如何检索上传的图像并保存到JSP文件？ [英] How to retrieve uploaded image and save to a file with JSP?

问题描述

如何检索上传的图片并保存到jsp文件？

创建一个web项目

创建一个至少包含以下内容：

 < form action =uploadmethod =postenctype =multipart / form-data> ; 
< input type =filename =file> 
< input type =submit> 
< / form> 
  

转至 Apache Commons FileUpload主页，阅读 用户指南和常见问题部分。 / b>

下载以下库的二进制文件：

• commons-fileupload


• commons-io

>
解压缩zip文件，并将JAR文件放在您的web项目的 / WEB-INF / lib 中。

创建一个至少包含以下内容的Servlet类：

  publi c类UploadServlet扩展HttpServlet {
 @Override $ b $保护无效doPost（HttpServletRequest请求，HttpServletResponse响应）抛出ServletException异常IOException {
 List< FileItem> items = null; 
尝试{
 items = new ServletFileUpload（new DiskFileItemFactory（））。parseRequest（request）; 
 catch（FileUploadException e）{
 throw new ServletException（Can not parse multipart request。，e）; （FileItem item：items）{
 if（item.isFormField（））{
 //这里处理常规表单字段的方式与request.getParameter（） 。 
 //您可以通过item.getFieldName（）获取参数名称; 
 //你可以通过item.getString（）获取参数值; 
} else {
 //在这里处理上传的字段。 
 String filename = FilenameUtils.getName（item.getName（））; //获取文件名。 
 File file = new File（/ path / to / uploads，filename）; //定义目标文件
 item.write（file）; //写入目标文件
} 
} 
 //显示结果页面。 
 request.getRequestDispatcher（result.jsp）。forward（request，response）; 
 
 
 
 $ b $  
将web.xml中的servlet映射为如下：
 
 
 < servlet> 
< servlet-name>上传< / servlet-name> 
< servlet-class> mypackage.UploadServlet< / servlet-class> 
< / servlet> 
< servlet-mapping> 
< servlet-name>上传< / servlet-name> 
< url-pattern> / upload< / url-pattern> 
< / servlet-mapping> 
  
 

就是这样。在JSP中提交表单时，它将调用与< url-pattern> / upload >的servlet，然后servlet将在 doPost（）方法中完成它的任务。最后，这一切都很简单。希望这有助于。

Sorry but I'm totally new to jsp.

How to retrieve uploaded image and save to a file with jsp?

解决方案

1. Create a web project.

2. Create a JSP file with at least the following content:

   <form action="upload" method="post" enctype="multipart/form-data">
       <input type="file" name="file">
       <input type="submit">
   </form>
   

3. Go to Apache Commons FileUpload homepage, read both the User Guide and Frequently Asked Questions sections.

4. Download the binaries of the following libraries:

   • commons-fileupload
   • commons-io

5. Unpack the zips and place the JAR files in the /WEB-INF/lib of your web project.

6. Create a Servlet class with at least the following content:

   public class UploadServlet extends HttpServlet {
       @Override
       protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           List<FileItem> items = null;
           try {
               items = new ServletFileUpload(new DiskFileItemFactory()).parseRequest(request);
           } catch (FileUploadException e) {
               throw new ServletException("Cannot parse multipart request.", e);
           }
           for (FileItem item : items) {
               if (item.isFormField()) {
                   // Process regular form fields here the same way as request.getParameter().
                   // You can get parameter name by item.getFieldName();
                   // You can get parameter value by item.getString();
               } else {
                   // Process uploaded fields here.
                   String filename = FilenameUtils.getName(item.getName()); // Get filename.
                   File file = new File("/path/to/uploads", filename); // Define destination file.
                   item.write(file); // Write to destination file.
               }
           }
           // Show result page.
           request.getRequestDispatcher("result.jsp").forward(request, response);
       }
   }
   

7. Map the servlet in web.xml as follows:

   <servlet>
       <servlet-name>upload</servlet-name>
       <servlet-class>mypackage.UploadServlet</servlet-class>
   </servlet>
   <servlet-mapping>
       <servlet-name>upload</servlet-name>
       <url-pattern>/upload</url-pattern>
   </servlet-mapping>
   

That should be it. When you submit the form in the JSP, it will invoke the action /upload which matches the <url-pattern> of the servlet and then the servlet will do its task in the doPost() method. At end it's all fairly simple. Hope this helps.

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