如何在java中的http post中發送json對象

Question

我想發送一個JSON對象（注意它不應該轉換成字符串，因為服務器端代碼基於Spring啟動項目並且有params（@RequestBody PCAP pcap））我有我的下面的代碼，但它轉換為正文成為一個字符串，給我400個不良請求。

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：服務器端代碼是

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

Answer 1

我更喜歡在HttpClient上繼續使用HttpURLConnection。 在SE問題中可以找到一些關於優勢的評論

output.write(json.toString());

應改為

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

寫入對象后不要忘記調用flush（），並且在寫入操作之前應該指示UTF-8格式。