Issue #8 - Extract consts in a dedicated file

Author: Anthony Roux

src/main/java/com/amadeus/Constants.java

@@ -0,0 +1,48 @@
+package com.amadeus;
+
+/**
+ * A class for constant variables
+ *
+ * <pre>
+ *  To use: Constants.VARIABLE
+ * </pre>
+ */
+
+public final class Constants {
+  // HTTP verbs
+  public static final String GET = "GET";
+  public static final String POST = "POST";
+
+  public static final String HTTPS = "https";
+  public static final String HTTP = "http";
+
+  public static final String USER_AGENT = "User-Agent";
+  public static final String ACCEPT = "Accept";
+  public static final String AUTHORIZATION = "Authorization";
+  public static final String CONTENT_TYPE = "Content-Type";
+
+  // Pagination
+  public static final String FIRST = "first";
+  public static final String LAST = "last";
+  public static final String NEXT = "next";
+  public static final String PREVIOUS = "previous";
+
+  // Authorization
+  public static final String GRANT_TYPE = "grant_type";
+  public static final String CLIENT_CREDENTIALS = "client_credentials";
+  public static final String CLIENT_ID = "client_id";
+  public static final String CLIENT_SECRET = "client_secret";
+  public static final String AUTH_URL = "/v1/security/oauth2/token";
+  public static final String ACCESS_TOKEN = "access_token";
+  public static final String EXPIRES_IN = "expires_in";
+
+
+  /**
+   * The caller references the constants using <tt>Consts.EMPTY_STRING</tt>,
+   * and so on. Thus, the caller should be prevented from constructing objects of
+   * this class, by declaring this private constructor.
+   */
+  private Constants() {
+    throw new AssertionError();
+  }
+}

src/main/java/com/amadeus/HTTPClient.java

@@ -1,5 +1,6 @@
 package com.amadeus;
 
+import com.amadeus.Constants;
 import com.amadeus.client.AccessToken;
 import com.amadeus.exceptions.NetworkException;
 import com.amadeus.exceptions.ResponseException;
@@ -35,7 +36,7 @@ protected HTTPClient(Configuration configuration) {
    * @see Amadeus#get(String, Params)
    */
   public Response get(String path) throws ResponseException {
-    return request("GET", path, null);
+    return request(Constants.GET, path, null);
   }
 
   /**
@@ -62,7 +63,7 @@ public Response get(String path) throws ResponseException {
    * @return a Response object containing the status code, body, and parsed data.
    */
   public Response get(String path, Params params) throws ResponseException {
-    return request("GET", path, params);
+    return request(Constants.GET, path, params);
   }
 
   /**
@@ -72,7 +73,7 @@ public Response get(String path, Params params) throws ResponseException {
    * @see Amadeus#post(String, Params)
    */
   public Response post(String path) throws ResponseException {
-    return request("POST", path, null);
+    return request(Constants.POST, path, null);
   }
 
   /**
@@ -99,7 +100,7 @@ public Response post(String path) throws ResponseException {
    * @return a Response object containing the status code, body, and parsed data.
    */
   public Response post(String path, Params params) throws ResponseException {
-    return request("POST", path, params);
+    return request(Constants.POST, path, params);
   }
 
   /**
@@ -123,7 +124,7 @@ public Response unauthenticatedRequest(String verb, String path, Params params,
    * @throws ResponseException if the page could not be found
    */
   public Response previous(Response response) throws ResponseException {
-    return page("previous", response);
+    return page(Constants.PREVIOUS, response);
   }
 
   /**
@@ -133,7 +134,7 @@ public Response previous(Response response) throws ResponseException {
    * @throws ResponseException if the page could not be found
    */
   public Resource[] previous(Resource resource) throws ResponseException {
-    return page("previous", resource);
+    return page(Constants.PREVIOUS, resource);
   }
 
   /**
@@ -143,7 +144,7 @@ public Resource[] previous(Resource resource) throws ResponseException {
    * @throws ResponseException if the page could not be found
    */
   public Response next(Response response) throws ResponseException {
-    return page("next", response);
+    return page(Constants.NEXT, response);
   }
 
   /**
@@ -153,7 +154,7 @@ public Response next(Response response) throws ResponseException {
    * @throws ResponseException if the page could not be found
    */
   public Resource[] next(Resource resource) throws ResponseException {
-    return page("next", resource);
+    return page(Constants.NEXT, resource);
   }
 
   /**
@@ -163,7 +164,7 @@ public Resource[] next(Resource resource) throws ResponseException {
    * @throws ResponseException if the page could not be found
    */
   public Response first(Response response) throws ResponseException {
-    return page("first", response);
+    return page(Constants.FIRST, response);
   }
 
   /**
@@ -173,7 +174,7 @@ public Response first(Response response) throws ResponseException {
    * @throws ResponseException if the page could not be found
    */
   public Resource[] first(Resource resource) throws ResponseException {
-    return page("first", resource);
+    return page(Constants.FIRST, resource);
   }
 
   /**
@@ -183,7 +184,7 @@ public Resource[] first(Resource resource) throws ResponseException {
    * @throws ResponseException if the page could not be found
    */
   public Response last(Response response) throws ResponseException {
-    return page("last", response);
+    return page(Constants.LAST, response);
   }
 
   /**
@@ -193,7 +194,7 @@ public Response last(Response response) throws ResponseException {
    * @throws ResponseException if the page could not be found
    */
   public Resource[] last(Resource resource) throws ResponseException {
-    return page("last", resource);
+    return page(Constants.LAST, resource);
   }
 
   // A generic method for making requests of any verb.
@@ -237,7 +238,7 @@ private Request fetch(Request request) throws NetworkException {
 
   // Writes the parameters to the request.
   private void write(Request request) throws IOException {
-    if (request.getVerb() == "POST" && request.getParams() != null) {
+    if (request.getVerb() == Constants.POST && request.getParams() != null) {
       OutputStream os = request.getConnection().getOutputStream();
       BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(os, "UTF-8"));
       writer.write(request.getParams().toQueryString());

src/main/java/com/amadeus/Request.java

@@ -1,5 +1,7 @@
 package com.amadeus;
 
+import com.amadeus.Constants;
+
 import java.io.IOException;
 import java.net.HttpURLConnection;
 import java.net.URL;
@@ -112,7 +114,7 @@ protected void establishConnection() throws IOException {
 
   // Determines the scheme based on the SSL value
   private void determineScheme() {
-    this.scheme = isSsl() ? "https" : "http";
+    this.scheme = isSsl() ? Constants.HTTPS : Constants.HTTP;
   }
 
   // Prepares the full URL based on the scheme, host, port and path.
@@ -124,10 +126,10 @@ private void prepareUrl() {
   // Prepares the headers to be sent in the request
   private void prepareHeaders() {
     this.headers = new HashMap<String, String>();
-    headers.put("User-Agent", buildUserAgent());
-    headers.put("Accept", "application/json, application/vnd.amadeus+json");
+    headers.put(Constants.USER_AGENT, buildUserAgent());
+    headers.put(Constants.ACCEPT, "application/json, application/vnd.amadeus+json");
     if (bearerToken != null) {
-      headers.put("Authorization", bearerToken);
+      headers.put(Constants.AUTHORIZATION, bearerToken);
     }
   }
 
@@ -144,7 +146,7 @@ private String buildUserAgent() {
 
   // Gets the serialized params, only if this is a Get call
   private String getQueryParams() {
-    if (verb == "GET" && params != null) {
+    if (verb == Constants.GET && params != null) {
       return params.toQueryString();
     } else {
       return "";

src/main/java/com/amadeus/Response.java

@@ -1,5 +1,6 @@
 package com.amadeus;
 
+import com.amadeus.Constants;
 import com.amadeus.exceptions.AuthenticationException;
 import com.amadeus.exceptions.ClientException;
 import com.amadeus.exceptions.NotFoundException;
@@ -152,7 +153,7 @@ private boolean isJson() {
 
   // Checks if the response headers include a JSON mime-type.
   private boolean hasJsonHeader() {
-    String contentType = getRequest().getConnection().getHeaderField("Content-Type");
+    String contentType = getRequest().getConnection().getHeaderField(Constants.CONTENT_TYPE);
     String[] expectedContentTypes = new String[] {
       "application/json", "application/vnd.amadeus+json"
     };

src/main/java/com/amadeus/client/AccessToken.java

@@ -1,6 +1,7 @@
 package com.amadeus.client;
 
 import com.amadeus.Configuration;
+import com.amadeus.Constants;
 import com.amadeus.HTTPClient;
 import com.amadeus.Params;
 import com.amadeus.Response;
@@ -64,19 +65,19 @@ private boolean needsRefresh() {
   private Response fetchAccessToken() throws ResponseException {
     Configuration config = client.getConfiguration();
     return client.unauthenticatedRequest(
-           "POST",
-           "/v1/security/oauth2/token",
-            Params.with("grant_type", "client_credentials")
-                  .and("client_id", config.getClientId())
-                  .and("client_secret", config.getClientSecret()),
+           Constants.POST,
+           Constants.AUTH_URL,
+            Params.with(Constants.GRANT_TYPE, Constants.CLIENT_CREDENTIALS)
+                  .and(Constants.CLIENT_ID, config.getClientId())
+                  .and(Constants.CLIENT_SECRET, config.getClientSecret()),
            null
     );
   }
 
   // Store the fetched access token and expiry date
   private void storeAccessToken(JsonObject result) {
-    this.accessToken = result.get("access_token").getAsString();
-    int expiresIn = result.get("expires_in").getAsInt();
+    this.accessToken = result.get(Constants.ACCESS_TOKEN).getAsString();
+    int expiresIn = result.get(Constants.EXPIRES_IN).getAsInt();
     this.expiresAt = System.currentTimeMillis() + expiresIn * 1000L;
   }
 }