java JSP多部分请求时获取参数
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Get parameter when multipart request in JSP
提问by alaa joma
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Add new product</title>
<link type="text/css" rel="Stylesheet" href="css/SiteStyle.css" />
<script src="js/jquery-1.3.2.js" type="text/javascript"></script>
</head>
<body>
<form id="MainForm" action="Relay" method="post" enctype="multipart/form-data">
<input name="destination" type="hidden" value="AddNewProduct" />
<script src="js/AddNewProduct.js" type="text/javascript"></script>
<center>
<h1>Add new product</h1>
<hr />
<table class="TableLogin">
<tr>
<td align="center" colspan="2" class="TDLoginHeader">
Product information</td>
</tr>
<tr>
<td align="right" class="TDLoginTitle">
Product Title
</td>
<td align="left" class="TDLoginText">
<input id="TxtTitle" type="text" class="LoginTextBoxes" name="Title" maxlength="75" /></td>
</tr>
<tr>
<td align="right" class="TDLoginTitle">
Dollar price
</td>
<td align="left" class="TDLoginText">
<input id="TxtPrice" type="text" class="LoginTextBoxes" name="Price" maxlength="15" /></td>
</tr>
<tr>
<td align="center" colspan="2" class="TDLoginTitle">
Product number</td>
</tr>
<tr>
<td align="center" colspan="2">
<table style="width:100%;">
<tr>
<td align='center' class='TDProductNumber'>
<input id='Txtdigit1' name='Txtdigit1' class='TxtProductNumber' type='text' />
</td>
<td align='center' class='TDProductNumber'>
<input id='Txtdigit2' name='Txtdigit2' class='TxtProductNumber' type='text' />
</td>
<td align='center' class='TDProductNumber'>
<input id='Txtdigit3' name='Txtdigit3' class='TxtProductNumber' type='text' />
</td>
<td align='center' class='TDProductNumber'>
<input id='Txtdigit4' name='Txtdigit4' class='TxtProductNumber' type='text' />
</td>
<td align='center' class='TDProductNumber'>
<input id='Txtdigit5' name='Txtdigit5' class='TxtProductNumber' type='text' />
</td>
<td align='center' class='TDProductNumber'>
<input id='Txtdigi6' name='Txtdigit6' class='TxtProductNumber' type='text' />
</td>
<td align='center' class='TDProductNumber'>
<input id='Txtdigit7' name='Txtdigit7' class='TxtProductNumber' type='text' />
</td>
</tr>
<tr>
<td colspan="7" class="TDLoginTitle">
<label>Product Image</label>
<input id="ProductImage" name="ProductImage" type="file" />
</td>
</tr>
</table>
</td>
</tr>
<tr>
<td align="center" colspan="2">
<input id="BtnAdd" type="button" value="Add" class="BtnSize" /></td>
</tr>
</table>
<div id="DivAddMessage">
</div>
<div>
<a href='Login.jsp'>Back</a>
</div>
</center>
</form>
</body>
</html>
Servlet 'Relay' code:
Servlet“中继”代码：
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
String destination=request.getParameter("destination");
out.print(destination);
}
this is a piece of code for enter product inforamtion (title , price , 7 digit number, product image) , when i want to get 'destination' parameter in servlet the value got is null i know that because multipart request , but how i can get this value and the file uploaded value ?
这是一段用于输入产品信息（标题、价格、7 位数字、产品图片）的代码，当我想在 servlet 中获取“目标”参数时，得到的值为 null 我知道这是因为多部分请求，但我怎么能获取此值和文件上传值？
回答by Sathish
Since you post using multipart encoding ('multipart/form-data') the parameters are not present as you expect.
由于您使用多部分编码 ('multipart/form-data') 进行发布，因此参数并不如您所愿。
If for instance you are using commons-fileuploadthe parameters would be present as and are identifiable using the 'isFormField' method on the FileItem object.
例如，如果您使用的是commons-fileupload，则参数将显示为并且可以使用 FileItem 对象上的“isFormField”方法进行识别。
This thead on coderanch explains how: coderanch
coderanch 上的这个标题解释了如何：coderanch
Most (every) modern webframeworks abstract this away and make this sort of stuff much easier by the way. Refer this site it will help you
大多数（每一个）现代网络框架都将其抽象出来，顺便让这类东西变得更容易。 参考这个网站它会帮助你
CODE
代码
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
try {
List<FileItem> items = new ServletFileUpload(new DiskFileItemFactory()).parseRequest(request);
for (FileItem item : items) {
if (item.isFormField()) {
// Process regular form field (input type="text|radio|checkbox|etc", select, etc).
String fieldname = item.getFieldName();
String fieldvalue = item.getString();
// ... (do your job here)
} else {
// Process form file field (input type="file").
String fieldname = item.getFieldName();
String filename = FilenameUtils.getName(item.getName());
InputStream filecontent = item.getInputStream();
// ... (do your job here)
}
}
} catch (FileUploadException e) {
throw new ServletException("Cannot parse multipart request.", e);
}
// ...
}
回答by laksys
use Annotation
使用注解
@MultipartConfig
@MultipartConfig
for your Servlet
为您的 Servlet
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