実現したいこと
https://www.javadrive.jp/servlet/schedule/index10.html
上記サイトのプログラムを作っています
発生している問題・分からないこと
できたページに飛ぼうとすると例外が出てしまいます
エラーメッセージ
error
1Cannot invoke "java.sql.Connection.prepareStatement(String)" because "this.conn" is null
該当のソースコード
import java.io.*; import jakarta.servlet.*; import jakarta.servlet.http.*; import java.sql.*; public class ScheduleInsert1 extends HttpServlet{ public void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException{ req.setCharacterEncoding("Shift-JIS"); res.setContentType("text/html;charset=Shift_Jis"); PrintWriter out = res.getWriter(); int year; int month; int day; int shour; int sminute; int ehour; int eminute; String plan; String memo; String param = req.getParameter("YEAR"); if (param == null || param.length() == 0){ year = -999; }else{ try{ year = Integer.parseInt(param); }catch (NumberFormatException e){ year = -999; } } param = req.getParameter("MONTH"); if (param == null || param.length() == 0){ month = -999; }else{ try{ month = Integer.parseInt(param); }catch (NumberFormatException e){ month = -999; } } param = req.getParameter("DAY"); if (param == null || param.length() == 0){ day = -999; }else{ try{ day = Integer.parseInt(param); }catch (NumberFormatException e){ day = -999; } } param = req.getParameter("SHOUR"); if (param == null || param.length() == 0){ shour = -999; }else{ try{ shour = Integer.parseInt(param); }catch (NumberFormatException e){ shour = -999; } } param = req.getParameter("SMINUTE"); if (param == null || param.length() == 0){ sminute = -999; }else{ try{ sminute = Integer.parseInt(param); }catch (NumberFormatException e){ sminute = -999; } } param = req.getParameter("EHOUR"); if (param == null || param.length() == 0){ ehour = -999; }else{ try{ ehour = Integer.parseInt(param); }catch (NumberFormatException e){ ehour = -999; } } param = req.getParameter("EMINUTE"); if (param == null || param.length() == 0){ eminute = -999; }else{ try{ eminute = Integer.parseInt(param); }catch (NumberFormatException e){ eminute = -999; } } param = req.getParameter("PLAN"); if (param == null || param.length() == 0){ plan = ""; }else{ try{ plan = param; }catch (NumberFormatException e){ plan = ""; } } param = req.getParameter("MEMO"); if (param == null || param.length() == 0){ memo = ""; }else{ try{ memo = param; }catch (NumberFormatException e){ memo = ""; } } /* 日付が不正な値で来た場合はパラメータ無しで「MonthView」へリダイレクトする */ if (year == -999 || month == -999 || day == -999){ res.sendRedirect("/schedule/MonthView"); } String dateStr = year + "-" + month + "-" + day; String startTimeStr = shour + ":" + sminute + ":00"; String endTimeStr = ehour + ":" + eminute + ":00"; /* 日付が指定されていない場合は、開始及び終了時刻をNULLとして登録する */ if (shour == -999 || sminute == -999 || ehour == -999 || eminute == -999){ startTimeStr = null; endTimeStr = null; } Connection conn = null; String url = "jdbc:mysql://localhost/svschedule"; String user = "(username)"; String password = "(passward)"; try { Class.forName("com.mysql.jdbc.Driver").newInstance(); conn = DriverManager.getConnection(url, user, password); String sql = "insert into schedule (userid, scheduledate, starttime, endtime, schedule, schedulememo) values (?, ?, ?, ?, ?, ?)"; PreparedStatement pstmt = conn.prepareStatement(sql); pstmt.setInt(1, 1); pstmt.setString(2, dateStr); pstmt.setString(3, startTimeStr); pstmt.setString(4, endTimeStr); pstmt.setString(5, plan); pstmt.setString(6, memo); int num = pstmt.executeUpdate(); pstmt.close(); }catch (ClassNotFoundException e){ out.println("ClassNotFoundException:" + e.getMessage()); }catch (SQLException e){ out.println("SQLException:" + e.getMessage()); }catch (Exception e){ out.println("Exception:" + e.getMessage()); }finally{ try{ if (conn != null){ conn.close(); } }catch (SQLException e){ out.println("SQLException:" + e.getMessage()); } } StringBuffer sb = new StringBuffer(); sb.append("/schedule/MonthView"); sb.append("?YEAR="); sb.append(year); sb.append("&MONTH="); sb.append(month - 1); res.sendRedirect(new String(sb)); } }
試したこと・調べたこと
上記の詳細・結果
同様の質問があったが解決方法がわからなかった
補足
特になし
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