servlet 获取form表单值为空

ye-子殇 2013-05-25 01:05:52

jsp表单
<%@page contentType="text/html; charset=GB2312"%>
<html><body><font size=3>
<center>
<form action="getNumber" method=post>
商品编号：<input type="text" name=number>
<p>商品名称:<input type="text" name=name></p>
<p>商品起拍价:<input type="text" name=price></p>
<p>商品描述：<textArea name="content" rows="6" cols="20"></textArea></p>
<br/><input type="submit" value="提交">
</center>
</form></font></body></html>

servlet 获取值
package china.dalian;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

import bean.Upload;

@SuppressWarnings("serial")
public class Computer extends HttpServlet{

public void doPost(HttpServletRequest request,HttpServletResponse response)
throws ServletException,IOException{
response.setContentType("text/html;charset=GB2312");
Upload upload=new Upload();
request.setAttribute("upload", upload);
String number=request.getParameter("number");
System.out.print(number+"========================");
String name=request.getParameter("name");
String price=request.getParameter("price");
String content=request.getParameter("content");
if(number==null){
number=" ";
}
if(name==null){
name=" ";
}
if(price==null){
price=" ";
}
if(content==null){
content=" ";
}
upload.setNumber(number);
upload.setName(name);
upload.setPrice(price);
upload.setContent(content);
request.setAttribute("upload", upload);
request.getRequestDispatcher("show.jsp").forward(request, response);
}
public void doGet(HttpServletRequest request,HttpServletResponse response)
throws ServletException,IOException{
doPost(request, response);
}
}

show.jsp输出
<%@page contentType="text/html; charset=GB2312"%>
<%@page import="bean.Upload" %>
<html><body><center>
<% Upload upload=(Upload)request.getAttribute("upload"); %>
输入的数为：
<br>名字：<%=upload.getName() %>
<br/>编号：<%=upload.getNumber() %>
<br/>价格：<%=upload.getPrice() %>
<br/>内容：<%=upload.getContent() %>
</center></body></html>

最后输出是为空的。大家帮忙看下那里出错了。

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一叶飞舟 2013-05-28

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保证servlet中每个form值都能获取到；保证页面跳转前保存的实体不是空的。

长笛党希望 2013-05-28

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在servlet中设断点，逐行调试。

shuaiguo_18 2013-05-27

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Upload upload=new Upload(); request.setAttribute("upload", upload); String number=request.getParameter("number"); System.out.print(number+"====================== 这个出错了,将request.setAttribute("upload", upload);将request.setAttribute("upload", upload);放在后面

java_cyy 2013-05-27

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引用 7 楼 w304341736 的回复:

正解
引用 5 楼 whos2002110 的回复:
你这为空是指什么?? 是后台就无法从request中取出你想要的值,还是show.jsp没有输出. 先定位到问题,就容易解决了

oh_Maxy 2013-05-25

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如下修改： RequestDispatcher rd = request.getRequestDispatcher("show.jsp") request.setAttribute("upload", upload); rd.forward(request, response); 还不行就跟下代码，看看在Computer里，upload的操作的那些参数是否有问题。

此去天山--沧海于心 2013-05-25

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(1)name="name",name="price" 这些加上双引号（2）</form> </center>位置换一下 (3)request.setAttribute("upload", upload); 放在session中试试，request.getSession.setAttribute("upload", upload); (4)method="post"加上双引号希望对楼主会有帮助、、、、、、

w304341736 2013-05-25