如何用java在http post中发送json对象

Question

我想发送一个JSON对象（注意，它不应该转换成字符串，因为服务器端代码是基于Spring starter项目的，它的params为(@requestbody PCAP PCAP））我有下面的代码，但它将主体转换成一个字符串，这给了我400个错误的请求。

private void sendData(String ip){
    try{
        JSONObject json=new JSONObject();
        json.put("time_range", "22-23");
        json.put("flow_id", "786");
        json.put("ip_a", "192.65.78.22");
        json.put("port_a", "8080");
        json.put("regex", "%ab");



        URL url=new URL("http://"+ip+":8080/pcap");
        HttpURLConnection httpcon=(HttpURLConnection)url.openConnection();
        httpcon.setDoOutput(true);
        httpcon.setRequestMethod("POST");
        httpcon.setRequestProperty("Accept", "application/json");
        httpcon.setRequestProperty("Content-Type", "application/json");
        Cookie cookie=new Cookie("user", "abc");
        cookie.setValue("store");
        httpcon.setRequestProperty("Accept", "application/json");
        httpcon.setRequestProperty("Cookie", cookie.getValue());

        OutputStreamWriter output=new OutputStreamWriter(httpcon.getOutputStream());
        System.out.println(json);
        output.write(json.toString());
        httpcon.connect();
        String output1=httpcon.getResponseMessage();
        System.out.println(output1);

    }catch(Exception e){

    }

}

注意：服务器端代码为

@RequestMapping(value = URIConstansts.PCAP, produces = { "application/json" }, method = RequestMethod.POST)
    public  ResponseEntity getPcap(HttpServletRequest request,@RequestBody PcapParameters pcap_params )

Answer 1

我更喜欢继续使用HttpURLConnection而不是HttpClient。在这个问题上可以找到一些关于优势的评论

output.write(json.tostring())；

应更改为

byte[] jsonBytes = json.getBytes("UTF-8");
output.write(jsonBytes);
output.flush();