HttpPost post=new HttpPost(url);
StringEntity content=new StringEntity(data, Charset.forName("utf-8"));// 第二个参数，设置后才会对，内容进行编码
content.setContentType("application/json; charset=UTF-8");
content.setContentEncoding("utf-8");
post.setEntity(content);
原文：http://my.oschina.net/u/1183927/blog/515969