不写死任何东西，借助jquery ajax提交Dedecms自定义表单到后台。

注意表单部分，此例只做为参考，实际项目中根据自己的情况酌情修改。

<form action="/plus/diy.PHP" enctype="multipart/form-data" method="post" id="diyform">
<input type="hidden" name="action" value="post" />
<input type="hidden" name="diyid" value="1" />
<input type="hidden" name="do" value="2" />
<input type="hidden" name="dede_fields" value="mail_name,text;mail_phone;mail_content,multitext" />
<input type="hidden" name="dede_fieldshash" value="86d34525cf75f8652022f6446152028d" />
<input type="hidden" name="setup" value="ajax" /><!-- 这是为了跟其他非ajax自定义表单不冲突 -->
    <div class="mail_rdd">
        <div class="mail_content">
            <table border="1" width="100%" class="mail_form">
            <tr>
                <td width="50">
                    姓名：
                </td>
                <td class="mail_input_bg1">
                    <input type="text" name="mail_name" id="mail_name" maxlength="20"/>
                </td>
            </tr>
            <tr>
                <td>
                    电话：
                </td>
                <td class="mail_input_bg1">
                    <input type="text" name="mail_phone" id="mail_phone" maxlength="20"/>
                </td>
            </tr>
            <tr style="height:240px">
                <td>
                    留言：
                </td>
                <td class="mail_input_bg3">
                    <textarea name="mail_content" id="mail_content"></textarea>
                </td>
            </tr>
            </table>
            <div class="mail_button_bar">
                <div class="mail_button confirm" onclick="send()">
                </div>
            </div>
        </div>
    </div>
</form>

js ajax方法部分

<script type="text/javascript" src="http://apps.bdimg.com/libs/jquery/1.6.4/jquery.min.js"></script>
<script>
function send(){
    $.ajax({
        cache: true,type: "POST",url:"/plus/diy.PHP",data:$('#diyform').serialize(),// 你的form里面的id
        success: function(data) {
            if(data=="success"){
                alert('发送成功!');
            }else{
                alert('发送失败!');
            }
        }
    });
}
</script>

打开/plus/diy.PHP 找到

showmsg($bkmsg,$goto);

改成

if($setup == 'ajax') { echo "success"; exit; } else { showmsg($bkmsg,$goto); }

如果是gbk编码的童鞋，还要修改/plus/diy.PHP，解决乱码问题

打开/plus/diy.PHP 找到

$addvalue .= ",'".${$fieldinfo[0]}."'";

改成

$addvalue .= ",'".iconv( "UTF-8","gb2312//IGNORE",${$fieldinfo[0]})."'";

另一种js $.post方法

var dataString = {
	'name':$("#name").val(),'tel':$("#tel").val(),'setup':'ajax','action':'post','diyid':1,'do':2,'dede_fields':'name,text;tel,text','dede_fieldshash':'6b5fb808a4b9ea6d0603d983246a88a1',};
$.post("/plus/diy.PHP",dataString,function(result){
	if(result=="1"){
		alert('发送成功!');
		$('#diyform').reset();//重置form
	}else{
		alert('发送失败!');
	}
});