抽取JDBC工具类

JDBCUtils

import java.io.FileReader;
import java.io.IOException;
import java.net.URL;
import java.sql.*;
import java.util.Properties;

public class JDBCUtil {
    /**
     * 抽取jdbc工具类
     * 1. 抽取注册驱动
     * 2. 抽取获取连接对象
     * 3. 抽取关闭方法，释放资源
     */
    private static String url;
    private static String user;
    private static String password;
    private static String driver;
    /**
     * 文件读取，只需要读取一次即可拿到这些值，使用静态代码块
     */
    static {
        try {
            // 1. 创建 properties 集合类
            Properties properties = new Properties();
            // 2. 读取文件
            ClassLoader classLoader = JDBCUtil.class.getClassLoader();
            URL resource = classLoader.getResource("jdbc.properties");
            String path = resource.getPath();
            properties.load(new FileReader(path));
            // 3. 赋值
            url = properties.getProperty("url");
            user = properties.getProperty("user");
            password = properties.getProperty("password");
            driver = properties.getProperty("driver");
            // 4. 注册驱动
            try {
                Class.forName(driver);
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取链接
     * @return 连接对象
     */
    public static Connection getConnection(){
        Connection connection = null;
        try {
            connection = DriverManager.getConnection(url, user, password);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return connection;
    }

    /**
     * 释放资源
     * @param resultSet
     * @param statement
     * @param connection
     */
    public static void close(ResultSet resultSet, Statement statement, Connection connection){
        if(resultSet != null){
            try {
                resultSet.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(statement != null){
            try {
                statement.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(connection != null){
            try {
                connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

jdbc.properties

url=jdbc:mysql:///demo1026
user=zhang
password=1997
driver=com.mysql.jdbc.Driver