FileBean.java

public class FileBean {
    private UploadedFile file;
    
    public void setUploadedFile(UploadedFile file) {
        this.file = file;
    }

    public UploadedFile getUploadedFile() {
        return file;
    }
}

Page.java

public class Page {
    @Property 
    private List<FileBean> fileBeans;
    
    @Property
    private FileBean fileBean;
    
    public ValueEncoder<FileBean> getFileBeanEncoder() {
        return new ValueEncoder<FileBean> {
            public String toClient(V value) {
                return "placeholder";
            }
            
            // tapestry will call this for each placeholder on the client
            // it will call FileBean.setUploadedFile() with the UploadedFile instance
            public FileBean toValue(String client) {
                if (fileBeans == null) {
                    fileBeans = new ArrayList<FileBean>();
                }
                FileBean value = new FileBean();
                fileBeans.add(value);
                return value;
            }
        };
    }
    
    public FileBean onAddRow() {
        // initialize the fileBean property so that tapestry can render another row
        fileBean = new FileBean();
        
        // return the fileBean instance so that tapestry can store a placeholder on the client
        return fileBean;
    }
    
    public void onSuccess() {
        doStuff(fileBeans);
    }
}

Page.tml

<t:ajaxformloop source="fileBeans" value="fileBean" encoder="fileBeanEncoder">
   <t:upload t:value="fileBean.uploadedFile" />
</t:ajaxformloop>