BornDate;
private String Email;
private String IdentityCard;
//声明get set方法
public int getStudentNo() {
return StudentNo;
}
public void setStudentNo(int studentNo) {
StudentNo = studentNo;
}
public String getLoginPwd() {
return LoginPwd;
}
public void setLoginPwd(String loginPwd) {
LoginPwd = loginPwd;
}
public String getStudentName() {
return StudentName;
}
public void setStudentName(String studentName) {
StudentName = studentName;
}
public int getSex() {
return Sex;
}
public void setSex(int sex) {
Sex = sex;
}
public int getGradeId() {
return GradeId;
}
public void setGradeId(int gradeId) {
GradeId = gradeId;
}
public String getPhone() {
return Phone;
}
public void setPhone(String phone) {
Phone = phone;
}
public String getAddress() {
return Address;
}
public void setAddress(String address) {
Address = address;
}
public Date getBornDate() {
return BornDate;
}
public void setBornDate(Date bornDate) {
BornDate = bornDate;
}
public String getEmail() {
return Email;
}
public void setEmail(String email) {
Email = email;
}
public String getIdentityCard() {
return IdentityCard;
}
public void setIdentityCard(String identityCard) {
IdentityCard = identityCard;
}
}
BaseDao.java 用来提供数据库连接和返回的
package com.dx.test07.jdbc;
import java.sql.*;
public class BaseDao {
//数据库连接对象
public Connection connection;
//创建执行语句的
public PreparedStatement ps;
//获取结果集合
public ResultSet rs;
//获得数据库连接
public Connection getConnection(){
String driver = "com.mysql.cj.jdbc.Driver";// 驱动类
String url = "jdbc:mysql://localhost:3306/myschool_db"; //此处是随机命名的一个数据库
String name = "root";
String passwd = "root";
加载驱动类
try{
//Java加载数据库驱动通常是使用Class类的静态方法forName()
Class.forName(driver);
//获得数据库连接并返回
System.out.println("连接成功！！");
return DriverManager.getConnection(url,name,passwd);
}catch (Exception e){
e.printStackTrace();
System.out.println("连接失败！！");
return null;
}
}
public void close(Connection connection,PreparedStatement ps, ResultSet rs){
try {
if(rs!=null) rs.close();
if(ps!=null) ps.close();
if(connection!=null) connection.close();
}catch (Exception e){
e.printStackTrace();
}
}
public static void main(String[] args) {
//测试连接
new BaseDao().getConnection();
}
}
数据库参考如下
![数据结构const char *INSTNAME[]](https://i-blog.csdnimg.cn/direct/79560ad0a3124cfaadd6bd27261e84be.png)
