struts2中文件上传的实现

使用了apache的common-fileupload组件，同时还依赖与common-io包，使用之前，需要引入这两个包。

common-upload组件是把文件先上传到一个临时目录，然后需要自己手动在Action中处理，将文件改名，并且复制到指定的目录。

首先，创建文件上传页面：

<% @ 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" >
< html xmlns ="http://www.w3.org/1999/xhtml" >
< head >
< title > Struts 2 File Upload </ title >
</ head >
< body >
< s:form action ="fileUpload" method ="POST" enctype ="multipart/form-data" >
< s:file name ="myFile" label ="Image File" />
< s:textfield name ="caption" label ="Caption" />
< s:submit />
</ s:form >
</ body >
</ html >

需要注意的就是from中的enctype ="multipart/form-data"，还有要注意file标签的name值，要和后台Action中的名字一致，下面看一下Action代码。
package tutorial;

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 java.util.Date;

import org.apache.struts2.ServletActionContext;

import com.opensymphony.xwork2.ActionSupport;

public class FileUploadAction extends ActionSupport {
private static final long serialVersionUID = 572146812454l ;
private static final int BUFFER_SIZE = 16 * 1024 ;

private File myFile;
private String contentType;
private String fileName;
private String imageFileName;
private String caption;

public void setMyFileContentType(String contentType) {
this .contentType = contentType;
}

public void setMyFileFileName(String fileName) {
this .fileName = fileName;
}

public void setMyFile(File myFile) {
this .myFile = myFile;
}

public String getImageFileName() {
return imageFileName;
}

public String getCaption() {
return caption;
}

public void setCaption(String caption) {
this .caption = caption;
}

private static 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();
}
}
} catch (Exception e) {
e.printStackTrace();
}
}

private static String getExtention(String fileName) {
int pos = fileName.lastIndexOf( " . " );
return fileName.substring(pos);
}

@Override
public String execute() {
imageFileName = new Date().getTime() + getExtention(fileName);
File imageFile = new File(ServletActionContext.getServletContext().getRealPath( " /UploadImages " ) + " / " + imageFileName);
copy(myFile, imageFile);
return SUCCESS;
}

}

其中的FileName和contentType是common-upload组件会自己赋值的，只要写上这两个固定的名字就行了。特别特别需要注意的是这两个方法的set方法，不要使用myeclipse自动生成set方法，而是setMyFileFileName，看到有什么区别了吧，函数名中加了一个MyFile，这个是我们自定义的用于接收传过来的文件的对象。如果把这里写错了，就会报空指针错，这里一定要特别注意!
把文件上传到了网站根目录下的UploadImages下，这个文件夹需要自己手动创建，不然会提示没有权限。

接下来是struts.xml

<? xml version="1.0" encoding="UTF-8" ?>

<! DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd" >

< struts >
< package name ="fileUploadDemo" extends ="struts-default" >
< action name ="fileUpload" class ="tutorial.FileUploadAction" >
< interceptor-ref name ="fileUploadStack" />
< result name ="success" > /ShowUpload.jsp </ result >
</ action >
</ package >
</ struts >
注意其中的interceptor-ref属性的配置。

web.xml没什么区别，就不贴出来了。