GWT将表单参数发送到一个servlet [英] GWT Send form parameters to a servlet

问题描述

源代码与其中的代码是一样的。

我试图在一个servlet中捕获接下来两个突出显示的字段，我可以获取上传的文件。显示在 GWT FormSubmit class Javadoc

  form.setEncoding（FormPanel.ENCODING_MULTIPART）; 
 form.setMethod（FormPanel.METHOD_POST）; 
 
 //创建一个面板来容纳所有的表单小部件。 
 VerticalPanel面板=新的VerticalPanel（）; 
 form.setWidget（panel）; 
 
 //创建一个文本框，给它一个名字以便它被提交。 
 final TextBox tb = new TextBox（）; 
 tb.setName（WorkTitle）; 
 tb.setValue（WorkTitle）; 
 
 panel.add（tb）; 
 
 //创建一个ListBox，给它一个名字和一些与
 //和
 //其选项关联的值。 
 ListBox lb = new ListBox（）; 
 lb.setName（listBoxFormElement）; 
 lb.addItem（foo，fooValue）; 
 lb.addItem（bar，barValue）; 
 lb.addItem（baz，bazValue）; 
 panel.add（lb）; 
 
 //创建一个FileUpload小部件。 
 FileUpload upload = new FileUpload（）; 
 upload.setName（uploadFormElement）; 
 panel.add（上传）; 
 
 //添加一个'提交'按钮。 
 panel.add（new Button（Submit，new ClickListener（）{
 public void onClick（Widget sender）{
 form.setAction（GWT.getModuleBaseURL（）+uploadWork） ; 
 form.submit（）; 
} 
}））; 
  

我在servlet中使用这些代码行获取这些参数：

  protected void doPost（HttpServletRequest req，HttpServletResponse resp）
抛出ServletException，IOException {
 System.out.println（ENTRAA BIENNNN ）; 
 System.out.println（___ELEMENTO1+ req.getAttribute（WorkTitle））; 
 System.out.println（___ELEMENTO3+ req.getParameterValues（WorkTitle））; 
  

但两者都会返回 NULL p>

我该怎么办？

TIA！

解决方案

大多数servlet容器不会自动解码 multipart / form-data ，所以 req.getParameter （或 getParameterValues 或类似的getter）不会返回任何内容。

您必须使用库 Apache Commons FileUpload 或 Jetty的 MultiPartFilter 来解码 multipart / form-data 有效载荷。 / p>

请注意， req.getAttribute 与从请求中获取数据无关;它用于在服务器组件之间（servlet容器和servlet之间，或者过滤器和servlet之间）传递与请求相关的数据。

I´m trying to catch the next two highlighted fields in a servlet where I can get the uploaded file.

The source code is just the same as which is shown in a GWT FormSubmit class Javadoc

form.setEncoding(FormPanel.ENCODING_MULTIPART);
form.setMethod(FormPanel.METHOD_POST);

// Create a panel to hold all of the form widgets.
VerticalPanel panel = new VerticalPanel();
form.setWidget(panel);

// Create a TextBox, giving it a name so that it will be submitted.
final TextBox tb = new TextBox();
tb.setName("WorkTitle");
tb.setValue("WorkTitle");

panel.add(tb);

// Create a ListBox, giving it a name and some values to be associated
// with
// its options.
ListBox lb = new ListBox();
lb.setName("listBoxFormElement");
lb.addItem("foo", "fooValue");
lb.addItem("bar", "barValue");
lb.addItem("baz", "bazValue");
panel.add(lb);

// Create a FileUpload widget.
FileUpload upload = new FileUpload();
upload.setName("uploadFormElement");
panel.add(upload);

// Add a 'submit' button.
panel.add(new Button("Submit", new ClickListener() {
    public void onClick(Widget sender) {
        form.setAction(GWT.getModuleBaseURL()+"uploadWork");
        form.submit();
    }
}));

I´m getting these parameters with this code lines in my servlet:

protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
    System.out.println("ENTRAA BIENNNN");
    System.out.println(" ___ELEMENTO1" + req.getAttribute("WorkTitle"));
    System.out.println(" ___ELEMENTO3" + req.getParameterValues("WorkTitle"));

But both returns me NULL.

How could I do?

TIA!

解决方案

Most servlet containers do not decode multipart/form-data automatically, so req.getParameter (or getParameterValues or similar getters) won't return anything.
You'll have to use a library such as Apache Commons FileUpload, or Jetty's MultiPartFilter to decode multipart/form-data payload.

As a side note, req.getAttribute has nothing to do with getting data out of the request; it's used to pass data, related to a request, between server components (between the servlet container and servlets, or between a filter and a servlet, for instance)

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