obe*_*ger 21 java html5 servlets file-upload
我的问题就是说了这一切.我目前正在使用Uploadify(Flash + Ajax)到Servlet(Commons Upload w/OWASP ESAPI overlay)成功,但我想知道如何构建HTML5支持,或者更确切地说是支持Flash的HTML5.
我知道如何使HTML5 DnD工作,但我无法弄清楚Java Servlet连接和/或后端的机制.我搜索了很多地方,但我找不到任何答案,所以任何帮助都是值得赞赏的.
Bal*_*usC 46
我知道如何使HTML5 DnD工作,但我无法弄清楚Java Servlet连接和/或后端的机制.
它与使用常规时没有什么不同<form enctype="multipart/form-data">.您需要做的就是让HTML5/JS代码发送multipart/form-data带有删除文件的请求,这与我们使用常规<input type="file">字段发送的请求完全相同.我假设您无法弄清楚如何使用HTML5/JS实现这一目标.
您可以使用新的HTML5 File API,XHR2 FormData和XMLHttpRequestUploadAPI.
以下是您的drop事件处理程序应如何显示的启动示例:
function dropUpload(event) {
event.stopPropagation();
event.preventDefault();
var formData = new FormData();
formData.append("file", event.dataTransfer.files[0]);
var xhr = new XMLHttpRequest();
xhr.open("POST", "uploadServlet");
xhr.send(formData);
}
而已.此示例假定servlet映射到URL模式/uploadServlet.在此示例中,该文件随后在Apache Commons FileUpload中以常用方式提供,作为FileItem字段名称为的实例file.
有关更高级的内容,例如附加事件处理程序以监控进度等,请查看以下博客:
我用下面的SSCCE玩了一下:
<!DOCTYPE html>
<html lang="en">
<head>
<title>HTML5 drag'n'drop file upload with Servlet</title>
<script>
window.onload = function() {
var dropbox = document.getElementById("dropbox");
dropbox.addEventListener("dragenter", noop, false);
dropbox.addEventListener("dragexit", noop, false);
dropbox.addEventListener("dragover", noop, false);
dropbox.addEventListener("drop", dropUpload, false);
}
function noop(event) {
event.stopPropagation();
event.preventDefault();
}
function dropUpload(event) {
noop(event);
var files = event.dataTransfer.files;
for (var i = 0; i < files.length; i++) {
upload(files[i]);
}
}
function upload(file) {
document.getElementById("status").innerHTML = "Uploading " + file.name;
var formData = new FormData();
formData.append("file", file);
var xhr = new XMLHttpRequest();
xhr.upload.addEventListener("progress", uploadProgress, false);
xhr.addEventListener("load", uploadComplete, false);
xhr.open("POST", "uploadServlet", true); // If async=false, then you'll miss progress bar support.
xhr.send(formData);
}
function uploadProgress(event) {
// Note: doesn't work with async=false.
var progress = Math.round(event.loaded / event.total * 100);
document.getElementById("status").innerHTML = "Progress " + progress + "%";
}
function uploadComplete(event) {
document.getElementById("status").innerHTML = event.target.responseText;
}
</script>
<style>
#dropbox {
width: 300px;
height: 200px;
border: 1px solid gray;
border-radius: 5px;
padding: 5px;
color: gray;
}
</style>
</head>
<body>
<div id="dropbox">Drag and drop a file here...</div>
<div id="status"></div>
</body>
</html>
这UploadServlet利用了新的Servlet 3.0 HttpServletRequest#getPart()API:
@MultipartConfig
@WebServlet("/uploadServlet")
public class UploadServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
Part file = request.getPart("file");
String filename = getFilename(file);
InputStream filecontent = file.getInputStream();
// ... Do your file saving job here.
response.setContentType("text/plain");
response.setCharacterEncoding("UTF-8");
response.getWriter().write("File " + filename + " successfully uploaded");
}
private static String getFilename(Part part) {
for (String cd : part.getHeader("content-disposition").split(";")) {
if (cd.trim().startsWith("filename")) {
String filename = cd.substring(cd.indexOf('=') + 1).trim().replace("\"", "");
return filename.substring(filename.lastIndexOf('/') + 1).substring(filename.lastIndexOf('\\') + 1); // MSIE fix.
}
}
return null;
}
}