今天在写一个form表单的时候，提交到后台之后发现使用request.getParameter()拿到的值全部为null
错误原因是这个form表单中有一个文件(图片)上传的项，form表单中有一个属性enctype="multipart/form-data"。
<form name="articleform" class="form-horizontal" action="${pageContext.request.contextPath}/list?method=updateArticle"
method="post" enctype="multipart/form-data">查了一下这个属性
此时用request是拿不到这个值的，因为这个表单是基于流的方式提交的。
此时需要导入下面三个依赖，此处我使用的maven方式引入
<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.3.2</version>
</dependency>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.4</version>
</dependency>
<dependency>
<groupId>commons-beanutils</groupId>
<artifactId>commons-beanutils</artifactId>
<version>1.8.0</version>
</dependency>具体的实现方式如下
private void updateArticle() throws ServletException, IOException{
Article article = new Article();
DiskFileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
List items = null;
try {
items = upload.parseRequest(request);
} catch (FileUploadException e) {
e.printStackTrace();
}
Iterator iter = items.iterator();
String picUrl = null;
while (iter.hasNext()) {
FileItem item = (FileItem) iter.next();
if(item.isFormField()){//判断是非文件上传
String value = item.getString("UTF-8");
//分枝结构匹配上传项
switch (item.getFieldName()) {
case "id":
String id = value;
article.setId(Integer.parseInt(id));
break;
case "picUrl":
picUrl = value;
article.setImage(picUrl);
break;
case "code":
String code = value;
ArticleType type = new ArticleType();
type.setCode(code);
article.setArticleType(type);
break;
case "titleStr":
String title = value;
article.setTitle(title);
break;
case "supplier":
String supplier = value;
article.setSupplier(supplier);
break;
case "locality":
String locality = value;
article.setLocality(locality);
break;
case "price":
String price = value;
article.setPrice(Double.parseDouble(price));
break;
case "storage":
String storage = value;
article.setStorage(Integer.parseInt(storage));
break;
case "description":
String description = value;
article.setDescription(description);
break;
}
}else{
//得到文件保存路径
String sysPath = request.getServletContext().getRealPath("/resources/images/article/");
//得到上传问价的文件名 test.jpg
String filename = item.getName();
if (null == filename || filename == "") {
filename = picUrl;
}
sysPath = sysPath + filename;
article.setImage(filename);
File saveFile = new File(sysPath);
try {
item.write(saveFile);
} catch (Exception e) {
e.printStackTrace();
}
}
}
shopService.updateArticle(article);
request.setAttribute("tip","修改商品成功");
showUpdate();
}这样就可以拿到form表单上传的数据了，并且完成上传文件