Difference between Struts2 FilterDispatcher and StrutsPrepareAndExecuteFilter?

Posted by Mohaideen Jamil in Struts-2

 
The FilterDispatcher is used in the early Struts2 development, and it has deprecated since Struts 2.1.3.
 
** UPDATE: Struts 2 Complete tutorial now available here.
 
If you are using Struts version >= 2.1.3, it’s recommended to upgrade the new filter class StrutsPrepareAndExecuteFilter
 
The new filter was introduced for the following reasons

1. There were a lot of issued with the FilterDispatcher and its deployment.
2. New Filter provides a better way to enable customizations and overrides.
3. Make it crystal clear to developers what filters are doing what processes.
4. make dispatch process be more flexible to support things like native operation in OSGi or plugin system.

 
For your reference, the following code should be used when you are about to use Struts version <=2.1.3

1. FilterDispatcher example

...
<filter>
   <filter-name>struts2</filter-name>
   <filter-class>
     org.apache.struts2.dispatcher.FilterDispatcher
   </filter-class>
</filter>
...

 
The following code should be used when you are about to use Struts version >=2.1.3

2. StrutsPrepareAndExecuteFilter example

...
<filter>
<filter-name>struts2</filter-name>
<filter-class>
org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter
</filter-class>
</filter>
...

File Upload Example in Struts 2

Posted by Mohaideen Jamil in Struts 2 Tutorial, Struts-2 | 2 comments

 
In Struts 2 file uploading can done with the help of built-in FileUploadInterceptor. We use <s:file> tag to create a file upload component, which allow users to select file from their local disk and upload it to the server. The encoding type of the form should be set to multipart/form-data and the HTTP method should be set to post. The Struts 2 File Upload Interceptor is based on MultiPartRequestWrapper, which is automatically applied to the request if it contains the file element. Then it adds the following parameters to the request
 
** UPDATE: Struts 2 Complete tutorial now available here.
 
(assuming the uploaded file name is uploadDoc).

• [uploadDoc]File – Will store the actual uploaded File
• [uploadDoc]ContentType : This String will store the content type of the file
• [uploadDoc]FileName : This String will store the actual name of the uploaded file (not the HTML name)

In the action class you can get the file, the uploaded file name and content type by just creating getter and setters.
 
For example

private File uploadDoc;

This will store actual uploaded File

private String uploadDocFileName;

This string will contain the file name of uploaded file.

private String uploadDocContentType;

This string will contain the Content Type of uploaded file.
 
The file upload interceptor also does the validation and adds errors. These error messages are stored in the struts-messsages.properties file. The values of the messages can be overridden by providing the text for the following keys:
 

Parameters

 
You can use the following parameters to control the file upload functionality.

• maximumSize This parameter is optional. The default value of this is 2MB.

 <param name="maximumSize">1024000</param>

<constant name="struts.multipart.maxSize" value="20097152" />

• allowedTypes This parameter is also optional. It allows you to specify the allowed content type.

<param name="allowedTypes"> text/plain </param>

<param name="allowedTypes"> application/pdf</param>

Folder Structure

Action class

 
FileUploadAction.java
 

package com.simplecode.action;

import java.io.File;
import com.opensymphony.xwork2.ActionSupport;

public class FileUploadAction extends ActionSupport {

	private static final long serialVersionUID = 1L;
	private File uploadDoc;
	private String uploadDocFileName;
	private String uploadDocContentType;

    public String execute() {
	return SUCCESS;
	}

	public File getUploadDoc() {
		return uploadDoc;
	}

	public void setUploadDoc(File uploadDoc) {
		this.uploadDoc = uploadDoc;
	}

	public String getUploadDocFileName() {
		return uploadDocFileName;
	}

	public void setUploadDocFileName(String uploadDocFileName) {
		this.uploadDocFileName = uploadDocFileName;
	}

	public String getUploadDocContentType() {
		return uploadDocContentType;
	}

	public void setUploadDocContentType(String uploadDocContentType) {
		this.uploadDocContentType = uploadDocContentType;
	}
}

JSP Page

 
fileupload.jsp
 

<%@taglib uri="/struts-tags" prefix="s"%>
<html>
<head>
<title>file upload page</title>
</head>
<body>
	<h3>Struts 2 file upload example</h3>
	<s:form action="fileUpload" method="post" enctype="multipart/form-data">
	<s:file name="uploadDoc" label="Choose file to upload" />
	<s:submit value="upload" align="center" />
</s:form>
</body>
</html>

 
uploadSuccess.jsp
 

<%@taglib uri="/struts-tags" prefix="s"%>
<html>
<head>
<title>Upload Successful</title>
<s:head />
</head>
<body>

<h3>Struts 2 file upload example</h3>
 File Name :   <s:property value="uploadDocFileName"></s:property><br />
 Content type: <s:property value="uploadDocContentType"></s:property><br />
 User file :   <s:property value="uploadDoc"></s:property>
</body>
</html>

struts.xml

 
Make sure you have done action mapping properly in struts.xml file. An example of this is given below,

<struts>
<package name="" namespace="/jsp" extends="struts-default">
<action name="fileUpload" class="com.simplecode.action.FileUploadAction" >
	<interceptor-ref name="defaultStack"></interceptor-ref>
	<interceptor-ref name="fileUpload">
            <param name="maximumSize">1024000</param>
            <param name="allowedTypes">application/pdf</param>
	</interceptor-ref>
	<interceptor-ref name="validation">
		<param name="excludeMethods">input,back,cancel,browse</param>
	</interceptor-ref>
	<interceptor-ref name="workflow">
		<param name="excludeMethods">input,back,cancel,browse</param>
	</interceptor-ref>
	<result name="success">/jsp/uploadSuccess.jsp</result>
	<result name="input">/jsp/fileUpload.jsp</result>
</action>
</package>

</struts>

Demo

 http://localhost:8089/Struts2_FileUpload/

Error message prompts if you upload a file which is more than 10kb, or not a text file.

 
The uploaded file will be treat as a temporary file, with a long random file name, upload__376584a7_12981122379__8000_00000010.tmp. This file will be stored some where in the metadata directory
 

 

<constant name="struts.multipart.saveDir" value="D:/your folder"/>

Struts 2 – Upload File to Desire Folder Location

 
So in-order to upload and save a file in target space and in-order to have a file with proper extension, i.e .pdf , .doc etc, we should use the following code snippet in the action class’s execute method.
 
Modified execute method
 

public String execute()
{
// Location to store the uploaded file in our desired path
String targetPath = "D:/file target/";
File fileToCreate = new File(targetPath, uploadDocFileName);
	try
	{
		FileUtils.copyFile(this.uploadDoc, fileToCreate);
	}
	catch (IOException e)
	{
		addActionError(e.getMessage());
	}
	return SUCCESS;
}

Zip file – FileUpload.zip War file – FileUpload.war