Explanation of java web file upload and download examples (cool file upload Technology)
1、 Course overview
In the development of web application system, file upload function is a very common function. Today, we will mainly talk about the technical implementation of file upload function in Java Web. With the rapid development of Internet technology, users have higher and higher requirements for website experience. There are also many innovations in the technology of file upload function, such as asynchronous file upload and drag and drop upload, Paste upload, upload progress monitoring, file thumbnail, large file breakpoint continuation, large file second transmission, etc.
Basic knowledge required for this course:
Understand the basic content of HTTP protocol
Basic IO stream operation technology
Servlet Basics
Basic knowledge of JavaScript / jQuery Technology
2、 Basis of file upload
For file upload, the browser submits the file to the server in the form of stream, and all stream data will be carried to the server with the HTTP request. Therefore, the format of the request content when uploading files should be able to basically understand.
File upload page:
HTTP request content:
3、 Java background uses servlet to receive files
It is troublesome to use servlet to obtain the input stream of uploaded files and then parse the request parameters, so the file upload component of Apache's open source tool common fileUpload is generally used in the background.
4、 Upload components using webuploader
At the front end of the file upload page, we can choose to use some easy-to-use upload components, such as Baidu's open source component webuploader, which can basically meet some daily functions of file upload, such as asynchronous file upload, drag and drop upload, paste upload, upload progress monitoring, file thumbnail, and even large file breakpoint continuation and large file second transmission.
Download webupload component
http://fex.baidu.com/webuploader/ Download webupload package from webupload official website