JDBC封装

public class JDBCUtil {
    private static  String driver = "com.mysql.jdbc.Driver";
    private static  String url = "jdbc:mysql://localhost:3306/?day14/useUnicode=true&characterEncoding=utf-8";
    private static  String username = "root";
    private static  String password = "admin";

    private static  Connection conn =null;
    private static  PreparedStatement statement = null;
    private static  ResultSet result = null;



    /**
     * 加载配置文件
     * 获取数据库连接
     * @return
     */
    static{
        try {
            Properties properties = new Properties();
            //通过类加载器 加载配置文件
            properties.load(JDBCUtil.class.getClassLoader().getResourceAsStream("jdbc.properties"));

            driver = properties.getProperty("jdbc.driver");
            url = properties.getProperty("jdbc.url");
            username = properties.getProperty("jdbc.username");
            password = properties.getProperty("jdbc.password");

            //加载驱动
            Class.forName(driver);
        }catch (IOException e){
            e.printStackTrace();
        }catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取连接
     * @return
     */
    public static Connection getConnection(){
        try {
            conn = DriverManager.getConnection(url,username,password);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return conn;
    }

    /**
     * 获取操作数据库对象
     * @param sql
     * @param objects
     * @return
     */
    public static PreparedStatement getStatement(String sql,Object...objects){
        //加载驱动
        try {
            //创建执行对象
            statement = conn.prepareStatement(sql);
            //如果有参数  则添加参数
            if (objects.length > 0){
                for (int i=0;i<objects.length;i++){
                    statement.setObject(i+1,objects[i]);
                }
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return statement;
    }

    /**
     * 查询
     * 返回查询结果集
     * @param sql 语句
     * @param objects 可变参数
     * @return ResultSet 结果集合
     */
    public static ResultSet executeQuery(String sql,Object...objects){
        statement = getStatement(sql,objects);
        try {
            result = statement.executeQuery();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return result;
    }

    /**
     * 对数据库的增,删,改
     * @param sql 语句
     * @param objects 可变参数
     * @return 操作完成的sql语句数量
     */
    public static int executeUpdate(String sql,Object...objects){
        statement = getStatement(sql,objects);
        //执行成功的条数
        int count = 0;
        try {
            count = statement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return count;
    }

    /**
     * 关闭连接 释放资源
     */
    public static void closeAll(){
        try{
            if (result != null){
                result.close();
            }
            if (statement != null){
                statement.close();
            }
            if (conn != null){
                conn.close();
            }
        }catch(Exception e){
            e.printStackTrace();
        }
    }
}