org.apache.commons.fileupload.FileUploadException: the request was rejected because no multipart bou

upload.jsp<%@ page language="java" contentType="text/html; charset=gbk"
   pageEncoding="gbk"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gbk">
<title>Insert title here</title>
 <script type="text/javascript">
        var xmlHttp;
        //创建XMLhttpRequest对象
        function createXMLHttpRequest() {
            if (window.ActiveXObject) {
                xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
            }
            else if (window.XMLHttpRequest) {
                xmlHttp = new XMLHttpRequest();
            }
        }        //生成传递到服务器的参数查询串，参数值由页面表单填写得到
       function createQueryString() {
            var firstName = document.getElementById("firstName").value;
            var queryString = "firstName=" + firstName + "";
            return queryString;
        }
      //点击按钮响应的POST方法主函数
        //POST方法把参数值以名=值方式在xmlHttp.send(queryString)中传递,queryString的形式为参数名=值&参数名=值...;
        function doRequestUsingPOST() {
            createXMLHttpRequest();//第一步：创建XMLHttpRequest对象
            var url = "fff";
            var queryString = createQueryString();//第二步：定义传递的参数值字符串
            xmlHttp.open("POST", url, true);//第三步：建立与服务器的请求
            xmlHttp.onreadystatechange = handleStateChange;//第四步：监听状态-->转到监听状态函数
            xmlHttp.setRequestHeader("Content-Type","multipart/form-data;");
            xmlHttp.send(null);//第五步：发送请求，并且立即返回
        }        //监听状态函数
        function handleStateChange() {
            if(xmlHttp.readyState == 4) {
                if(xmlHttp.status == 200) {
                parseResults();//-->转到函数parseResults输出从服务器返的值
                }
            }
        }        //在页面显示从服务器传来的结果
       function parseResults() {
            var responseDiv = document.getElementById("serverResponse");
            if(responseDiv.hasChildNodes()) {
            responseDiv.removeChild(responseDiv.childNodes[0]);
        }
        var responseText = document.createTextNode(xmlHttp.responseText);//
        responseDiv.appendChild(responseText);
        }
</script>
</head>
<body> <input type="file" size="30" id="firstName" name="test" />
<input name="up" type="button" onclick="doRequestUsingPOST();" value="上传" />
<div id="serverResponse"></div>

</body>
</html>UploadFile.javapublic class UploadFile extends HttpServlet {    protected void processRequest(HttpServletRequest request,
            HttpServletResponse response, String method)
            throws ServletException, IOException {
    
        final long MAX_SIZE = 3 * 1024 * 1024;

final String[] allowedExt = new String[] { "jpg","gif" };
response.setContentType("text/html;charset=gbk");

response.setCharacterEncoding("gbk");
DiskFileItemFactory dfif = new DiskFileItemFactory();
dfif.setSizeThreshold(4096);
dfif.setRepository(new File(request.getRealPath("/")
+ "ImagesUploadTemp"));
ServletFileUpload sfu = new ServletFileUpload(dfif);

sfu.setSizeMax(MAX_SIZE); PrintWriter out = response.getWriter();

List fileList = null;
try {
fileList = sfu.parseRequest(request);
} catch (FileUploadException e) {
if (e instanceof SizeLimitExceededException) {
out.println("请选择小于等于:" + MAX_SIZE + "的文件<p />");
out.println("<a href=\"upload.html\" target=\"_top\">返回</a>");
return;
}
e.printStackTrace();
}

if (fileList == null || fileList.size() == 0) {
out.println("11");
out.println("<a href=\"upload.html\" target=\"_top\">返回</a>");
return;
}
Iterator fileItr = fileList.iterator();

while (fileItr.hasNext()) {
FileItem fileItem = null;
String path = null;
long size = 0;

fileItem = (FileItem) fileItr.next();
if (fileItem == null || fileItem.isFormField()) {
continue;
}
path = fileItem.getName();
size = fileItem.getSize();
if ("".equals(path) || size == 0) {
out.println("你选择的文件不正确 ");
out.println("<a href=\"upload.html\" target=\"_top\">返回</a>");
return;
}
String t_name = path.substring(path.lastIndexOf("\\") + 1);
String t_ext = t_name.substring(t_name.lastIndexOf(".") + 1);
int allowFlag = 0;
int allowedExtCount = allowedExt.length;
for (; allowFlag < allowedExtCount; allowFlag++) {
if (allowedExt[allowFlag].equals(t_ext))
break;
}
if (allowFlag == allowedExtCount) {
out.println("支撑的文件格式<p />");
for (allowFlag = 0; allowFlag < allowedExtCount; allowFlag++)
out.println("*." + allowedExt[allowFlag]
   + "&nbsp;&nbsp;&nbsp;");
   out.println("<p /><a href=\"upload.html\" target=\"_top\">返回</a>");
return;
}
long now = System.currentTimeMillis();
String prefix = String.valueOf(now);
String u_name = request.getRealPath("/") + "ImagesUploaded/"
+ prefix + "." + t_ext;
try {

fileItem.write(new File(u_name));
out.println("文件名称: " + prefix + "." + t_ext
+ " &nbsp;&nbsp;文件大小: " + size + "<p />");
out.println("<a href=\"upload.html\" target=\"_top\">返回</a>");
} catch (Exception e) {
e.printStackTrace();
}


}
                out.println("123");
                out.close();
            }
            protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
                //Get主函数调用processRequest,完成Get方法的参数接受，返回的过程
                processRequest(request, response, "GET");
            }
            protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
                //POST主函数调用processRequest,完成POST方法的参数接受，返回的过程
                processRequest(request, response, "POST");
            }
}
报的错误
org.apache.commons.fileupload.FileUploadException: the request was rejected because no multipart boundary was found
at org.apache.commons.fileupload.FileUploadBase$FileItemIteratorImpl.<init>(FileUploadBase.java:814)
at org.apache.commons.fileupload.FileUploadBase.getItemIterator(FileUploadBase.java:323)
at org.apache.commons.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:341)
at org.apache.commons.fileupload.servlet.ServletFileUpload.parseRequest(ServletFileUpload.java:126)
at UploadFile.processRequest(UploadFile.java:47)
at UploadFile.doPost(UploadFile.java:124)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:228)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:216)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:634)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:445)
at java.lang.Thread.run(Unknown Source)