从JSP到Servlet读取不同的参数

Question

In my JSP, I have one drop down box and a table of items (using for loop) with each item being its own form all going to the same servlet. My issue is where to put the drop down box selection. I don't want to put it in the item form because it will have a drop down for each item. But if I make a separate form, I can't get the drop down parameter from the servlet when I submit the item form. I need to grab the drop down parameter and the item parameters. Any ideas on approaching this? Is there a way to have a hidden input in item form that stores the selected values from the drop down form? I'm not using any javascript.

Answer 1

Put it in some other form. On every item form make one hidden field.

<select id="DD">
  <option value="1">1</option>
  <option value="2">2</option>
  <!-- so on ... -->
</select>

<form id="i1">
<input type="hidden" id="dropDownValue" value="">
<!-- your code -->
</form>
<form id="i2">
<input type="hidden" id="dropDownValue" value="">
<!-- your code -->
</form>
<form id="i3">
<input type="hidden" id="dropDownValue" value="">
<!-- your code -->
</form>
<form id="i3">
<input type="hidden" id="dropDownValue" value="">
<!-- your code -->
</form>

Now , before submit set the value of hiddenfield "dropDownValue" by JS.

Answer 2

I would reconsider to have one form for each item. One form for all items, including select box, will be enough. So instead of:

<select>...</select>
<form><input type="hidden" name="id" value="1"/><input type="submit" value="Edit"/></form>
<form><input type="hidden" name="id" value="2"/><input type="submit" value="Edit"/></form>

You can have

<form>
    <select>...</select>
    <input type="submit" name="edit:1" value="Edit"/>
    <input type="submit" name="edit:2" value="Edit"/>
</form>

In your servlet, you'll iterate over all request parameters ( request.getParameterNames() ) and look for parameter which starts with edit: prefix. If you find one, just subtrack the prefix and you'll get identifier of your item, which should be otherwise sent in some hidden field. The value of your select box will be sent as well. If you'll need another action, say "delete", you can simply add more submit inputs with different prefix within the same HTML form.