qq_43764144 2019-05-31 16:50 采纳率: 43.5%
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写了一个jsp文件出现报错

严重: Servlet.service() for servlet jsp threw exception
java.lang.NullPointerException
    at org.apache.jsp.inputCheck_jsp._jspService(inputCheck_jsp.java:76)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:261)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:581)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
    at java.lang.Thread.run(Thread.java:619)

jsp代码

<%@page import="java.sql.*"%>
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>数据更新后的页面</title>
  </head>

  <body>
    <center>
        <h3>已添加学生信息</h3>
        <hr>
        <%
            String studentNumber=request.getParameter("studentNumber");
            byte b []=studentNumber.getBytes("ISO-8859-1");
            studentNumber=new String(b,"UTF-8");

            String studentName=request.getParameter("studentName");
            byte b1 []=studentName.getBytes("ISO-8859-1");
            studentName=new String(b1,"UTF-8");

            String studentSex=request.getParameter("studentSex");
            byte b2 []=studentSex.getBytes("ISO-8859-1");
            studentSex=new String(b2,"UTF-8");

            String studentAge=request.getParameter("studentAge");
            byte b3 []=studentAge.getBytes("ISO-8859-1");
            studentAge=new String(b3,"UTF-8");

            String studentWeight=request.getParameter("studentWeight");
            byte b4 []=studentWeight.getBytes("ISO-8859-1");
            studentWeight=new String(b4,"UTF-8");

            Class.forName("com.mysql.jdbc.Driver");
            String url="jdbc:mysql://localhost:3333/pubs?useUnicode=true&characterEncoding=gbk";
            Connection conn=DriverManager.getConnection(url,"root","123456");
            Statement stmt=conn.createStatement();
            String sql="insert into info values('"+studentNumber+"','"+studentName+"','"+studentSex+"',"+studentAge+","+studentWeight+")";
            stmt.executeUpdate(sql);
            stmt.close();
            conn.close();   
         %>


         <h3>已更改学生信息</h3>
         <hr>
         <%
            Class.forName("com.mysql.jdbc.Driver");
            String url1="jdbc:mysql://localhost:3333/pubs?useUnicode=true&characterEncoding=gbk";
            Connection conn1=DriverManager.getConnection(url1,"root","123456");
            Statement stmt1=conn1.createStatement();
            String sql1="update info set studentAge=18";
            stmt1.executeUpdate(sql1);
            stmt1.close();
            conn1.close();
          %>
          <h3>已删除学生信息</h3>
          <hr>
          <%
            Class.forName("com.mysql.jdbc.Driver");
            String url2="jdbc:mysql://localhost:3333/pubs?useUnicode=true&characterEncoding=gbk";
            Connection conn2=DriverManager.getConnection(url1,"root","123456");
            Statement stmt2=conn2.createStatement();
            String sql2="delete from info where studentSex='男'";
            stmt2.executeUpdate(sql2);
            stmt2.close();
            conn2.close();
           %>
          <h3>经过以上操作后,数据库中有以下记录</h3>
            <hr>
          <table border=2 bgcolor="ccceee" align="center">
            <tr>
                <td>学号</td>
                <td>姓名</td>
                <td>性别</td>
                <td>年龄</td>
                <td>体重</td>
            </tr>
          <%
            Class.forName("com.mysql.jdbc.Driver");
            String url3="jdbc:mysql://localhost:3333/pubs?useUnicode=true&characterEncoding=gbk";
            Connection conn3=DriverManager.getConnection(url3,"root","123456");
            Statement stmt3=conn3.createStatement();
            String sql3="select * from info";
            ResultSet rs=stmt3.executeQuery(sql3);
            while(rs.next()){
           %>
            <tr>
                <td><%=rs.getString("studentNumber") %></td>
                <td><%=rs.getString("studentName") %></td>
                <td><%=rs.getString("studentSex") %></td>
                <td><%=rs.getString("studentAge") %></td>
                <td><%=rs.getString("studentWeight") %></td>
            </tr>
           <%}
                rs.close();
                stmt3.close();
                conn3.close();
            %>
          </table>
        <hr>    
   </center>
  </body>
</html>
  • 写回答

1条回答 默认 最新

  • 专家-郭老师 Java领域新星创作者 2019-05-31 17:05
    关注

    空指针异常了。看报错提示 你的inputCheck_jsp.java:76 这个页面报错, 第76行。看看那个76代码,数据没有获取到

    评论

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