var BuildPostForm = function(formName,params,action,target){
    if(formName==null){ return null;}
    var form = document.getElementById(formName);
    if(!form){
        form = document.createElement("form");
        form.id = formName;
        document.body.appendChild(form);
    }
    if(action!=null){ form.action = action; }
    if(target!=null){ form.target = target; }
    form.method = "post";
    form.style.display = "none";
    form.enctype = "application/x-www-form-urlencoded"; 
    form.acceptCharset="GB2312"; //非IE
    var tempInnerHTML = new StringBuilder();
    if(typeof(params)=="object"){       
        for(var name in params){
			tempInnerHTML.append("<input type=\"hidden\" name=\"");
			tempInnerHTML.append(name);
			tempInnerHTML.append("\" value=\"");
			tempInnerHTML.append(params[name]);
			tempInnerHTML.append("\" />");        
        }
    }else{
        tempInnerHTML.append("<input type=\"hidden\" name=\"param\" value\"");
		tempInnerHTML.append(params);
		tempInnerHTML.append("\" />");
    }
    try{ form.innerHTML=tempInnerHTML.ToString();}
    catch(e){ return null;}
    return form;
}