DataSci.main.JsonRequestResponseController.java Source code

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Here is the source code for DataSci.main.JsonRequestResponseController.java

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package DataSci.main;

import java.util.*;
import java.io.*;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.util.*;

public class JsonRequestResponseController {
    // public JSONObject inpParms;
    public String apikey;
    public String apiurl;
    public String jsonBody;

    /**
     * Read the JSON schema from the file rrsJson.json
     * 
     * @param filename It expects a fully qualified file name that contains input JSON file
     */
    public void readJson(String filename) {
        try {
            File apiFile = new File(filename);
            Scanner sc = new Scanner(apiFile);
            jsonBody = "";
            while (sc.hasNext()) {
                jsonBody += sc.nextLine() + "\n";
            }
            sc.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Read the API key and API URL of Azure ML request response REST API
     * 
     * @param filename fully qualified file name that contains API key and API URL
     */
    public void readApiInfo(String filename) {

        try {
            File apiFile = new File(filename);
            Scanner sc = new Scanner(apiFile);

            apiurl = sc.nextLine();
            apikey = sc.nextLine();

            sc.close();
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    /**
     * Call REST API for retrieving prediction from Azure ML 
     * @return response from the REST API
     */
    public String rrsHttpPost() {

        HttpPost post;
        HttpClient client;
        StringEntity entity;

        try {
            // create HttpPost and HttpClient object
            post = new HttpPost(apiurl);
            client = HttpClientBuilder.create().build();

            // setup output message by copying JSON body into 
            // apache StringEntity object along with content type
            entity = new StringEntity(jsonBody/*, HTTP.UTF_8*/);
            // entity.setContentEncoding(HTTP.UTF_8);
            entity.setContentType("text/json");

            // add HTTP headers
            post.setHeader("Accept", "text/json");
            post.setHeader("Accept-Charset", "UTF-8");

            // set Authorization header based on the API key
            post.setHeader("Authorization", ("Bearer " + apikey));
            post.setEntity(entity);

            // Call REST API and retrieve response content
            HttpResponse authResponse = client.execute(post);

            return EntityUtils.toString(authResponse.getEntity());

        } catch (Exception e) {

            return e.toString();
        }

    }

    /**
     * @param args the command line arguments specifying JSON and API info file names
     */
    public void main(String[] args) {
        // check for mandatory arguments. This program expects 2 arguments 
        // first argument is full path with file name of JSON file and 
        // second argument is full path with file name of API file that contains API URL and API Key of request response REST API
        if (args.length < 2) {
            System.out.println("Incorrect arguments");
        }

        try {

            // read JSON file name
            String jsonFile = args[0];
            // read API file name
            String apiFile = args[1];

            // call method to read API URL and key from API file
            readApiInfo(apiFile);

            // call method to read JSON input from the JSON file
            readJson(jsonFile);

            // print the response from REST API
            System.out.println(rrsHttpPost());
        } catch (Exception e) {
            System.out.println(e.toString());
        }
    }

}