Struts2 use annotations to upload and download files (i)

It is easy to upload and download files by using Commons FileUpload components in Struts2, Commons fileupload by saving HTTP data to a temporary folder. Struts then uses the FileUpload interceptor to bind the file to an instance of the action, so that we can manipulate the browser upload file as a local file. However, most of these examples need to be configured in the Struts.xml, more cumbersome, but the STRUTS2 provides a Struts2-convention-plugin plug-in, you can use annotations in the program to configure the action to make it more flexible.

The following is an introduction to using annotations to implement file uploads:

1. Add a dependent Jar pack

2. Configure Struts.xml files, where the struts file basically does not need to configure, such as:

<?xml version= "1.0" encoding= "UTF-8"?> <!
DOCTYPE struts public
	"-//apache Software foundation//dtd struts Configuration 2.3//en"
	"http:// Struts.apache.org/dtds/struts-2.3.dtd ">

<struts>
	<constant name=" Struts.enable.DynamicMethodInvocation "value=" true "/> <constant name=" Struts.devmode "value=
	" true "/>
	<constant name= "struts.convention.package.locators" value= "action"/>
	<!--Specify the maximum number of bytes allowed to upload. The default value is 2097152 (2M), using the struts constant to enlarge the default upload file size-->
	<constant name= "struts.multipart.maxSize" value= "104857600" ></constant>

</struts>

3. Write the file upload Action:FileUploadAction.java

Package com.figo.action;
Import Java.io.BufferedInputStream;
Import Java.io.BufferedOutputStream;
Import Java.io.File;
Import Java.io.FileInputStream;
Import Java.io.FileOutputStream;
Import Java.io.InputStream;
Import Java.io.OutputStream;
Import Org.apache.struts2.ServletActionContext;
Import org.apache.struts2.convention.annotation.Action;
Import Org.apache.struts2.convention.annotation.InterceptorRef;
Import Org.apache.struts2.convention.annotation.InterceptorRefs;
Import Org.apache.struts2.convention.annotation.Result;

Import Org.apache.struts2.convention.annotation.Results;

Import Com.opensymphony.xwork2.ActionSupport; @Action ("FileUpload") @InterceptorRefs (value = {@InterceptorRef ("Fileuploadstack")}) @Results ({@Result (name = Success ", location ="/result.jsp ")}) public class Fileuploadaction extends Actionsupport {private static final long s
	Erialversionuid = 572146812454l;
	private static final int buffer_size = 16 * 1024;
	Encapsulates the properties of an uploaded file field private file upload; Encapsulation onAttributes of the file type private String contentType;
	Encapsulates the attributes of an uploaded file name private String filename;

	Private String Storagefilename;

	Private String Storagepath; Since we are using <s:file name= "Upload" .../> The file itself'll be//obtained through Getter/setter
	;file-tag-name> Public File Getupload () {return upload;
	The public void Setupload (File upload) {this.upload = upload;
	Public String GetFileName () {return fileName;
	public void Setfilename (String fileName) {this.filename = filename; }//Since we are using <s:file name= "Upload" .../> the file name would be//obtained through getter/setter of &L
	T;file-tag-name>filename public String Getuploadfilename () {return FileName;
	public void Setuploadfilename (String fileName) {this.filename = filename;
	Public String Getstoragefilename () {return storagefilename;
	} public void Setstoragefilename (String storagefilename) {this.storagefilename = Storagefilename; }//SinCe we are using <s:file name= "Upload" .../> the content type would be//obtained through getter/setter of <file
	-tag-name>contenttype public String Getuploadcontenttype () {return ContentType;
	} public void Setuploadcontenttype (String contentType) {this.contenttype = ContentType;
	Public String getContentType () {return contentType;
	} public void setContentType (String contentType) {this.contenttype = ContentType;
			public void copy (file src, file dst) {try {inputstream in = null;
			OutputStream out = null;
				try {in = new Bufferedinputstream (new FileInputStream (SRC), buffer_size);
				out = new Bufferedoutputstream (new FileOutputStream (DST), buffer_size);
				byte[] buffer = new Byte[buffer_size];
				while (in.read (buffer) > 0) {out.write (buffer);
				finally {if (null!= in) {in.close ();
				} if (null!= out) {out.close ();
	A catch (Exception e) {e.printstacktrace ());	} public static string Getextention (string fileName) {int pos = Filename.lastindexof (".");
	Return filename.substring (POS); @Override public String Execute () throws Exception {//Storagefilename = new Date (). GetTime () + getextention (filen
		AME);
		Storagefilename = FileName;
		SYSTEM.OUT.PRINTLN ("FileName:" + filename);
		System.out.println ("ContentType:" + ContentType);
		System.out.println ("File:" + upload); 
		File Storagefile = new file (Servletactioncontext.getservletcontext (). Getrealpath ("/upload") + "/" + storagefilename);

		Copy (upload, storagefile);
	return SUCCESS; }

}

The fileuploadaction role is to copy the uploaded files from the browser to the upload folder of the Web application.

4. Write the Document upload form page upload.jsp:

<%@ page language= "java" contenttype= "text/html; Charset=utf-8 "
	pageencoding=" Utf-8 "%>
<%@ taglib prefix=" s "uri="/struts-tags "%>

<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd ">
Set the form's submission to post, and then set Enctype to Multipart/form-data, <s:file/> flag binds the file upload control to the upload property of the action.

5. Results return page result.jsp:


<%@ page language= "java" contenttype= "Text/html;charset=utf-8"
	pageencoding= "Utf-8"%> <%@, Taglib
Prefix= "S" uri= "/struts-tags"%>

<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd ">
 

6. Configure Web.xml:


<?xml version= "1.0" encoding= "UTF-8"?> <web-app xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance" xmlns= "Http://java.sun.com/xml/ns/javaee" xmlns:web= "http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi: schemalocation= "Http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id= "Webapp_ ID "version=" 3.0 "> <display-name>Upload</display-name> <filter> &LT;FILTER-NAME&GT;STRUTS2&L T;/filter-name> <filter-class>org.apache.struts2.dispatcher.ng.filter.strutsprepareandexecutefilter
            </filter-class> <init-param> <param-name>actionPackages</param-name> 
        <param-value>com.figo.action</param-value> </init-param> </filter> <filter> <filter-name>struts-cleanup</filter-name> <filter-class> Org.apache.strut S2.dispatcher.ActionContextCleanUp </filter-class> </filter> <filter-mapping> <filter-name>struts-cleanup</filter-name> <url-p attern>/*</url-pattern> </filter-mapping> <filter-mapping> <filter-name>struts2</f ilter-name> <url-pattern>/*</url-pattern> </filter-mapping> <welcome-file-list> ;welcome-file>index.html</welcome-file> <welcome-file>index.htm</welcome-file> < Welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app>
 

The key is to add <init-param>,actionpackages as the package that contains the action file in the filter.

7. Page Test:

File Upload page:



File Upload return Result:



Because it was tested in Eclipse Engineering, the file was saved in a temporary file, and if it was really published, the uploaded file would be saved to the predefined directory.

Note:

1. struts2 default maximum can upload 2M file, can enlarge the default file upload size in struts.xml.

2. The summary of commonly used annotations is as follows:

Namespace: Specifies the namespace.


Parentpackage: Specifies the parent package.

Result: Provides a mapping of action results (a mapping of results).

Results: List of "result" annotations.

Resultpath: Specifies the base path of the resulting page.

Action: Specifies the access URL for the action.

Actions: List of "Action" annotations.

Exceptionmapping: Specifies an exception mapping (mapping a Declaration exception).

Exceptionmappings: An array of first-level declaration exceptions.

Interceptorref: Interceptor Reference.

Interceptorrefs: Interceptor Reference Group.

Here is just to give you a good effect, the program itself is very simple, mainly configuration, the next article 0 profile download.

Source code Download Link: http://download.csdn.net/detail/sxwyf248/4462899