Jsp 代码执行后的java.lang.NullPointerException
在我将数据输入表格并提交后,我有这两页,它写道: 扎罗ženíletadlaJsp 代码执行后的java.lang.NullPointerException,jsp,Jsp,在我将数据输入表格并提交后,我有这两页,它写道: 扎罗ženíletadla java.lang.NullPointerException 我该怎么处理这个问题呢……因为用户编写的可以谷歌搜索的手册对我没有帮助:( admin.jsp: 扎洛伊特莱塔德罗 身份证件: letadla型号: 波切特赛德尔: 和vlozit.php 行政竞赛 扎罗ženíletadla 在调用连接对象上的方法之前,应该检查该连接对象是否为null Connection conn = DriverManage
java.lang.NullPointerException 我该怎么处理这个问题呢……因为用户编写的可以谷歌搜索的手册对我没有帮助:( admin.jsp:
扎洛伊特莱塔德罗
身份证件:
letadla型号:
波切特赛德尔:
和vlozit.php
行政竞赛
扎罗ženíletadla
在调用连接对象上的方法之前,应该检查该连接对象是否为null
Connection conn = DriverManager.getConnection("jdbc:odbc:ATBS", "CENTOS", "Shaman123");
if(conn != null)
{
Statement statement = conn.createStatement();
String command = "INSERT INTO letadlo (ID, model, sedadel) VALUES ('"+ID+"', '"+model+"', '"+sedadel+"')";
PreparedStatement ps = conn.prepareStatement(command);
ps.execute();
conn.close(); //Ideally it should be closed inside finally.
}
理想情况下,
Connection
和PrepareStatement
应该在finally
块中关闭。请显示stacktraceException Stacktrace?我是jsp初学者…如何显示Stacktrace?使用if(conn!=null)尝试了您的想法,但仍然是java.lang.NullPointerException:(为什么要同时创建PreparedStatement和Statement。我认为不需要Statement。
<%@ page import="java.sql.*" %>
<%@ page import="java.io.*" %>
<%@ page import="java.util.*" %>
<HTML>
<HEAD>
<TITLE>Administrace</TITLE>
</HEAD>
<BODY>
<H1>Založení letadla</H1>
<%
String ID= request.getParameter("id");
String model = request.getParameter("model");
String sedadel = request.getParameter("sedadel");
try{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection conn = DriverManager.getConnection("jdbc:odbc:ATBS", "CENTOS", "Shaman123");
if(conn != null){
Statement statement = conn.createStatement();
String command = "INSERT INTO letadlo (ID, model, sedadel) VALUES ('"+ID+"', '"+model+"', '"+sedadel+"')";
PreparedStatement ps = conn.prepareStatement(command);
if(ps != null){
ps.execute();}}
conn.close();
}
catch(Exception e)
{
out.println(e);
}
%>
</BODY>
Connection conn = DriverManager.getConnection("jdbc:odbc:ATBS", "CENTOS", "Shaman123");
if(conn != null)
{
Statement statement = conn.createStatement();
String command = "INSERT INTO letadlo (ID, model, sedadel) VALUES ('"+ID+"', '"+model+"', '"+sedadel+"')";
PreparedStatement ps = conn.prepareStatement(command);
ps.execute();
conn.close(); //Ideally it should be closed inside finally.
}