通过传统的form表单提交的方式上传文件：

<form id= "uploadForm" action= "http://localhost:8080/cfJAX_RS/rest/file/upload" method= "post" enctype ="multipart/form-data">
  <h1 >测试通过Rest接口上传文件 </h1>
  <p >指定文件名： <input type ="text" name="filename" /></p>
  <p >上传文件： "file" "file" /><p >关键字1： "keyword" /><p >关键字2： <p >关键字3： "submit" value="上传"/>
</form>

不过传统的form表单提交会导致页面刷新，但是在有些情况下，我们不希望页面被刷新，这种时候我们都是使用Ajax的方式进行请求的：

$.ajax({
  url : "http://localhost:8080/STS/rest/user",  type "POST",  data : $( '#postForm').serialize(),  success : function(data) {
    '#serverResponse').html(data);
  },  error '#serverResponse').html(data.status + " : " + data.statusText + " : " + data.responseText);
  }
});

关于FormData及其用法

这里只展示一个通过from表单来初始化FormData的方式

<formenctype="multipart/form-data"method="post"name="fileinfo">

var oData = new FormData(document.forms.namedItem("fileinfo" ));
oData.append( "CustomField","This is some extra data" );
var oReq = new XMLHttpRequest();
oReq.open( "stash.php",true );
oReq.onload = function(oEvent) {
      if (oReq.status == 200) {
          oOutput.innerHTML = "Uploaded!" ;
     } else {
          oOutput.innerHTML = "Error " + oReq.status + " occurred uploading your file.<br />";
     }
};
oReq.send(oData);

参见：https://developer.mozilla.org/zh-CN/docs/Web/Guide/Using_FormData_Objects

uploadForm">
      type="filename" value= ""/></p >
      "file"/></ p>
      "button" "上传" onclick="doUpload()" />
</form>

function doUpload() {
  var formData = new FormData($( "#uploadForm" )[0]);
  $.ajax({
    url: 'http://localhost:8080/cfJAX_RS/rest/file/upload',    type: 'POST',    data: formData,    async: false,    cache: false,    contentType: false,    processData: false,    success: function (returndata) {
        alert(returndata);
    },    error: function (returndata) {
    alert(returndata);
}
});
}