六大质量属性——以“信息领域热词分析系统”为例可用性代码层面描述

public class DBUtil{
    public static String db_url="jdbc:mysql://localhost:3306/xinfang?useUnicode=true&characterEncoding=UTF-8&serverTimezone=GMT";
    public static String db_user="root";
    public static String db_password="password";
    
    public static Connection getConn() {
        Connection conn=null;
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            conn=DriverManager.getConnection(db_url, db_user, db_password);
            System.out.println("连接数据库成功");
        }catch(Exception e) {
            System.out.println("连接数据库失败");
            e.printStackTrace();
        }
        return conn;
    }
    public static void close(Connection conn) {
        if(conn!=null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
    public static void close(Statement state,Connection conn) {
        if(state!=null) {
            try {
                state.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(conn!=null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
    
    public static void close(ResultSet rs, Statement state, Connection conn) {
        if(rs!=null) {
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(state!=null) {
            try {
                state.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(conn!=null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}