使用 request.getParameter("id"); 時要特別注意不要隨意在相應鏈接URL中添加空格,例如:
str += "<tr><td>" + rs.getInt("id") + "</td><td>" + prestr +
"<a href = 'showArticleDetails.jsp?id=" + rs.getInt("id") + "'>" + rs.getString("title") + "</a>" + "</td></tr>";
"<a href = 'showArticleDetails.jsp?id = " + rs.getInt("id") + "'>"
就會報錯:java.lang.NumberFormatException: null,因爲傳遞進去的是空格而非數值。