在Struts2中，上傳檔案時，只要使用java.io.File類來描述上傳檔案即可，比直接使用Commons-FileUpload元件要簡單的多。

如果上傳的是單個檔案，則在Action類中定義一個File型別的變數。該變數的名字與JSP頁面上的<input />標籤的name屬性相對應，只有這樣Struts2才能使客戶端上傳的檔案自動與Action類中的相應的屬性進行關聯處理。

如果上傳的是多個檔案，這時在JSP頁面中的所有的<input type="file" name="upload" />標籤的name屬性值都必須相同，這時Action中相對應的屬性就要使用List或File[]用來表示多個檔案的資訊。

儲存檔案相關屬性的變數設定如下：

private List<File> upload;   //儲存上傳的檔案
private List<String> uploadContentType;	 //儲存上傳的檔案型別
private List<String> uploadFileName;   //儲存上傳的檔名

以下是一個使用Struts 2上傳多個檔案的例子，把上傳的檔案重新用生成的隨機數命名：

public class UploadFilesAction extends ActionSupport {

	private List upload;
	private List uploadContentType;
	private List uploadFileName;
	private String uploadPath;
	private String result;
	private boolean success;
	private String msg;
	public boolean isSuccess() {
		return success;
	}
	public String getMsg() {
		return msg;
	}
	public String getResult() {
		return result;
	}
	public void setUpload(List upload) {
		this.upload = upload;
	}
	public void setUploadContentType(List uploadContentType) {
		this.uploadContentType = uploadContentType;
	}
	public void setUploadFileName(List uploadFileName) {
		this.uploadFileName = uploadFileName;
	}
	public void setUploadPath(String uploadPath) {
		this.uploadPath = uploadPath;
	}
	public String execute() throws Exception {
		for (int i = 0; i < uploadFileName.size(); i++) {
                        Random random = new Random();
                        String filename = uploadFileName.get(i);                         
                        //把上傳的檔案用生成的隨機數重新命名
                        //並判斷生成的檔名是否已經存在
                        //如果存在，則繼續生成隨機數命名，直到找打還沒使用的隨機數為止
                        filename = uploadPath + random.nextLong()
                                + filename.substring(filename.lastIndexOf("."));
                        while (new File(filename).exists()) {
                            filename = uploadPath + random.nextLong()
                                    + filename.substring(filename.lastIndexOf("."));
                        }
                        FileOutputStream fos = new FileOutputStream(filename);
                        InputStream is = new FileInputStream(upload.get(i));
                        byte[] buffer = new byte[8192];
                        int count = 0;
                        while ((count = is.read(buffer)) > 0) {
                            fos.write(buffer, 0, count);
			}
			fos.close();
			is.close();
		}
		success=true;
		msg = "檔案上傳成功！";
		return "result";
	}
}

<package name="struts2" namespace="/" extends="struts-default">
	<action name="uploadFiles"
            class="uploadtest.actions.UploadFilesAction">
		<result name="result">/WEB-INF/result.jsp</result>
		<param name="uploadPath">D:\UploadFiles\</param>
	</action>
</package>