curl Post Json
$ curl -i -X POST -H "'Content-type':'application/x-www-form-urlencoded', 'charset':'utf-8', 'Accept': 'text/plain'" -d 'json_data={"a":"aaa","b":"bbb","data":[{"c":"ccc","d":"ddd","keywords":[{"e": "eee", "f":"fff", "g":"ggg"}]}]}' url

返回信息：

HTTP/1.1 200 OK

Server: Apache-Coyote/1.1

Set-Cookie: JSESSIONID=02565379F21852B33D0367FB7982FE1C; Path=/; HttpOnly

Content-Type: application/json;charset=UTF-8

Transfer-Encoding: chunked

Date: Tue, 22 Oct 2013 10:48:24 GMT

这里想要post Json数据到接口上，需要设置好Header，也就是：'Content-type':'application/x-www-form-urlencoded', 'charset':'utf-8', 'Accept': 'text/plain'。
之前一直认为是设置好Content-Type=application/json即可，但是如果有中文就会遇到需要encode的地方了。