JavaWeb-使用fileload组件

谁践踏了优雅 2023-08-17 17:41 100阅读 0赞

**①搭建环境**

**　　**commons-fileupload.jar

commons-io.jar

<dependency>
          <groupId>commons-fileupload</groupId>
          <artifactId>commons-fileupload</artifactId>
          <version>1.3.1</version>
        </dependency>
    
        
        <dependency>
          <groupId>commons-io</groupId>
          <artifactId>commons-io</artifactId>
          <version>2.4</version>
        </dependency>

**②基本思想**

**　　**> commons-fileupload可以解析请求，得到一个FileItem对象组成的List

> commons-fileupload把所有的请求信息都解析为FileItem对象。无论是一个一般的文本域还是一个文件域。

> 可以调用FileItem的isFormField()方法来判断是一个表单域或不是表单域(则是一个文件域)

> 再来进一步获取信息

if(item.isFormField())\{

String name = item.getFieldName();

String value = item.getString();

...

if(!item.isFormField())\{

String fieldName = item.getFieldName();

String fileName = item.getName();

String contentType = item.getContentType();

boolean isTnMemory = item.isInMemory();

long sizeInBytes = items.getSize();

InputStream uploadedStream = item.getInputStream();

...

uploadedStream.close();

**③如何得到List<FileItem>对象**

**　　**> 简单的方式

//Create a factory for disk-based file items

FileItemFactory factory = new DiskFileItemFactory();

//Create a new file upload handler

ServletFileUpload upload = new ServletFileUpload(factory);

//Parse the request

List /\* FileItem \*/ items = upload.parseRequest(request);

> 复杂的方式：可以为文件的上传加入一些限制条件和其他的属性

//Create a factory for disk-based file items

DiskFileItemFactory factory = new DiskFileItemFactory();

//设置内存中最多可以存放的上传文件的大小，若超出则把文件写到一个临时文件夹中，以byte为单位

factory.setSizeThreshold(yourTempDirectory);

//设置临时文件夹

factory.setRepository(yourTempDirectory);

//create a new file upload handler

ServletFileUpload upload = new ServletFileUpload(factory);

//设置上传文件的总的大小，也可以设置单个文件的大小

upload.setSizeMax(yourMaxRequestSize);

//Parse the request

List /\* FileItem \*/ items = upload.parseRequest(request);

Servlet:

public class UploadServlet extends HttpServlet {
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            //1.得到FileItem的集合items
            //Create a factory for disk-based file items
    
        DiskFileItemFactory factory = new DiskFileItemFactory();
    
        //设置内存中最多可以存放的上传文件的大小，若超出则把文件写到一个临时文件夹中，以byte为单位
    
        factory.setSizeThreshold(1024 * 500);
    
        //设置临时文件夹
            File yourTempDirectory = new File("d:\\tempDirectory");
    
    
        factory.setRepository(yourTempDirectory);
    
        //create a new file upload handler
    
        ServletFileUpload upload = new ServletFileUpload(factory);
    
        //设置上传文件的总的大小，也可以设置单个文件的大小
    
        upload.setSizeMax(1024 * 1024 * 5);
    
        //Parse the request
    
            try {
                List<FileItem> /* FileItem */ items = upload.parseRequest(req);
    
                //2.遍历items
                for (FileItem item :items
                     ) {
    //                若是一个一般额表单域，打印信息
                    if (item.isFormField()){
                        String name = item.getFieldName();
                        String value = item.getString();
    
                        System.out.println(name + ":    " + value);
                    }
    //                若是文件域则把文件保存到d:\\files目录下
                    else {
                        String fieldName = item.getFieldName();
                        String fileName = item.getName();
                        String contentType = item.getContentType();
                        long sizeInBytes = item.getSize();
    
                        System.out.println(fieldName);
                        System.out.println(fileName);
                        System.out.println(contentType);
                        System.out.println(sizeInBytes);
    
                        InputStream is = item.getInputStream();
                        byte [] buffer = new byte[1024];
                        int len = 0;
                        fileName = "d:\\files\\" + fieldName;
                        OutputStream out = new FileOutputStream(fileName);
    
                        while ((len = is.read(buffer))!= -1){
                            out.write(buffer,0,len);
                        }
                        is.close();
                        out.close();
                    }
                }
            } catch (FileUploadException e) {
                e.printStackTrace();
            }
        }
    }

jsp

效果：

![1642540-20190722094925969-942887936.png][]

![1642540-20190722094935257-860919803.png][]

转载于:https://www.cnblogs.com/yangHS/p/11224097.html

[1642540-20190722094925969-942887936.png]: /images/20230808/8a73d3b509a646de82c14c36dd0ba564.png
[1642540-20190722094935257-860919803.png]: /images/20230808/9829d93302764d6fbe80e6fc7a750baf.png