第一步：在项目中新建一个名称叫lib的文件夹，然后将下载的MySQL连接jar包存入到这个lib文件夹中并配置环境
第二步：编写代码，连接数据库并操作数据库中某个表里的数据
①：基本操作
//1.注册驱动
Class.forName("com.mysql.jdbc.Driver");
//2.获得连接
String url = "jdbc:mysql:///java";
String username = "root";
String password = "root";
Connection connection = DriverManager.getConnection(url, username, password);
//3.获取发送SQL语句对象
Statement statement = connection.createStatement();
//4.编写SQL语句
String sql = "insert into student1 value(2,'lisi')";
statement.executeUpdate(sql);
//5.释放资源
statement.close();
connection.close();
②：防止SQL注入
Scanner sc = new Scanner(System.in);
System.out.println("请输入用户名：");
String userName = sc.nextLine();
System.out.println("请输入密码：");
String pwd = sc.nextLine();
// 1、注册驱动
Class.forName("com.mysql.jdbc.Driver");
// 2、获得连接
String url = "jdbc:mysql://localhost:3306/java";
String user = "root";
String password = "123456";
Connection connection = DriverManager
.getConnection(url, user, password);
// 3、获取发送SQL对象
String sql = "select * from db_user where userName = ? and password=?;";
PreparedStatement preparedStatement = connection.prepareStatement(sql);
// System.out.println(preparedStatement);
// 4、绑定参数，有多少个?绑定多少个参数值
preparedStatement.setString(1, userName);
preparedStatement.setString(2, pwd);
// System.out.println(preparedStatement);
// 5、执行SQL语句，并处理结果
ResultSet resultSet = preparedStatement.executeQuery();
if (resultSet.next()) {
System.out.println("用户名和密码正确，登录成功");
} else {
System.out.println("用户名或密码错误，登录失败");
}
// 6、释放资源:与关闭流的方式一样，先开的后关，后开的先关
resultSet.close();
preparedStatement.close();
connection.close();
sc.close();
}
③：编写一个DB工具类
import java.sql.*;
public class DBUtils {
static {
// 类加载，执行一次！
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
//1.获取连接
public static Connection getConnection(){
Connection connection = null;
try {
connection = DriverManager.getConnection("jdbc:mysql:///java", "root", "root");
} catch (SQLException e) {
e.printStackTrace();
}
return connection;
}
// 2.释放资源
public static void closeAll(Connection connection, Statement statement,
ResultSet resultSet) {
try {
if (resultSet != null) {
resultSet.close();
}
if (statement != null) {
statement.close();
}
if (connection != null) {
connection.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
需求：
public static void main(String[] args) throws ClassNotFoundException, SQLException {
/*
* 需求：在控制台输入用户名和密码，根据输入的用户名和密码在数据库中查询，如果用户名和密码在数据库中，提示登录成功，反之提示登录失败
*/
Scanner sc = new Scanner(System.in);
System.out.println("请输入用户名：");
String userName = sc.nextLine();
System.out.println("请输入密码：");
String pwd = sc.nextLine();
//1.注册驱动
//Class.forName("com.mysql.jdbc.Driver");
Connection connection = DBUtils.getConnection();
String sql = "SELECT * FROM db_user where user=? and pwd = ?";
PreparedStatement preparedStatement = connection.prepareStatement(sql);
preparedStatement.setString(1,userName);
preparedStatement.setString(2,pwd);
ResultSet resultSet = preparedStatement.executeQuery();
if (resultSet.next()){
System.out.println("用户名和密码正确，登录成功");
}else{
System.out.println("用户名或密码错误，登录失败");
}
// 6、释放资源:与关闭流的方式一样，先开的后关，后开的先关
DBUtils.closeAll(connection, preparedStatement, resultSet);
sc.close();
}
④：编写配置文件db.properties
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/java
username=root
password=123456
db工具类
public class DBUtils {
private static final Properties PROPERTIES = new Properties();//PROPERTIES是存储配置文件的集合
static {
InputStream is = DBUtils.class.getResourceAsStream("/db.properties");
try {
PROPERTIES.load(is);
Class.forName(PROPERTIES.getProperty("driver"));
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
public static Connection getConnection() {
Connection connection = null;
try {
connection = DriverManager.getConnection(PROPERTIES.getProperty("url"), PROPERTIES.getProperty("username"), PROPERTIES.getProperty("password"));
} catch (SQLException e) {
e.printStackTrace();
}
return connection;
}
public static void closeAll(Connection connection, Statement statement, ResultSet resultSet) {
try {
if (resultSet != null) {
resultSet.close();
}
if (statement != null) {
statement.close();
}
if (connection != null) {
connection.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
需求：
public static void main(String[] args) throws ClassNotFoundException, SQLException {
/*
* 需求：在控制台输入用户名和密码，根据输入的用户名和密码在数据库中查询，如果用户名和密码在数据库中，提示登录成功，反之提示登录失败
*/
Scanner sc = new Scanner(System.in);
System.out.println("请输入用户名：");
String userName = sc.nextLine();
System.out.println("请输入密码：");
String pwd = sc.nextLine();
//1.注册驱动
//Class.forName("com.mysql.jdbc.Driver");
Connection connection = DBUtils.getConnection();
String sql = "SELECT * FROM db_user where user=? and pwd = ?";
PreparedStatement preparedStatement = connection.prepareStatement(sql);
preparedStatement.setString(1,userName);
preparedStatement.setString(2,pwd);
ResultSet resultSet = preparedStatement.executeQuery();
if (resultSet.next()){
System.out.println("用户名和密码正确，登录成功");
}else{
System.out.println("用户名或密码错误，登录失败");
}
// 6、释放资源:与关闭流的方式一样，先开的后关，后开的先关
DBUtils.closeAll(connection, preparedStatement, resultSet);
sc.close();
}
