Use fileupload to process file uploads

Last Update:2018-12-07 Source: Internet

Author: User

Tags http file upload

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Use fileupload to process file uploads

Author: ◇ Liu Dong posting time: 15:52:43

Commons is open to Apache Source code A Java sub-project in the Organization. This project mainly involves some common modules in development, such as file upload, command line processing, database connection pool, and xml configuration file processing. These projects bring together the painstaking efforts of software engineers from all over the world, and their performance and stability have all stood the test of practical applications. Effective use of these projects will bring obvious effects to the development. Fileupload is a sub-project used to process HTTP file uploads. This article describes how to use fileupload to process the file information submitted to the server by the browser.

To enable the developer who first came into contact with fileupload to better understand the project, we will implement a simple file upload function, and introduce the development steps step by step, as well as detailedCode.

Environment preparation

1. Download and install TomcatArticle);

2. Download the jar package commons-fileupload-1.0-beta-1.jar for file upload and copy the file to the {$ Tomcat}/common/lib directory (where {$ Tomcat} is the tomcat installation directory );

3. because the fileupload sub-project also needs to use another project commons-beanutils, you must download beanutils and copy the extracted file commons-beanutils.jar to the {$ Tomcat}/common/lib directory.

Development file upload page

The file upload interface 1 is shown. To increase efficiency, we designed three file domains and uploaded three files at the same time.

Figure 1 file upload page

The HTML code of the page is as follows:

          
           
<HTML>

In the code, pay special attention to the black body. Make sure that the value of the form's enctype is multipart/form-data, so that the browser can correctly upload files.

Process uploaded file information

This document describes how to use commons-fileupload. To facilitate modification and debugging, a JSP file is used for processing the storage of uploaded files. We save all files uploaded by the browser in a specified directory and display the details of all uploaded files on the page. The result of saving the page is shown in figure 2.

Figure 2 save page

Let's take a look at the save. JSP code:

          
           
<%/*** Demonstrate File Upload Processing * @ author <a href = "mailto: winter.lau@163.com"> Winter Lau </a> * @ version $ ID: Save. JSP, v 1.00 2003/03/01 10:10:15 */%> <% @ page Language = "Java" contenttype = "text/html; charset = GBK "%> <% @ page import =" Java. util. * "%> <% @ page import =" Org. apache. commons. fileupload. * "%> <HTML>

Note the significance of some parameter values of the fileupload object in this file. The following code shows the three parameters sizemax, sizethreshold, and repositorypath:

          
           
Fileupload Fu = new fileupload (); // sets the size of the file to be uploaded. Unit: byte Fu. setsizemax (10000000); // maximum size that will be stored in memory? // Set up to only data that can be stored in the memory. Unit: byte Fu. setsizethreshold (4096); // set the data stored in the hard disk directory Fu once the file size exceeds the value of getsizethreshold. setrepositorypath ("c: \ Temp ");

The meanings of these three parameters are as follows:

Sizemax is used to set the maximum size of the uploaded file. Once the size of the uploaded file exceeds this value, a fileuploadexception is thrown, prompting that the file is too large;

Sizethreshold sets the buffer size in the memory. Once the file size exceeds this value,ProgramOther data is automatically stored in the directory specified by the repositorypath as a buffer. Setting the value of this parameter can ensure stable and efficient operation of the server;

Repositorypath specifies the buffer directory.

Precautions

According to the actual application results, this module can work stably and efficiently. The value of the sizethreshold parameter is crucial. If the setting is too large, it will occupy too much memory. If the setting is too small, the hard disk will be frequently used as a buffer to sacrifice performance. Therefore, this value must be set based on the size distribution of uploaded files. For example, if the size of most files is around kb, you can use kb as the value of this parameter. Of course, it is not appropriate to increase the size. The use of commons-fileupload to process HTTP File Upload is very small, but there are many things worth studying

This article is an English version of an article which is originally in the Chinese language on aliyun.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to info-contact@alibabacloud.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

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