$.ajax如果success却得不到值

在使用$.ajax做异步调用的时候，如果success却得不到值

          $.ajax({
		type:"GET",
		url:tourl,
		cache:false,
		data:"{}",
		success:function(data){
			alert(data);
		}
	});

后台这样写的不到值

         PrintWriter out = ServletActionContext.getResponse().getWriter();
 	out.print(msg);
	out.flush();
	out.close();

如果该改成这样就可以了

         HttpServletResponse response = ServletActionContext.getResponse();
	response.setCharacterEncoding("UTF-8");
	PrintWriter out = response.getWriter();
	out.print(msg);
	out.flush();
	out.close();

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