我有一个 JSF 页面,上面有 8 张图片。
*仅适用于 jquery 查看器:请不要与 JSf 语法混淆。在幕后,它全部转换为纯 HTML。像 h:panelGrid 转换成表格元素。p:graphicImage 转换为 img 元素。实际上我想知道使用 jQuery ajax 加载图像的逻辑。就像使用 jQuery 一样,我调用服务器,然后从数据库中获取图像,当图像完全加载到路径上时,我更改 img src 属性以使用加载的图像更改默认图像。当页面在默认路径上加载时,会有一个默认图像,如 /resources/images/no-preview.jpg。所以我希望在加载图像时将其替换为 /resources/images/Image1.jpg、/resources/images/Image2.jpg 等 *。
<h:panelGrid columns="5" width="10%" style="position: relative; top: 50px; "
columnClasses="asteriskColumns, nameColumns" >
<h:outputText value="*" />
<h:outputText value="Map: " />
<p:fileUpload id="cityMap" widgetVar="uploader" description="Image"
update="city" allowTypes="*.jpg;*.png;*.gif;*.jpeg;"
auto="true" fileUploadListener="#{cityDetail.imageUpload}"
style="position: relative;" >
</p:fileUpload>
<p:graphicImage id="city" value="#{cityDetail.imagePath}" width="80"
height="50" cache="false" style="position: relative;">
<f:event type="preRenderComponent" listener="#{cityDetail.putImage}" />
</p:graphicImage>
<h:commandLink value="remove" title="Remove Picture"
style="color: #0d5b7f;text-decoration: underline;"
onclick="if (! confirm('Are you sure, you want to remove picture?') ) { return false;}; return true; ">
<f:ajax event="click" render="city" listener="#{cityDetail.removeImage}"/>
</h:commandLink>
.....
7 more images in same format
</h:panelGrid>
在构造函数中,我正在起诉这样的事情来从数据库中获取图像
public class CountryPages_Detail {
private String imagePath = "/resources/images/no-preview.jpg";
String path = externalContext.getRealPath("/resources/images") + "/" ;
public CountryPages_Detail() {
....
String cityMapQuery = "SELECT citymap From city Where cityid='" + cityID + "'";
String countryMapFileName = "countryMap_" + saarcCountryId;
// 7 more queries in same format
ArrayList countryMapQueryArray = addCredentialsToList(externalContext, countryMapQuery, countryMapFileName, response);
//7 more
ArrayList mainArray = new ArrayList();
mainArray.add(countryMapQueryArray);
...
ArrayList result = ConnectionUtil.showImagesFormDatabase(mainArray);
} //end of constructor
} //end of class CountryPages_Detail
public static ArrayList showImagesFormDatabase(ArrayList list) {
for (int i = 0; i < list.size(); i++) {
ArrayList fileCredentialsList = ((ArrayList) list.get(i));
String query = fileCredentialsList.get(0).toString();
sqlStatement = conn.createStatement();
resultSet = sqlStatement.executeQuery(query);
if (resultSet != null) {
while (resultSet.next()) {
imageBytes = resultSet.getBytes(1);
setResponceForDatabaseImages(fileCredentialsList);
imageName = createFile(fileCredentialsList, imageBytes);
if (imageName != null) {
imageNameList.add(imageName);
}
} //end of while()
} //end of if()
} //end of for()
return imageNameList;
} //end of showImagesFormDatabase()
如您所见,我在页面加载时从数据库中获取图像。从数据库中获取图像字节,然后在该字节的路径上创建图像文件。但我有 8 张图片。如果任何图像尺寸很大,那么我必须等待,这令人沮丧。
我希望在页面加载时,而不是从数据库中加载图像,而是使用 ajax。意味着我的页面的其余部分会加载,图像会从幕后加载,当所有图像都加载后,就会显示在 p:graphicImage 中的图像。在加载图像时,加载图标应该显示在 p:grahicImage 中,当图像完全加载时,图标消失并且应该显示图像。
我该怎么做?
谢谢
编辑: - - - - - - - - - - - - - - - - - - - - - - - - ----------------------------------
<ui:define name="content">
<h:form id="faqAddUpdateForm" prependId="false">
<h:panelGrid columns="5" width="10%" style="position: relative; top: 50px; "
columnClasses="asteriskColumns, nameColumns" >
....
</h:panelGrid>
</h:form>
<h:form id="hidden" style="display:none">
<h:commandLink id="link">
<f:ajax event="click" listener="#{countryPages_Detail.loadImagesUsingAjax}" />
</h:commandLink>
</h:form>
<script>
window.onload = function() {
document.getElementById('hidden:link').onclick();
}
</script>
</ui:define>