Executing curl command in java application

Question

I am trying to execute a curl command (which works in the terminal) through my java application. I have tried using a process Builder as well as a Runtime.exec(). I am able to connect, but the response either says

{"result":0,"reason":"Unknown Json request format"}

or

{"result":0,"reason":"Invalid client request Json string"}.

Here is the curl command that works in the terminal:

curl -X POST -d '{"command":"get","user":"R16","id":5552}' "http://<Ex.webaddress>"

When running this, the connection fails

String testCurlCommand = "curl -X POST -d '{\"command\":\"get\",\"user\":\"R16\",\"id\":5552}' \"http://<Ex.webaddress\"";try {
        //final Process terminal = curlCommand.start();
        Process p = Runtime.getRuntime().exec(testCurlCommand);
        try {
            String responseString = readInputStream(p.getInputStream());
            JSONObject job = new JSONObject(responseString);

            // job.getString("Parameter")
            statusLabel.setText("Command Result: " + job.toString());
            connectionStatusLabel.setText("Connection Status: Successful");
        } catch (JSONException e) {
            statusLabel.setText("Command Result: 0");
            connectionStatusLabel.setText("Connection Status: Failed");
        }
    } catch (IOException ex) {
        statusLabel.setText("Command Result: 0");
        connectionStatusLabel.setText("Connection Status: Failed");
    }

When changing the String testCurlCommand by removing the quotes around the web address, the connection works but I get the "unknown Json request format"

String testCurlCommand = "curl -X POST -d '{\"command\":\"get\",\"user\":\"R16\",\"id\":5552}' http://<Ex.webaddress";

Ive tried removing the escaped quotes and I still get the same. Ive also tried with process builder:

ProcessBuilder testCurlCommand = new ProcessBuilder("curl", "-X", "POST", "-d", "'{\"command\":\"get\",\"user\":\"R16\",\"id\":\"5552\"}'", "\"http://<examplewebaddress>\"")

I think its something to do with the formating (extra quote or something) but I'm not sure. Any help is greatly appreciated.I will add the readInputStream function below:

static private String readInputStream(InputStream inputStream) throws IOException {
    BufferedReader reader = new BufferedReader(new InputStreamReader(
            inputStream, "UTF-8"));
    String tmp;
    StringBuilder sb = new StringBuilder();
    while ((tmp = reader.readLine()) != null) {
        sb.append(tmp).append("\n");
    }
    if (sb.length() > 0 && sb.charAt(sb.length() - 1) == '\n') {
        sb.setLength(sb.length() - 1);
    }
    reader.close();
    return sb.toString();
}

Why don't you do your POST directly with Java instead? I would be much simpler so easier to maintain and cross-platform — Nicolas Filotto
– Nicolas Filotto, Commented Jun 1, 2016 at 15:42
Im not sure on how to do that, do you have any links I should visit? Thank you — B.minnick
– B.minnick, Commented Jun 1, 2016 at 15:46

Rick · Accepted Answer · 2016-06-01 15:49:00Z

1

For me this looks like a quotation mark issue. Try to be consistent and try to escape the following quotation marks with backslashes

curl -X POST -d '{"command":"get","user":"R16","id":5552}' 'http://<Ex.webaddress>'

PS: I just changed the url quotation marks from " to '

answered Jun 1, 2016 at 15:49

Rick

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Nicolas Filotto · Accepted Answer · 2016-06-01 15:49:53Z

1

The best way I know is with DavidWebb.

You could do it with something like:

Response<JSONObject> result = Webb.create().post("http://<Ex.webaddress>")
        .body("{\"command\":\"get\",\"user\":\"R16\",\"id\":5552}").asJsonObject();
JSONObject job = result.getBody();

answered Jun 1, 2016 at 15:49

Nicolas Filotto

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2 Comments

B.minnick Over a year ago

Thank you! Also what do I need to import? I downloaded the David Webb jar file and added it to the library.

Nicolas Filotto Over a year ago

you need this mvnrepository.com/artifact/org.json/json/20080701 as you can see here github.com/hgoebl/DavidWebb/blob/master/pom.xml#L26-L30

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