【发布时间】：2009-12-22 07:45:16
【问题描述】：
您好，我想使用 jsp 和 servlet 上传图像（以及其他表单详细信息）并预览它们。我能够完成上传部分，但无法获得如何在前端预览图像。
我正在使用 YUI 来实现它。实际上，我正在尝试重用一个用 PHP 实现的示例。我在这里附上我的 Servlet 代码。上传完成后，此“completeFileName”将被填充。
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
if(completeFileName == null) {
PrintWriter pout = response.getWriter();
JSONObject obj = new JSONObject();
obj.put("hasError", new Boolean(true));
pout.println(obj.toString());
}
try {
OutputStream out = response.getOutputStream();
Image image = Toolkit.getDefaultToolkit().getImage(completeFileName);
ImageIcon icon = new ImageIcon(image);
int height = icon.getIconHeight();
int width = icon.getIconWidth();
BufferedImage bi = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
ImageIO.write(bi, "jpg", out);
out.flush();
} catch (Exception ex) {
}
我的 Jsp 代码如下所示：
<script type="text/javascript" src="http://yui.yahooapis.com/2.3.0/build/connection/connection.js"></script>
<script type="text/javascript" src="http://yui.yahooapis.com/2.3.0/build/utilities/utilities.js"></script>
<script type="text/javascript">
var $E = YAHOO.util.Event;
var $ = YAHOO.util.Dom.get;
var $D = YAHOO.util.Dom;
function init(){
var listImageHandler = {
success:function(o) {
var r = eval('(' + o.responseText + ')');
if(!r.hasError) {
var imageListCon = $('imageListCon');
var img = document.createElement('img');
//img.src = 'image.php?i=' + r.imageList[i];
img.src = r.fileName;
imageListCon.appendChild(img);
}
}
};
var onUploadButtonClick = function(e){
var uploadHandler = {
upload: function(o) {
//console.log(o.responseText);
$D.setStyle('indicator', 'visibility', 'hidden');
var r = eval('(' + o.responseText + ')');
if(r.hasError){
var errorString = '';
for(var i=0; i < r.errors.length; i++){
errorString += r.errors[i];
}
alert(errorString);
}else{
YAHOO.util.Connect.asyncRequest('GET', 'UploadFileServlet', listImageHandler);
}
}
};
$D.setStyle('indicator', 'visibility', 'visible');
//the second argument of setForm is crucial,
//which tells Connection Manager this is an file upload form
YAHOO.util.Connect.setForm('testForm', true);
YAHOO.util.Connect.asyncRequest('POST', 'UploadFileServlet', uploadHandler);
};
$E.on('uploadButton', 'click', onUploadButtonClick);
YAHOO.util.Connect.asyncRequest('GET', 'UploadFileServlet', listImageHandler);
}
$E.on(window, 'load', init);
</script>
</head>
<body>
<form action="UploadFileServlet" method="POST" enctype="multipart/form-data" id="testForm">
<input type="file" name="testFile"><br>
<input type="button" id="uploadButton" value="Upload"/>
</form>
<div class="restart"><a href="UploadFileServlet?redo=1">Redo It</a></div>
<div style="visibility:hidden; margin-bottom:1.5em;" id="indicator">Uploading... <img src="indicator.gif"/></div>
<div id="imageListCon">
</div>
</body>
我无法得到回复，有人可以帮忙吗？
谢谢， 阿米特
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标签： javascript jquery jsp servlets yui