缓慢拖动;在JSF页面中删除JPG图片

Question

在我的JSF应用程序中，我想拖放JPEG图片（30张图片大小约为10Mo），我正面对一个慢速充电页面和图片。 我正在使用以下代码压缩这些图片：

    public void reduceImageQuality(int sizeThreshold, UploadedFile file, String destImg) throws Exception {
    float quality = 0.05f;
    long fileSize = file.getSize();
    if (fileSize <= sizeThreshold) {
        System.out.println("Image file size is under threshold");
        return;
    }
    Iterator iter = ImageIO.getImageWritersByFormatName("jpeg");

    ImageWriter writer = (ImageWriter) iter.next();

    ImageWriteParam iwp = writer.getDefaultWriteParam();

    iwp.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
    BufferedImage originalImage = ImageIO.read(file.getInputstream());
    IIOImage image = new IIOImage(originalImage, null, null);

    float percent = 0.01f;   // 10% of 1  

    while (fileSize > sizeThreshold) {
        if (percent >= quality) {
            percent = percent * 0.1f;
        }
        quality -= percent;
        File fileOut = new File(destImg);
        if (fileOut.exists()) {
            fileOut.delete();
        }
        try (FileImageOutputStream output = new FileImageOutputStream(fileOut)) {
            writer.setOutput(output);

            iwp.setCompressionQuality(quality);

            writer.write(null, image, iwp);

            File fileOut2 = new File(destImg);
            long newFileSize = fileOut2.length();
            if (newFileSize == fileSize) {
                // cannot reduce more, return  
                break;
            } else {
                fileSize = newFileSize;
            }
            System.out.println("quality = " + quality + ", new file size = " + fileSize);
        }
    }

    writer.dispose();
}

对于我的XHTML代码：

    <h:form id="firstGenForm"    enctype="multipart/form-data" >
    <h:panelGrid columns="1" style="margin-left:40px;">  
        <p:outputPanel id="imageForPenetrationPointPublic" styleClass="slot">  
            <h:panelGrid columns="1"  rendered="#{generationTdeEbmMB.selectedImageForPenetrationPointPublic!= null}">
                <p:graphicImage   url="/images/#{generationTdeEbmMB.selectedImageForPenetrationPointPublic}" style="width: 100%;height: 260px;"/> 
            </h:panelGrid>
        </p:outputPanel>

        <p:droppable for="imageForPenetrationPointPublic" tolerance="fit" activeStyleClass="ui-state-highlight" datasource=":availablePictureForm:availablePicturesDGrid" onDrop="handleDrop">
            <p:ajax listener="#{generationTdeEbmMB.onImageForPenetrationPointPublicDrop}" update="imageForPenetrationPointPublic " />
        </p:droppable>
    </h:panelGrid>
</h:form>
<h:form id="availablePictureForm" >
    <p:fieldset legend="Photos disponibles " rendered="#{generationTdeEbmMB.uploadedImageNameList.size() != 0}">  
        <p:scrollPanel style="width:400px;height: 600px;">
            <p:dataGrid id="availablePicturesDGrid" value="#{generationTdeEbmMB.uploadedImageNameList}" var="imageName"  columns="3" emptyMessage="Aucune photo trouvée.">
                <p:panel id="pnl" header="#{imageName}" style="text-align:center">
                    <h:panelGrid columns="1" style="width:20%">

                        <p:graphicImage   url="/images/#{imageName}" style="width: 120px;height: 110px;"/>                  
                    </h:panelGrid>
                </p:panel>
                <p:draggable for="pnl" proxy="true" revert="true"  helper="clone" handle=".ui-panel-content" stack=".ui-panel"/>
            </p:dataGrid>
        </p:scrollPanel>
    </p:fieldset>
</h:form>

但缓慢的问题仍然存在。如果不纠正这个问题，我什么也做不了。 我正在使用JSF 2.1和PrimeFaces 3.5

欢迎任何建议或想法。

非常感谢提前。