[FIXED] Getting JSON response as part of Rest call in Java

Issue

I am trying to make Rest service call in Java. I am new to web and Rest service. I have Rest service which returns JSON as response. I have the following code but I think it's incomplete because I don't know how to process output using JSON.

public static void main(String[] args) {
        try { 
            
            URL url = new URL("http://example.com:7000/test/db-api/processor"); 
            HttpURLConnection connection = (HttpURLConnection) url.openConnection(); 
            connection.setDoOutput(true); 
            connection.setInstanceFollowRedirects(false); 
            connection.setRequestMethod("PUT"); 
            connection.setRequestProperty("Content-Type", "application/json"); 

            OutputStream os = connection.getOutputStream(); 
           //how do I get json object and print it as string
            os.flush(); 

            connection.getResponseCode(); 
            connection.disconnect(); 
        } catch(Exception e) { 
            throw new RuntimeException(e); 
        } 

    }

I am new to Rest services and JSON.

Solution

Since this is a PUT request you're missing a few things here:

OutputStream os = conn.getOutputStream();
os.write(input.getBytes()); // The input you need to pass to the webservice
os.flush();
...
BufferedReader br = new BufferedReader(new InputStreamReader(
        (conn.getInputStream()))); // Getting the response from the webservice

String output;
System.out.println("Output from Server .... \n");
while ((output = br.readLine()) != null) {
    System.out.println(output); // Instead of this, you could append all your response to a StringBuffer and use `toString()` to get the entire JSON response as a String.
    // This string json response can be parsed using any json library. Eg. GSON from Google.
}

Have a look at this to have a more clear idea on hitting webservices.

Answered By - Rahul
Answer Checked By - Cary Denson (JavaFixing Admin)