web---jdbc工具类编写

JDBCUtils工具包

package com.jdbc.utils;

import java.io.FileReader;
import java.io.IOException;
import java.net.URL;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

public class JDBCUtils {
    
    private static String url;
    private static String user;
    private static String password;
    private static String driver;

    static {
    
        //创建Properties对象
        Properties properties = new Properties();
        //通过src路径下的文件获取
        ClassLoader classLoader = JDBCUtils.class.getClassLoader();
        URL res = classLoader.getResource("jdbc.properties");

        String path = res.getPath();

        try {
    
            System.out.println(path);
            properties.load(new FileReader(path));
            //获取赋值
            url = properties.getProperty("url");

            user = properties.getProperty("user");
            password = properties.getProperty("password");
            driver=properties.getProperty("driver");

            try {
    
                Class.forName(driver);
            } catch (ClassNotFoundException e) {
    
                e.printStackTrace();
            }

        } catch (IOException e) {
    
            e.printStackTrace();
        }
    }

    /** * 获取连接对象 * * @return */
    public static Connection getConnection() throws SQLException {
    
        //不想传递参数就配置文件
// String url = "jdbc:mysql://localhost:3306/monkey";
// String username = "root";
// String password = "123456789";
        return DriverManager.getConnection(url,user,password);
    }

    /** * 释放资源 * * @param stat * @param conn */
    public static void close(Statement stat, Connection conn) {
    
        if (stat != null) {
    
            try {
    
                stat.close();
            } catch (SQLException throwables) {
    
                throwables.printStackTrace();
            }
        }
        if (conn != null) {
    
            try {
    
                conn.close();
            } catch (SQLException throwables) {
    
                throwables.printStackTrace();
            }
        }
    }
}

jdbc.properties配置文件

url=jdbc:mysql://localhost:3306/monkey
user=root
password=123456789
driver=com.mysql.cj.jdbc.Driver

应用工具类

package com.jdbc;

import com.jdbc.utils.JDBCUtils;

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

public class JdbcDemo02 {
    
    public static void main(String[] args) {
    
        Connection conn = null;
        Statement stat = null;
        ResultSet resultSet = null;
        try {
    
            conn = JDBCUtils.getConnection();
            String sql = "update lmonkey_user set USER_PASSWORD = '123456789' where USER_ID=5555";
            String sql1 = "select * from lmonkey_user";
            stat = conn.createStatement();
            resultSet = stat.executeQuery(sql1);

            while (resultSet.next()) {
    
                String id = resultSet.getString("USER_ID");
                String name = resultSet.getString("USER_NAME");
                System.out.println(id + "\t" + name);

            }

            int i = stat.executeUpdate(sql);

            if (i > 0) {
    
                System.out.println("添加成功");
            } else {
    
                System.out.println("添加失败");
            }

        } catch (SQLException throwables) {
    
            throwables.printStackTrace();
        } finally {
    
            JDBCUtils.close(stat, conn);
        }

    }
}