JdbcUtils

JdbcUtils

package com.dwx.jabcstudy;

import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

public class JdbcUtils {
    //提升作用域
    private static String driver = null;
    private static String url = null;
    private static String username = null;
    private static String password = null;
    // 这是一个静态代码块 因此 再倒入这个类时 只会加载一次
    static {
        try{
            InputStream in = JdbcUtils.class.getClassLoader().getResourceAsStream("db.properties"); //这里是去获取配置文件
            Properties properties = new Properties(); //这是一个流
            properties.load(in); //加载配置文件
           driver = properties.getProperty("driver");//这就是获取配置文件中数值的方法
           url =  properties.getProperty("url");
           username =  properties.getProperty("username");
           password =  properties.getProperty("password");
           Class.forName(driver);//加载mysql
        }catch (Exception e){
            System.out.println("出错了!!!");
        }finally {

        }
    }
    //获取链接
    //方法会返回一个Connection类型的数据
    public static Connection getConnection() throws Exception {
        return DriverManager.getConnection(url, username, password);
    }
    //释放资源
    public static void release(Connection connection, Statement statement, ResultSet resultSet) throws SQLException {
        if(resultSet!=null){
            try {
                resultSet.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        if(statement!=null){
            statement.close();
        }
        if (connection!=null){
            connection.close();
        }
    }
}

注意：这个JdbcUtils工具类需要放在调用它的类的同一个包下

db.properties

driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/demo?useUnicode=true&characterEnconding=utf8&useSSL=true
username=dwx
password=123456

注意：这个配置需要放在src目录下

操作实例

package com.dwx.jabcstudy;

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

public class JDBCSecond {
    public static void main(String[] args) throws Exception {
        Connection connection = null;
        Statement statement = null;
        ResultSet resultSet = null;
        try {
            connection = JdbcUtils.getConnection();//获取数据库链接
            statement = connection.createStatement();//获得sql的执行对象
            String sql = "INSERT INTO dwx(id,`name`,`sex`)" +
                    "VALUES(6,'kti','m')"; //有了sql命令
            int i = statement.executeUpdate(sql);//将sql丢到sql执行对象里边就行了
            if(i>0){
                System.out.println("插入成功!!!");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            JdbcUtils.release(connection,statement,resultSet); //调用工具类来释放资源
        }

    }
}

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