struts2 实现文件上传功能

 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 upload;
     private String uploadContentType;
     private String uploadFileName;
     private String imageFileName;
     private String caption;

     public File getUpload() {
		return upload;
	}
	public void setUpload(File upload) {
		this.upload = upload;
	}
	public String getUploadFileName() {
		return uploadFileName;
	}
	public void setUploadFileName(String uploadFileName) {
		this.uploadFileName = uploadFileName;
	}
	public String getUploadContentType() {
		return uploadContentType;
	}
	public void setUploadContentType(String uploadContentType) {
		this.uploadContentType = uploadContentType;
	}
     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(uploadFileName);
        File imageFile = new File(ServletActionContext.getServletContext().getRealPath( " /UploadImages " ) + " / " + imageFileName);
        copy(upload, imageFile);
         return SUCCESS;
    } 

} 

注意：在jsp中，表单的enctype属性设置为“multipart/form-data”， <s:file name="xxx" />应该对应Action类里面的File xxx、String xxxContentType和String xxxFileName三个属性，并生成getter，setter 方法。