为什么使用preparedStatement就使用异常

显示全部楼层 · 2009-4-18 22:47:43

exception
javax.servlet.ServletException: ??????
org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:867)
org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:800)
org.apache.jsp.usersLogin_005fdo_jsp._jspService(usersLogin_005fdo_jsp.java:54)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:133)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:311)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
root cause
java.lang.Exception: ??????
dzzw.hpj.dao.impl.UsersDaoImpl.delete(UsersDaoImpl.java:140)
org.apache.jsp.usersLogin_005fdo_jsp._jspService(usersLogin_005fdo_jsp.java:47)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:133)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:311)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
我调用的是delete函数咯没传入中文这是我的代码

还有我UsersDaoImpl中的delete方法
--------------------------------------------
public void delete(String countId) throws Exception
{
String sql="DELETE FROMusers WHERE countId=? " ;
ConnectionDB conn=null;
PreparedStatement pstmt=null;
try
{
conn=new ConnectionDB();
pstmt=conn.getConnection().prepareStatement(sql);
pstmt.setString(1,countId);
pstmt.executeUpdate();
pstmt.close();
}
catch (Exception e)
{
throw new Exception("删除出现异常");
}
finally
{
conn.close();
}
}
提示错误是java.lang.NullPointerException
at dzzw.hpj.dao.impl.UsersDaoImpl.delete(UsersDaoImpl.java:134)134行的代码是pstmt=conn.getConnection().prepareStatement(sql);

千问 · 2009-4-18 22:47:43

问题不出现在preparedStatement这里，而是出在你传入的参数问题。建议你将传入参数打印一下，你就可以看出来，至于乱码问题，我想上网搜到的肯定比我说的要详细。谢谢...

千问 · 2009-4-18 22:47:43

我觉得可能是填入参数类型问题.WHERE countId=?countid是整型吧 pstmt.setInt(1,Integer.praseInt(countId));如果不是,看看部署的应用下面 usersLogin_005fdo_jsp._jspService这个文件的抛错行数,看看是哪句代码的错误....

千问 · 2009-4-18 22:47:43

可以在catch中打印以下异常的具体信息catch (Exception e) { e.printStackTrace();throw new Exception("删除出现异常"); } 看一下控制台的异常信息，处理起来会有头绪...

千问 · 2009-4-18 22:47:43

你的delete 方法抛出了异常，但是在jsp页面没有catch。加个try试试。...

千问 · 2009-4-18 22:47:43

给出的代码有点少...