$.ajax({
url: "r_getRolePer.action",
dataType:'json', 
data: {userId:"1"}, //请求的附加参数，用json对象
method:'POST',
success: function(data){
$.messager.alert('消息',data.add,'');
//这里使用的时easyui的格式
},
});

public PrintWriter out()throws IOException{
HttpServletResponse response=ServletActionContext.getResponse(); 
    response.setContentType("text/html"); 
    response.setContentType("text/plain; charset=utf-8");
    PrintWriter out= response.getWriter();
    return out;
}
*******
JSONObject permision = new JSONObject();
permision.put("add", 0);
permision.put("delete", 0);
permision.put("update", 0);
out().print(permision.toString());
out().flush();
out().close();