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app/src/main/java/com/android/volley/toolbox/RequestFuture.java

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+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+import com.android.volley.Request;
+import com.android.volley.Response;
+import com.android.volley.VolleyError;
+
+/**
+ * A Future that represents a Volley request.
+ *
+ * Used by providing as your response and error listeners. For example:
+ * <pre>
+ * RequestFuture&lt;JSONObject&gt; future = RequestFuture.newFuture();
+ * MyRequest request = new MyRequest(URL, future, future);
+ *
+ * // If you want to be able to cancel the request:
+ * future.setRequest(requestQueue.add(request));
+ *
+ * // Otherwise:
+ * requestQueue.add(request);
+ *
+ * try {
+ *   JSONObject response = future.get();
+ *   // do something with response
+ * } catch (InterruptedException e) {
+ *   // handle the error
+ * } catch (ExecutionException e) {
+ *   // handle the error
+ * }
+ * </pre>
+ *
+ * @param <T> The type of parsed response this future expects.
+ */
+public class RequestFuture<T> implements Future<T>, Response.Listener<T>,
+       Response.ErrorListener {
+    private Request<?> mRequest;
+    private boolean mResultReceived = false;
+    private T mResult;
+    private VolleyError mException;
+
+    public static <E> RequestFuture<E> newFuture() {
+        return new RequestFuture<E>();
+    }
+
+    private RequestFuture() {}
+
+    public void setRequest(Request<?> request) {
+        mRequest = request;
+    }
+
+    @Override
+    public synchronized boolean cancel(boolean mayInterruptIfRunning) {
+        if (mRequest == null) {
+            return false;
+        }
+
+        if (!isDone()) {
+            mRequest.cancel();
+            return true;
+        } else {
+            return false;
+        }
+    }
+
+    @Override
+    public T get() throws InterruptedException, ExecutionException {
+        try {
+            return doGet(null);
+        } catch (TimeoutException e) {
+            throw new AssertionError(e);
+        }
+    }
+
+    @Override
+    public T get(long timeout, TimeUnit unit)
+            throws InterruptedException, ExecutionException, TimeoutException {
+        return doGet(TimeUnit.MILLISECONDS.convert(timeout, unit));
+    }
+
+    private synchronized T doGet(Long timeoutMs)
+            throws InterruptedException, ExecutionException, TimeoutException {
+        if (mException != null) {
+            throw new ExecutionException(mException);
+        }
+
+        if (mResultReceived) {
+            return mResult;
+        }
+
+        if (timeoutMs == null) {
+            wait(0);
+        } else if (timeoutMs > 0) {
+            wait(timeoutMs);
+        }
+
+        if (mException != null) {
+            throw new ExecutionException(mException);
+        }
+
+        if (!mResultReceived) {
+            throw new TimeoutException();
+        }
+
+        return mResult;
+    }
+
+    @Override
+    public boolean isCancelled() {
+        if (mRequest == null) {
+            return false;
+        }
+        return mRequest.isCanceled();
+    }
+
+    @Override
+    public synchronized boolean isDone() {
+        return mResultReceived || mException != null || isCancelled();
+    }
+
+    @Override
+    public synchronized void onResponse(T response) {
+        mResultReceived = true;
+        mResult = response;
+        notifyAll();
+    }
+
+    @Override
+    public synchronized void onErrorResponse(VolleyError error) {
+        mException = error;
+        notifyAll();
+    }
+}
+