Add pre-processing for requests and responses.

Author: Noor Dawod

library/src/main/java/com/loopj/android/http/AsyncHttpClient.java

@@ -122,6 +122,9 @@ public class AsyncHttpClient {
     public static final String HEADER_CONTENT_DISPOSITION = "Content-Disposition";
     public static final String HEADER_ACCEPT_ENCODING = "Accept-Encoding";
     public static final String ENCODING_GZIP = "gzip";
+    public static final String ATTR_PRE_PROCESSED = "ahc.pre-processed";
+    public static final String TRUE = "true";
+    public static final String FALSE = "false";
 
     public static final int DEFAULT_MAX_CONNECTIONS = 10;
     public static final int DEFAULT_SOCKET_TIMEOUT = 10 * 1000;
@@ -138,6 +141,7 @@ public class AsyncHttpClient {
     private ExecutorService threadPool;
     private final Map<Context, List<RequestHandle>> requestMap;
     private final Map<String, String> clientHeaderMap;
+    private PreProcessingInterface preProcessor;
     private boolean isUrlEncodingEnabled = true;
 
     /**
@@ -272,6 +276,7 @@ public void process(HttpResponse response, HttpContext context) {
                 if (entity == null) {
                     return;
                 }
+
                 final Header encoding = entity.getContentEncoding();
                 if (encoding != null) {
                     for (HeaderElement element : encoding.getElements()) {
@@ -281,6 +286,18 @@ public void process(HttpResponse response, HttpContext context) {
                         }
                     }
                 }
+
+                if (preProcessor != null) {
+                    // Handle pre-processing only once.
+                    Object isPreProcessed = context.getAttribute(ATTR_PRE_PROCESSED);
+                    if (isPreProcessed != null && isPreProcessed.equals(TRUE)) {
+                        // Pre-process this request.
+                        preProcessor.onPreProcessResponse(response);
+
+                        // Indicate that this request has passed pre-processing.
+                        context.removeAttribute(ATTR_PRE_PROCESSED);
+                    }
+                }
             }
         });
 
@@ -300,6 +317,18 @@ public void process(final HttpRequest request, final HttpContext context) throws
                         authState.setCredentials(creds);
                     }
                 }
+
+                if (preProcessor != null) {
+                    // Handle pre-processing only once.
+                    Object isPreProcessed = context.getAttribute(ATTR_PRE_PROCESSED);
+                    if (isPreProcessed == null || !isPreProcessed.equals(TRUE)) {
+                        // Pre-process this request.
+                        preProcessor.onPreProcessRequest(request);
+
+                        // Indicate that this request has passed pre-processing.
+                        context.setAttribute(ATTR_PRE_PROCESSED, TRUE);
+                    }
+                }
             }
         }, 0);
 
@@ -370,6 +399,25 @@ public ExecutorService getThreadPool() {
         return threadPool;
     }
 
+    /**
+     * Sets a handler to be used for pre-processing requests and responses.
+     *
+     * @param handler an instance of {@link PreProcessingInterface} to use for
+     *        pre-processing requests and responses
+     */
+    public void setPreProcessor(PreProcessingInterface handler) {
+        this.preProcessor = handler;
+    }
+
+    /**
+     * Returns the current handler for pre-processing requests and responses.
+     *
+     * @return current handler used, or null if none is defined
+     */
+    public PreProcessingInterface getPreProcessor() {
+        return preProcessor;
+    }
+
     /**
      * Get the default threading pool to be used for this HTTP client.
      *
@@ -519,7 +567,7 @@ public int getResponseTimeout() {
      * Set response timeout limit (milliseconds). By default, this is set to
      * 10 seconds.
      *
-     * @param value Response  timeout in milliseconds, minimal value is 1000 (1 second).
+     * @param value Response timeout in milliseconds, minimal value is 1000 (1 second).
      */
     public void setResponseTimeout(int value) {
         responseTimeout = value < 1000 ? DEFAULT_SOCKET_TIMEOUT : value;

library/src/main/java/com/loopj/android/http/JsonStreamerEntity.java

@@ -56,8 +56,8 @@ public class JsonStreamerEntity implements HttpEntity {
     // automatically enlarge the buffer.
     private static final StringBuilder BUILDER = new StringBuilder(128);
 
-    private static final byte[] JSON_TRUE = "true".getBytes();
-    private static final byte[] JSON_FALSE = "false".getBytes();
+    private static final byte[] JSON_TRUE = AsyncHttpClient.TRUE.getBytes();
+    private static final byte[] JSON_FALSE = AsyncHttpClient.FALSE.getBytes();
     private static final byte[] JSON_NULL = "null".getBytes();
     private static final byte[] STREAM_NAME = escape("name");
     private static final byte[] STREAM_TYPE = escape("type");