下面是FileUpload构件的一般用法，详细示例可参考 bpdemos。

首先创建托管Bean：

@ManagedBean(name = "interact.fileUploadBean", scope = ManagedBeanScope.REQUEST)
public class FileUploadBean {
    private UIFileUpload fileUpload1;
    private String errorMessage;

    public void processUpload(FileUploadItem fileUploadItem) {
        if (fileUploadItem.getFieldName().equals("fileUpload1"))
            deleteOldFiles();

        InputStream input = null;
        FileOutputStream output = null;

        try {
            input = fileUploadItem.openStream();
            output = new FileOutputStream(new File(getSaveToPath(fileUploadItem)));
            byte[] buf = new byte[4096];
            // UIFileUpload.END_UPLOADING为-1，这里表示数据输入流已经读取完毕
            int length = UIFileUpload.END_UPLOADING;

            while ((length = input.read(buf)) != UIFileUpload.END_UPLOADING) {
                output.write(buf, 0, length);
            }
        } catch (IOException e) {
            throw new FacesException(e);
        } finally {
            if (output != null)
                try {
                    output.close();
                } catch (IOException e) {
                }
        }
    }

    ...... 

}

下面是页面代码：

<w:fileUpload id="fileUpload1" uploadListener="#{interact.fileUploadBean.processUpload}"
    binding="#{interact.fileUploadBean.fileUpload1}" rich="true" maxSize="100k"
    required="true" />
<br />
<w:fileUpload id="fileUpload2" uploadListener="#{interact.fileUploadBean.processUpload}"
    rich="false" maxSize="100k" />
<br />
<w:fileUpload id="fileUpload3" writeTo="#{interact.fileUploadBean.fileUpload3WriteTo}"
    rich="true" browseIcon="images/select.gif" maxSize="100k" />
<br />
<w:button action="#{interact.fileUploadBean.action}" value="Upload" />
<w:fileUploadProgress startMessage="开始上传"
    uploadingMessage="正在上传，已经上传{readBytes}k/{total}k({percentage}%)"
    completeMessage="上传结束，总共{total}k" errorMessage="上传错误：{error}" />