I'm working with New Relic REST API for the first time, I have a curl command:
curl -X GET 'https://api.newrelic.com/v2/applications/appid/metrics/data.json' \
-H 'X-Api-Key:myApiKey' -i \
-d 'names[]=EndUser/WebTransaction/WebTransaction/JSP/index.jsp'
I want to send this command in a java servlet and get a JSON object from the response ready for parsing, What is the best solution?
HttpURLConnection?
Apache httpclient?
I've tried a few different solutions, but nothing has worked so far and most examples I could find are using the depreciated DefaultHttpClient
Here is an example of one of my attempts:
String url = "https://api.newrelic.com/v2/applications.json";
HttpURLConnection conn = (HttpURLConnection) new URL(url).openConnection();
conn.setRequestProperty("Content-Type", "application/json");
conn.setRequestProperty("X-Api-Key", "myApiKey");
conn.setRequestMethod("GET");
JSONObject names =new JSONObject();
try {
names.put("names[]=", "EndUser/WebTransaction/WebTransaction/JSP/index.jsp");
} catch (JSONException e) {
e.printStackTrace();
}
OutputStreamWriter wr= new OutputStreamWriter(conn.getOutputStream());
wr.write(names.toString());
Edit
I've modified the code a bit, it's working now thanks.
String names = "names[]=EndUser/WebTransaction/WebTransaction/JSP/index.jsp";
String url = "https://api.newrelic.com/v2/applications/myAppId/metrics/data.json";
String line;
try (PrintWriter writer = response.getWriter()) {
HttpURLConnection conn = (HttpURLConnection) new URL(url).openConnection();
conn.setRequestProperty("Accept", "application/json");
conn.setRequestProperty("X-Api-Key", "myApiKey");
conn.setRequestMethod("GET");
conn.setDoOutput(true);
conn.setDoInput(true);
OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());
wr.write(names);
wr.flush();
BufferedReader reader = new BufferedReader(new
InputStreamReader(conn.getInputStream()));
while ((line = reader.readLine()) != null) {
System.out.println(line);
writer.println(HTML_START + "<h2> NewRelic JSON Response:</h2><h3>" + line + "</h3>" + HTML_END);
}
wr.close();
reader.close();
}catch(MalformedURLException e){
e.printStackTrace();
}
curl -d sends whatever you specify without formatting it in any way. Just send the string names[]=EndUser/... in the OutputStream, without wrapping it in a JSONObject. Don't forget to call wr.flush() after writing the string. And of course, after that, you need to get the InputStream and start reading from it (I only mention this because it's not in your snippet).
Related
I am trying to send a POST (with XML in the body) to an API and get a response back that is XML. There are confirmation or error details that I need to get from the response body (from within the ERRORelement).
I can send the POST and it does trigger the change in the API, but I cannot read the response.
When I send the POST manually from Postman, I trigger the change in the API and I can see the response from the API as text/html;charset=charset=utf-8
Here is my current code:
URL url = new URL(urlString);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setDoOutput(true);
OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream());
writer.write(xmlString);
writer.flush();
String line;
BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
writer.close();
reader.close();
The response body should be in the following format:
<Root>
<Session>
<UserId>theUserID</UserId>
<Password>thePassword</Password>
<ERROR Status="0" Description="Logon Successful" />
</Session>
<ActivityList>
<Activity Type="ReqUp" Incident="12345" ElapsedTime="350"
Description="example response"
Status="Complete">
<ERROR Status="0" Description="OK" />
</Activity>
</ActivityList>
</Root>
Current/Actual result:
line is showing as null
Since you want xml to come back from the server, it is likely that you need to add an "accept" header to the request to tell the server that you (the client) will "accept" xml. From your post, it appears that the default is html.
This might work for you:
URL url = new URL(urlString);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestProperty("accept", "application/xml");
conn.setDoOutput(true);
OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream());
If you are sending xml to the server, you also may want to add a "content-type" header, like this:
conn.setRequestProperty("content-type", "application/xml");
ref: https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
There was a bug in my original code that prevented line from ever forming anything other than null.
the correct code is as follows:
URL url = new URL(urlString);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestProperty("accept", "text/html");
conn.setDoOutput(true);
OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream());
writer.write(xmlString);
writer.flush();
String builtResponse = "";
String line ="";
BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
while ((line = reader.readLine()) != null) {
builtResponse += line;
}
writer.close();
reader.close();
My program below stopped at the line:
InputStream is = conn.getInputStream();
Neither error message popped up nor any output displayed on the console.
I am running Eclipse Oxygen 4.7.0 on Red Hat Enterprise Linux Server release 7.4.
public static void solveInstance(String instanceName){
// solve a problem instance
try{
String query_url = "http://localhost:8807/scheduler";
// read Request to a JSON Object
JSONParser parser = new JSONParser();
JSONObject request = (JSONObject) parser.parse(new FileReader(instanceName));
// open connection
URL url = new URL(query_url);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setConnectTimeout(5000);
conn.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
conn.setDoOutput(true);
conn.setRequestMethod("POST");
// POST Request
OutputStream os = conn.getOutputStream();
OutputStreamWriter osw = new OutputStreamWriter(os, "UTF-8");
osw.write(request.toString());
osw.close();
// Get Response
InputStream is = conn.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader in = new BufferedReader(isr);
String inputLine;
StringBuffer response = new StringBuffer();
while(( inputLine = in.readLine()) != null )
{
response.append(inputLine);
}
in.close();
// Write response to a file
JSONObject jsonObj = (JSONObject) parser.parse(response.toString());
String responseFile = /path_to_result/result.json;
FileWriter fileWriter = new FileWriter(responseFile);
fileWriter.write(jsonObj.toString());
fileWriter.flush();
fileWriter.close();
System.out.println("Solved" + instanceName);
}
catch(Exception e) {
System.out.println(e);
}
}
I noticed that the similar question is asked InputStream is = httpURLConnection.getInputStream(); stop working
but it was for Android and no solution was given there.
Does anyone have some idea on that? Do not hesitate to point out anything else wrong in my code.
Thanks a lot!
Your server isn't responding.
It would be wise to set a read timeout, with conn.setReadTimeout(5000) (say). Adjust the timeout as necessary.
Check response code
int response = connection.getResponseCode();
If you get 301 it means that your resource is redirected. Try to change URI from http to https.
It helped in my case.
I want to implement the code for handling POST requests using try with resources.
Following is my code:
public static String sendPostRequestDummy(String url, String queryString) {
log.info("Sending 'POST' request to URL : " + url);
log.info("Data : " + queryString);
BufferedReader in = null;
HttpURLConnection con = null;
StringBuilder response = new StringBuilder();
try{
URL obj = new URL(url);
con = (HttpURLConnection) obj.openConnection();
// add request header
con.setRequestMethod("POST");
con.setRequestProperty("User-Agent", "Mozilla/5.0");
con.setRequestProperty("Accept-Language", "en-US,en;q=0.5");
con.setRequestProperty("Content-Type", "application/json");
// Send post request
con.setDoOutput(true);
DataOutputStream wr = new DataOutputStream(con.getOutputStream());
wr.writeBytes(queryString);
wr.flush();
wr.close();
int responseCode = con.getResponseCode();
log.info("Response Code : " + responseCode);
if (responseCode >= 400)
in = new BufferedReader(new InputStreamReader(con.getErrorStream()));
else
in = new BufferedReader(new InputStreamReader(con.getInputStream()));
String inputLine;
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
}catch(Exception e){
log.error(e.getMessage(), e);
log.error("Error during posting request");
}
finally{
closeConnectionNoException(in,con);
}
return response.toString();
}
I have the following concerns for the code:
How to introduce conditional statements in try with resources for the above scenario?
Is there a way to pass on the connection in try with resources? (It can be done using nested try-catch blocks since URL and HTTPConnection is not AutoCloseable, which itself is not a compliant solution)
Is using try with resources for the above problem is a better approach?
Try this.
HttpURLConnection con = (HttpURLConnection) obj.openConnection();
try (AutoCloseable conc = () -> con.disconnect()) {
// add request headers
try (DataOutputStream wr = new DataOutputStream(con.getOutputStream())) {
wr.writeBytes(queryString);
}
int responseCode = con.getResponseCode();
try (InputStream ins = responseCode >= 400 ? con.getErrorStream() : con.getInputStream();
BufferedReader in = new BufferedReader(new InputStreamReader(ins))) {
// receive response
}
}
() -> con.disconnect() is a lambda expression which execute con.disconnect() at finally stage of the try statement.
1: You can use conditional statements inside try with resources statement also. Unfortunately you have to define new variable for this block and cannot use a predefined variable. ( variable in in your code)
try (BufferedReader in = (responseCode >= 400 ? new BufferedReader(new InputStreamReader(con.getErrorStream())) : new BufferedReader(new InputStreamReader(con.getInputStream())))) {
// your code for getting string data
}
2: I'm not sure HttpUrlConnection is AutoCloseable, So it might be a good idea to call the disconnect() yourself. I'm open to any suggestion on this one.
3: try with resources will definitely help you in managing the resources. But if you're confident that you're releasing the resources properly after use, then your code is fine.
I have written a Java Code to test the Watson Question and Answers API. However, I'm getting response code 500, when I run it. I have checked the api url and my login credentials. The problem seems to be somewhere else. Any hints or debugging suggestions would be of great help.
String url = "https://watson-wdc01.ihost.com/instance/526/deepqa/v1/question";
URL obj = new URL(url);
HttpsURLConnection con = (HttpsURLConnection) obj.openConnection();
//add reuqest header
String userCredentials = "username:password";
String basicAuth = "Basic " + DatatypeConverter.printBase64Binary(userCredentials.getBytes());
con.setRequestProperty ("Authorization", basicAuth);
con.setRequestProperty("X-SyncTimeout", "30");
con.setRequestProperty("Accept", "application/json");
con.setRequestProperty("Content-Type", "application/json");
con.setRequestProperty("Cache-Control", "no-cache");
con.setRequestMethod("POST");
String query = "{\"question\": {\"questionText\": \"" + "What are the common respiratory diseases?" + "\"}}";
System.out.println(query);
// Send post request
con.setDoOutput(true);
DataOutputStream wr = new DataOutputStream(con.getOutputStream());
wr.writeBytes(query);
wr.flush();
wr.close();
int responseCode = con.getResponseCode();
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());
When i open the same url with the browser I get this:
Watson Error!!
Error Encountered!!
Unable to communicate with Watson.
Whats wrong? Could it be something with the configuration? Or is the server down?
Any hints or debugging suggestions would be of great help.
Attempt the same request using your web browser ... or the curl utility.
Capture and output the contents of the error stream.
I don't think that this is the cause of your problems, but it is wrong anyway:
DataOutputStream wr = new DataOutputStream(con.getOutputStream());
wr.writeBytes(query);
wr.flush();
You are writing to an API that expects text (JSON). You should therefore use a Writer, not a data (binary) output stream:
Writer wr = new OutputStreamWriter(con.getOutputStream(), "LATIN-1");
wr.write(query);
wr.flush();
I am sending json string in an https post request to an apache servert(request sends json data to a cgi-bin script that actually is a python script). Am using a standard cgi call -
f=open("./testfile", "w+")
f.write("usageData json = \n")
<b>form = cgi.FieldStorage()
formList = ['Data']
str = form['Data'].value
str = json.dumps(backupstr)
</b>
print backupstr
to read the json string in the url. Problem is that the script is not reading the json in the url even though the script is getting fired (the basic print statements are executing ...). This is how am sending data from the post side :
HttpsURLConnection connection = null;
try{
connection = (HttpsURLConnection)url.openConnection();
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type",
"application/json");
connection.setRequestProperty("Content-Length", "" +
Integer.toString(jsonstring.getBytes().length));
connection.setRequestProperty("Content-Language", "en-US");
connection.setUseCaches (false);
connection.setDoInput(true);
connection.setDoOutput(true);
//Send request
DataOutputStream wr = new DataOutputStream (
connection.getOutputStream ());
//wr.writeBytes(jsonstring);
wr.writeUTF(URLEncoder.encode(jsonstring, "UTF-8"));
wr.flush ();
wr.close ();
//Get Response
InputStream is = connection.getInputStream();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
String line;
StringBuffer response = new StringBuffer();
while((line = rd.readLine()) != null) {
response.append(line);
}
rd.close();
//response = httpClient.execute(request);
}
catch (Exception e)
{
System.out.println("Exception " + e.getMessage());
throw e;
}
I suspect am missing one or more of the connection.setRequestProperty() settings on the sending end that's why it's firing the script but not reading the json string in the url ...what am I doing wrong ...?