<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>添加图书的提交界面</title>
</head>
<body>
<form action="insert_book.jsp" method="post" >
<table>
<tr>
<td>图书号</td>
<td><input type="text" ,name="num"></td>
</tr>
<tr>
<td>图书名</td>
<td><input type="text" ,name="title"></td>
</tr>
<tr>
<td>作者名</td>
<td><input type="text" ,name="author"></td>
</tr>
<tr>
<td>价格</td>
<td><input type="text" ,name="price"></td>
</tr>
<tr>
<td>备注</td>
<td><input type="text" ,name="remarks"></td>
</tr>
<tr align="center">
<td colspan="2"><input type="submit" ,value="提 交">
<input type="reset" ,value="取 消"></td>
</tr>
</table>
</form>
</body>
</html>在运行这段代码时，我想把获取的num,title等参数传递到insert_book.jsp中，结果发现传递值一直是null，导致我发送给数据库中的参数也是null
String sql="insert into book(num,title,author,price,remarks)values(?,?,?,?,?)";
System.out.println(sql);
PreparedStatement pstmt=conn.prepareStatement(sql);
request.setCharacterEncoding("UTF-8");
String num=request.getParameter("num");
String title=request.getParameter("title");
String author=request.getParameter("author");
String price=request.getParameter("price");
String remarks=request.getParameter("remarks");
pstmt.setString(1,num);
pstmt.setString(2,title);
pstmt.setString(3,author);
pstmt.setString(4,price);
pstmt.setString(5,remarks);
int n=pstmt.executeUpdate();
if(n==1){%>数据插入操作成功！<br><%}
else{%>数据插入操作失败！<br><%
}
if(pstmt!=null)
pstmt.close();
if(conn!=null)
conn.close();
%>
<td><input type="text" ,name="num"></td>
name 前面的逗号去掉
<td><input type="text" name="num"></td>