无法通过java发布请求获得成功，但能够使用邮递员获得成功

Question

Java代码：

public class KeyGeneration {

    public static void main(String[] args) throws Exception {
        System.out.println("Send Http POST request");
        sendPost();
    }

    // HTTP POST request
    private static void sendPost() throws Exception {

        String url = "http://localhost:4000/channels/mychannel/chaincodes/changedneww741";
        URL obj = new URL(url);
        HttpURLConnection con = (HttpURLConnection) obj.openConnection();

        //add request header
        con.setRequestMethod("POST");
        con.setRequestProperty("Content-Type","application/json");
        con.setRequestProperty("Authorization","Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE1MTY3MjE4MDgsInVzZXJuYW1lIjoiSmltIiwib3JnTmFtZSI6Im9yZzEiLCJpYXQiOjE1MTY2ODU4MDh9.8iUCGNaLYhC6MFPfnvc9lxk9b9Oi-5OtwLYgF7Pn6a8");


        String urlParameters = "peers=[\"localhost:7051\",\"localhost:8051\"]&fcn=move&args=[\"publickey\",\"raj1242\"]";

        // Send post request
        con.setDoOutput(true);
        DataOutputStream wr = new DataOutputStream(con.getOutputStream());
        wr.writeBytes(urlParameters);
        wr.flush();
        wr.close();

        int responseCode = con.getResponseCode();
        System.out.println("\nSending 'POST' request to URL : " + url);
        System.out.println("Post parameters : " + urlParameters);
        System.out.println("Response Code : " + responseCode);

        BufferedReader in = new BufferedReader(
                new InputStreamReader(con.getInputStream()));
        String inputLine;
        StringBuffer response = new StringBuffer();

        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();

        //print result
        System.out.println(response.toString());

    }

}

错误：

  

java.io.IOException：服务器返回HTTP响应代码：400为URL：   http://localhost:4000/channels/mychannel/chaincodes/changedneww741 at   sun.reflect.NativeConstructorAccessorImpl.newInstance0（本机方法）     在   sun.reflect.NativeConstructorAccessorImpl.newInstance（NativeConstructorAccessorImpl.java:62）     在   sun.reflect.DelegatingConstructorAccessorImpl.newInstance（DelegatingConstructorAccessorImpl.java:45）     at java.lang.reflect.Constructor.newInstance（Constructor.java:423）     在   sun.net.www.protocol.http.HttpURLConnection $ 10.run（HttpURLConnection.java:1926）     在   sun.net.www.protocol.http.HttpURLConnection $ 10.run（HttpURLConnection.java:1921）     在java.security.AccessController.doPrivileged（Native Method）at   sun.net.www.protocol.http.HttpURLConnection.getChainedException（HttpURLConnection.java:1920）     在   sun.net.www.protocol.http.HttpURLConnection.getInputStream0（HttpURLConnection.java:1490）     在   sun.net.www.protocol.http.HttpURLConnection.getInputStream（HttpURLConnection.java:1474）     在mailsend.KeyGeneration.sendPost（KeyGeneration.java:131）at   mailsend.KeyGeneration.main（KeyGeneration.java:35）引起：   java.io.IOException：服务器返回HTTP响应代码：400为URL：   http://localhost:4000/channels/mychannel/chaincodes/changedneww741 at   sun.net.www.protocol.http.HttpURLConnection.getInputStream0（HttpURLConnection.java:1876）     在   sun.net.www.protocol.http.HttpURLConnection.getInputStream（HttpURLConnection.java:1474）     在   java.net.HttpURLConnection.getResponseCode（HttpURLConnection.java:480）     在mailsend.KeyGeneration.sendPost（KeyGeneration.java:125）... 1   更