Added global response handlers.

Stephen Cobbe · Stephen Cobbe · commit 6d670577e8cc · 2017-05-11T13:54:34.000-07:00
diff --git a/examples/global-callbacks/.gitignore b/examples/global-callbacks/.gitignore
@@ -0,0 +1,2 @@
+/build/
+/target/
diff --git a/examples/global-callbacks/ReadMe.md b/examples/global-callbacks/ReadMe.md
@@ -0,0 +1,11 @@
+# Global Handlers Example
+
+This repo contains an advanced use-case example (global route error and network error response callbacks).
+
+Client can supply a callback factory, which allows for consistent, global handling of route-specific error types, as well as general network errors.
+
+Normally, error handling is done on a request-by-request basis. However, it is convenient to handle some error behavior consistently, regardless of the request or the endpoint.
+
+For implementing global error handling for general networking errors like an auth error, `getNetworkErrorCallback` should be implemented. For implementing global error handling for route-specific errors, one of the `getRouteErrorCallback` should be implemented.
+
+To run this example, please replace `"<ACCESS TOKEN>"` in `Main.java` with your access token. See the online tutorial for more details on how to generate an access token.
diff --git a/examples/global-callbacks/build.gradle b/examples/global-callbacks/build.gradle
@@ -0,0 +1,2 @@
+
+description = 'Global Callbacks Example (Dropbox Core API SDK)'
diff --git a/examples/global-callbacks/src/main/java/com/dropbox/core/examples/global-callbacks/DbxExampleGlobalCallbackFactory.java b/examples/global-callbacks/src/main/java/com/dropbox/core/examples/global-callbacks/DbxExampleGlobalCallbackFactory.java
@@ -0,0 +1,25 @@
+package com.dropbox.core.examples.global_callbacks;
+
+import com.dropbox.core.v2.callbacks.DbxGlobalCallbackFactory;
+import com.dropbox.core.v2.callbacks.DbxRouteErrorCallback;
+import com.dropbox.core.v2.callbacks.DbxNetworkErrorCallback;
+import com.dropbox.core.v2.files.ListFolderError;
+import com.dropbox.core.v2.files.LookupError;
+
+public class DbxExampleGlobalCallbackFactory implements DbxGlobalCallbackFactory {
+    @Override
+    public <T> DbxRouteErrorCallback<T> createRouteErrorCallback(T routeError) {
+        if (routeError instanceof ListFolderError) {
+            return new DbxExampleListFolderErrorCallback<T>();
+        } else if (routeError instanceof LookupError) {
+            return new DbxExampleLookupErrorCallback<T>();
+        }
+
+        return null;
+    }
+
+    @Override
+    public DbxExampleNetworkErrorCallback createNetworkErrorCallback() {
+        return new DbxExampleNetworkErrorCallback();
+    }
+}
diff --git a/examples/global-callbacks/src/main/java/com/dropbox/core/examples/global-callbacks/DbxExampleListFolderErrorCallback.java b/examples/global-callbacks/src/main/java/com/dropbox/core/examples/global-callbacks/DbxExampleListFolderErrorCallback.java
@@ -0,0 +1,13 @@
+package com.dropbox.core.examples.global_callbacks;
+
+import com.dropbox.core.v2.callbacks.DbxRouteErrorCallback;
+import com.dropbox.core.v2.files.ListFolderError;
+
+public class DbxExampleListFolderErrorCallback<T> extends DbxRouteErrorCallback<T> {
+    @Override
+    public void run() {
+        System.out.println("GLOBAL ROUTE ERROR HANDLER (ListFolderError): " + this.getRouteError() + "\n");
+        // do some work
+    }
+}
+
diff --git a/examples/global-callbacks/src/main/java/com/dropbox/core/examples/global-callbacks/DbxExampleLookupErrorCallback.java b/examples/global-callbacks/src/main/java/com/dropbox/core/examples/global-callbacks/DbxExampleLookupErrorCallback.java
@@ -0,0 +1,12 @@
+package com.dropbox.core.examples.global_callbacks;
+
+import com.dropbox.core.v2.callbacks.DbxRouteErrorCallback;
+import com.dropbox.core.v2.files.LookupError;
+
+public class DbxExampleLookupErrorCallback<T> extends DbxRouteErrorCallback<T> {
+    @Override
+    public void run() {
+        System.out.println("GLOBAL ROUTE ERROR HANDLER (LookupError): " + this.getRouteError() + "\n");
+        // do some work
+    }
+}
diff --git a/examples/global-callbacks/src/main/java/com/dropbox/core/examples/global-callbacks/DbxExampleNetworkErrorCallback.java b/examples/global-callbacks/src/main/java/com/dropbox/core/examples/global-callbacks/DbxExampleNetworkErrorCallback.java
@@ -0,0 +1,14 @@
+package com.dropbox.core.examples.global_callbacks;
+
+import com.dropbox.core.v2.callbacks.DbxNetworkErrorCallback;
+import com.dropbox.core.InvalidAccessTokenException;
+
+public class DbxExampleNetworkErrorCallback extends DbxNetworkErrorCallback {
+    @Override
+    public void run() {
+        if (this.getNetworkError() instanceof InvalidAccessTokenException) {
+            System.out.println("GLOBAL NETWORK ERROR HANDLER: " + this.getNetworkError() + "\n");
+            // do some work
+        }
+    }
+}
diff --git a/examples/global-callbacks/src/main/java/com/dropbox/core/examples/global-callbacks/Main.java b/examples/global-callbacks/src/main/java/com/dropbox/core/examples/global-callbacks/Main.java
@@ -0,0 +1,57 @@
+package com.dropbox.core.examples.global_callbacks;
+
+import com.dropbox.core.DbxException;
+import com.dropbox.core.DbxRequestConfig;
+import com.dropbox.core.DbxRequestUtil;
+import com.dropbox.core.v2.callbacks.DbxGlobalCallbackFactory;
+import com.dropbox.core.v2.callbacks.DbxRouteErrorCallback;
+import com.dropbox.core.v2.callbacks.DbxNetworkErrorCallback;
+import com.dropbox.core.v2.DbxClientV2;
+import com.dropbox.core.v2.files.FileMetadata;
+import com.dropbox.core.v2.files.ListFolderError;
+import com.dropbox.core.v2.files.ListFolderErrorException;
+import com.dropbox.core.v2.files.ListFolderResult;
+import com.dropbox.core.v2.files.Metadata;
+import com.dropbox.core.v2.users.FullAccount;
+
+import java.util.List;
+
+import java.io.FileInputStream;
+import java.io.InputStream;
+import java.io.IOException;
+
+public class Main {
+    private static final String ACCESS_TOKEN = "<ACCESS TOKEN>";
+
+    public static void main(String args[]) throws DbxException, IOException {
+        // Create Dropbox client
+        DbxRequestConfig config = new DbxRequestConfig("dropbox/java-tutorial");
+        DbxClientV2 client = new DbxClientV2(config, ACCESS_TOKEN);
+
+        // Instantiate factory and set shared factory
+        DbxRequestUtil.sharedCallbackFactory = new DbxExampleGlobalCallbackFactory();
+
+        try {
+            // Get files and folder metadata from Dropbox root directory
+            client.files().listFolder("/does/not/exist");
+        }
+        catch (ListFolderErrorException ex) {
+            System.err.println("STANDARD ROUTE ERROR HANDLER: " + ex.errorValue + "\n");
+        }
+        catch (DbxException ex) {
+            System.err.println("STANDARD NETWORK ERROR HANDLER: " + ex + "\n");
+        }
+
+//        try {
+//            // Get files and folder metadata from Dropbox root directory
+//            client.auth().tokenRevoke();
+//            client.files().listFolder("/does/not/exist");
+//        }
+//        catch (ListFolderErrorException ex) {
+//            System.err.println("STANDARD ROUTE ERROR HANDLER2: " + ex.errorValue + "\n");
+//        }
+//        catch (DbxException ex) {
+//            System.err.println("STANDARD NETWORK ERROR HANDLER2: " + ex + "\n");
+//        }
+    }
+}
diff --git a/examples/settings.gradle b/examples/settings.gradle
@@ -1,6 +1,7 @@
 rootProject.name = 'examples'
 include ':account-info'
 include ':authorize'
+include ':global-callbacks'
 include ':longpoll'
 include ':tutorial'
 include ':upgrade-oauth1-token'
diff --git a/examples/tutorial/src/main/java/com/dropbox/core/examples/tutorial/Main.java b/examples/tutorial/src/main/java/com/dropbox/core/examples/tutorial/Main.java
@@ -2,6 +2,9 @@
 
 import com.dropbox.core.DbxException;
 import com.dropbox.core.DbxRequestConfig;
+import com.dropbox.core.v2.callbacks.DbxGlobalCallbackFactory;
+import com.dropbox.core.v2.callbacks.DbxRouteErrorCallback;
+import com.dropbox.core.v2.callbacks.DbxNetworkErrorCallback;
 import com.dropbox.core.v2.DbxClientV2;
 import com.dropbox.core.v2.files.FileMetadata;
 import com.dropbox.core.v2.files.ListFolderResult;
diff --git a/src/main/java/com/dropbox/core/DbxRequestUtil.java b/src/main/java/com/dropbox/core/DbxRequestUtil.java
@@ -1,10 +1,7 @@
 package com.dropbox.core;
 
-import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.io.InputStream;
 import java.io.UnsupportedEncodingException;
-import java.lang.reflect.Type;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.net.URLEncoder;
@@ -15,12 +12,13 @@
 import java.util.Map;
 import java.util.Random;
 
-import com.dropbox.core.stone.StoneSerializer;
 import com.dropbox.core.http.HttpRequestor;
 import com.dropbox.core.json.JsonReadException;
 import com.dropbox.core.json.JsonReader;
 import com.dropbox.core.util.IOUtil;
 import com.dropbox.core.util.StringUtil;
+import com.dropbox.core.v2.callbacks.DbxGlobalCallbackFactory;
+import com.dropbox.core.v2.callbacks.DbxNetworkErrorCallback;
 
 import static com.dropbox.core.util.StringUtil.jq;
 import static com.dropbox.core.util.LangUtil.mkAssert;
@@ -30,6 +28,8 @@
 public final class DbxRequestUtil {
     private static final Random RAND = new Random();
 
+    public static DbxGlobalCallbackFactory sharedCallbackFactory;
+
     public static String encodeUrlParam(String s) {
         try {
             return URLEncoder.encode(s, "UTF-8");
@@ -278,44 +278,63 @@ public static String parseErrorBody(String requestId, int statusCode, byte[] bod
 
     public static DbxException unexpectedStatus(HttpRequestor.Response response)
         throws NetworkIOException, BadResponseException {
+        DbxException networkError;
+
         String requestId = getRequestId(response);
         byte[] body = loadErrorBody(response);
         String message = parseErrorBody(requestId, response.getStatusCode(), body);
 
         switch (response.getStatusCode()) {
             case 400:
-                return new BadRequestException(requestId, message);
+                networkError = new BadRequestException(requestId, message);
+                break;
             case 401:
-                return new InvalidAccessTokenException(requestId, message);
+                networkError = new InvalidAccessTokenException(requestId, message);
+                break;
             case 429:
                 try {
                     int backoffSecs = Integer.parseInt(getFirstHeader(response, "Retry-After"));
-                    return new RateLimitException(requestId, message, backoffSecs, TimeUnit.SECONDS);
+                    networkError = new RateLimitException(requestId, message, backoffSecs, TimeUnit.SECONDS);
+                    break;
                 } catch (NumberFormatException ex) {
-                    return new BadResponseException(requestId, "Invalid value for HTTP header: \"Retry-After\"");
+                    networkError = new BadResponseException(requestId, "Invalid value for HTTP header: \"Retry-After\"");
+                    break;
                 }
             case 500:
-                return new ServerException(requestId, message);
+                networkError = new ServerException(requestId, message);
+                break;
             case 503:
                 // API v1 may include Retry-After in 503 responses, v2 does not
                 String retryAfter = getFirstHeaderMaybe(response, "Retry-After");
                 try {
                     if (retryAfter != null && !retryAfter.trim().isEmpty()) {
                         int backoffSecs = Integer.parseInt(retryAfter);
-                        return new RetryException(requestId, message, backoffSecs, TimeUnit.SECONDS);
+                        networkError = new RetryException(requestId, message, backoffSecs, TimeUnit.SECONDS);
+                        break;
                     } else {
-                        return new RetryException(requestId, message);
+                        networkError = new RetryException(requestId, message);
+                        break;
                     }
                 } catch (NumberFormatException ex) {
-                    return new BadResponseException(requestId, "Invalid value for HTTP header: \"Retry-After\"");
+                    networkError = new BadResponseException(requestId, "Invalid value for HTTP header: \"Retry-After\"");
+                    break;
                 }
             default:
-                return new BadResponseCodeException(
+                networkError = new BadResponseCodeException(
                     requestId,
                     "unexpected HTTP status code: " + response.getStatusCode() + ": " + message,
                     response.getStatusCode()
                 );
         }
+
+        DbxGlobalCallbackFactory factory = DbxRequestUtil.sharedCallbackFactory;
+        if (factory != null) {
+            DbxNetworkErrorCallback callback = factory.createNetworkErrorCallback();
+            callback.setNetworkError(networkError);
+            callback.run();
+        }
+
+        return networkError;
     }
 
     public static <T> T readJsonFromResponse(JsonReader<T> reader, HttpRequestor.Response response)
diff --git a/src/main/java/com/dropbox/core/DbxWrappedException.java b/src/main/java/com/dropbox/core/DbxWrappedException.java
@@ -1,11 +1,15 @@
 package com.dropbox.core;
 
 import java.io.IOException;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
 
 import com.fasterxml.jackson.core.JsonParseException;
 
 import com.dropbox.core.stone.StoneSerializer;
 import com.dropbox.core.http.HttpRequestor;
+import com.dropbox.core.v2.callbacks.DbxGlobalCallbackFactory;
+import com.dropbox.core.v2.callbacks.DbxRouteErrorCallback;
 
 /**
  * For internal use only.
@@ -42,6 +46,42 @@ public static <T> DbxWrappedException fromResponse(StoneSerializer<T> errSeriali
         ApiErrorResponse<T> apiResponse = new ApiErrorResponse.Serializer<T>(errSerializer)
             .deserialize(response.getBody());
 
-        return new DbxWrappedException(apiResponse.getError(), requestId, apiResponse.getUserMessage());
+        T routeError = apiResponse.getError();
+
+        DbxGlobalCallbackFactory factory = DbxRequestUtil.sharedCallbackFactory;
+        DbxWrappedException.executeBlockForObject(factory, routeError);
+        DbxWrappedException.executeOtherBlocks(factory, routeError);
+
+        return new DbxWrappedException(routeError, requestId, apiResponse.getUserMessage());
+    }
+
+    public static void executeOtherBlocks(DbxGlobalCallbackFactory factory, Object routeError) {
+        try {
+            // Recursively looks at union errors and the union's current tag type. If there is a handler
+            // for the current tag type, it is executed.
+            Method m = routeError.getClass().getMethod("tag");
+            Object result = m.invoke(routeError);
+            String fName = result.toString().toLowerCase() + "value";
+            for(Field f : routeError.getClass().getDeclaredFields() ) {
+                if (f.getName().equalsIgnoreCase(fName) ) {
+                    f.setAccessible(true);
+                    Object fieldValue = f.get(routeError);
+                    DbxWrappedException.executeBlockForObject(factory, fieldValue);
+                    break;
+                }
+            }
+        } catch (Exception e) {
+            // No handling
+        }
+    }
+
+    public static <T> void executeBlockForObject(DbxGlobalCallbackFactory factory, T routeError) {
+        if (factory != null) {
+            DbxRouteErrorCallback<T> callback = factory.createRouteErrorCallback(routeError);
+            if (callback != null) {
+                callback.setRouteError(routeError);
+                callback.run();
+            }
+        }
     }
 }
diff --git a/src/main/java/com/dropbox/core/v2/callbacks/DbxGlobalCallbackFactory.java b/src/main/java/com/dropbox/core/v2/callbacks/DbxGlobalCallbackFactory.java
@@ -0,0 +1,17 @@
+package com.dropbox.core.v2.callbacks;
+
+/**
+ * Client should implement methods in this class to allow for consistent, global handling of route-specific error types,
+ * as well as general network errors. Normally, error handling is done on a request-by-request basis.
+ * However, it is convenient to handle some error behavior consistently, regardless of the request or the endpoint.
+ * For implementing global error handling for general networking errors like an auth error, `createNetworkErrorCallback`
+ * should be implemented. For implementing global error handling for route-specific errors, the
+ * `createRouteErrorCallback` should be implemented.
+ */
+public interface DbxGlobalCallbackFactory {
+    // Should instantiate separate callback object on each method invocation
+    <T> DbxRouteErrorCallback<T> createRouteErrorCallback(T routeError);
+
+    // Should instantiate separate callback object on each method invocation
+    DbxNetworkErrorCallback createNetworkErrorCallback();
+}
diff --git a/src/main/java/com/dropbox/core/v2/callbacks/DbxNetworkErrorCallback.java b/src/main/java/com/dropbox/core/v2/callbacks/DbxNetworkErrorCallback.java
@@ -0,0 +1,18 @@
+package com.dropbox.core.v2.callbacks;
+
+import com.dropbox.core.DbxException;
+
+/**
+ * Abstract class for network error callback.
+ */
+public abstract class DbxNetworkErrorCallback implements Runnable {
+    private DbxException networkError = null;
+
+    public DbxException getNetworkError() {
+        return networkError;
+    }
+
+    public void setNetworkError(DbxException networkError) {
+        this.networkError = networkError;
+    }
+}
diff --git a/src/main/java/com/dropbox/core/v2/callbacks/DbxRouteErrorCallback.java b/src/main/java/com/dropbox/core/v2/callbacks/DbxRouteErrorCallback.java
@@ -0,0 +1,16 @@
+package com.dropbox.core.v2.callbacks;
+
+/**
+ * Interface for route error callback.
+ */
+public abstract class DbxRouteErrorCallback<T> implements Runnable {
+    private T routeError = null;
+
+    public T getRouteError() {
+        return routeError;
+    }
+
+    public void setRouteError(T routeError) {
+        this.routeError = routeError;
+    }
+}

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+`
	`2`	`+description = 'Global Callbacks Example (Dropbox Core API SDK)'`