TicketMaster API

HTML request message

Request structure
- GET /doc/test.html HTTP 1.1
  First part indicates the type of the request, second part indicates the resource it asks for, third part is the version of protocal
- Request Header
- Request Body bookId=12345&author=Tan+Ah+Teck
  - Some browser will process the data here.
    - Response structure
- Status line HTTP/1.1 200 OK
  200 indicates that the response status number, and the “OK” is the explanation of the status.
- Response Header
- Response Body <h1>Home page</h1>

RESTful API

CRUD
- Create/Read/Update/Delete
- matches HTTP POST/GET/PUT/DELETE
server is stateless
- No need to involve other requests when handling the request.

TicketMaster API

Request
- URL of discover API protocol://hostname:port/endpoint?query :
  - protocol: https
  - hostname: app.ticketmaster.com
  - endpoint: /discovery/v2/events.json
  - query:
    - APIkey: it’s required by TicketMaster API for authn/authz
    - GeoPoint: lat/long since our search is based on client location
    - Radius: radius of search area
    - Keyword: search a specific kind of events
- example https://app.ticketmaster.com/discovery/v2/events.json?apikey=12345&geoPoint=abcd&keyword=music&radius=50
- Headers and Body: nothing to set since it’s not required for this API.
Response
- data we need is located in _embedded(JSON Object) -> events(JSON Array) -> item object(JSON Object)

Implementation

Create a new Package external in src
Create a new class TicketMasterAPI

Add some constants

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private static final String URL = "https://app.ticketmaster.com/discovery/v2/events.json";
private static final String DEFAULT_KEYWORD = ""; // no restriction
private static final String API_KEY = "USE_YOUR_OWN_KEY";

Add a search function

/**
* Search the keyword through TM API
* @param lat latitude
* @param lon longitude
* @param keyword keyword is optional
*/
public JSONArray search(double lat, double lon, String keyword) {
  return null;
}

Add queryAPI helper

/**
* print the results of search(lat, lon)
* @param lat latitude
* @param lon longitude
*/
private void queryAPI(double lat, double lon) {
  JSONArray events = search(lat, lon, null);
  try {
    for (int i = 0; i < events.length(); i++) {
      JSONObject event = events.getJSONObject(i);
      System.out.println(event);
    }
  } catch (Exception e) {
    e.printStackTrace();
  }
}

Add GeoHash helper to convert lat, lon to geoPoint. Copy the code from http://developer-should-know.com/post/87283491372/geohash-encoding-and-decoding-algorithm

Implement search(lat,lon,keyword) function

/**
* Search the JSONArray results through TM API
* @param lat latitude
* @param lon longitude
* @param keyword keyword is optional
* @return JSONArray
*/
public JSONArray search(double lat, double lon, String keyword) {
  JSONArray ret = new JSONArray();
  if (keyword == null) keyword = DEFAULT_KEYWORD;
  // translate keyword into URL-supported format
  try {
    keyword = java.net.URLEncoder.encode(keyword, "UTF-8");
  } catch (Exception e) {
    e.printStackTrace();
  }
  // Get geoPoint
  String geoHash = GeoHash.encodeGeohash(lat, lon, 8);
  // Create query
  // 50 is default search radius
  String query = String.format("apikey=%s&geoPoint=%s&keyword=%s&radius=%s", API_KEY, geoHash, keyword, 50);
  // Create URL
  try {
    // create a HTTP URL connection
    HttpURLConnection connection = (HttpURLConnection) new URL(URL + "?" + query).openConnection();
    // get the response code EG. 200/success, 404/fail
    int responseCode = connection.getResponseCode();
    // print res
    System.out.println("\nSending \"GET\" request to URL : " + URL + "?" + query);
    System.out.println("\nResponse Code: " + responseCode);
    // check responseCode (Implement it later)
    if (responseCode != 200) {
      
    }
    // read and write the response content
    BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
    String inputLine;
    StringBuilder response = new StringBuilder();
    while ((inputLine = in.readLine()) != null) {
      response.append(inputLine);
    }
    in.close();
    connection.disconnect();
    // write the response to a JSON object
    JSONObject obj = new JSONObject(response.toString());
    // check the result
    if (obj.isNull("_embedded")) {
      return ret;
    }
    // get the events from the whole JSON and return the events field of it as a JSON Array.
    JSONObject embedded = obj.getJSONObject("_embedded");
    JSONArray events = embedded.getJSONArray("events");
    ret = events;
  } catch (Exception e) {
    e.printStackTrace();
  }
  return ret;
}

Create a new package entity and a new class Item(entity表示servelet储存数据的类)

/**
* Item of event
* @author andaluo
*
*/
public class Item {
  private String itemId;
  private String name;
  private double rating;
  private String address;
  private Set<String> categories;
  private String imageURL;
  private String url;
  private double distance;
  
  public JSONObject toJSONObject() {
    JSONObject obj = new JSONObject();
    try {
      obj.put("item_id", itemId);
      obj.put("name", name);	
      obj.put("rating", rating);
      // ...
      } catch (Exception e) {
        e.printStackTrace();
    }
    return obj;
  }

Use builder pattern to create Item class

  /**
  * A helper class to build the Item class
  * @author andaluo
  *
  */
  public static class ItemBuilder{
    private String itemId;
    private String name;
    // ...
    
    /**
    * Construct the Item using builder
    * @return
    */
    public Item build() {
      return new Item(this);
    }
    
    /**
    * return the builder itself to support continuous operation.
    * @param itemId
    * @return
    */
    public ItemBuilder setItemId(String itemId) {
      this.itemId = itemId;
      return this;
    }      
    //...
  }

  /**
  * Builder pattern to create a class
  * @param builder
  */
  public Item(ItemBuilder builder) {
    this.itemId = builder.itemId;
    this.name = builder.name;
    // ...

  // when build the item we get
  public static void main(String[] args) {
Item item = new Item.ItemBuilder().setAddress("abc").setDistance(19).build();
  }