add FriendlyHttpResponseHandler, which dispatches text/json responses to

appropriate handlers, and provides noisy (Toasts to user) error handlers
by default

Author: jamur2

src/com/loopj/android/http/FriendlyHttpResponseHandler.java

@@ -0,0 +1,163 @@
+/*
+ Android Asynchronous Http Client
+ "Friendly" HTTP Response handler detects response content type and
+ dispatches to appropriate success and failure handlers.
+
+ Also, default error handlers provide noisy error messages to users by default,
+ rather than doing nothing.  eg., if the server goes down, pop up a Toast saying
+ as much rather than calling an empty error handler.
+
+ */
+
+package com.loopj.android.http;
+
+
+import org.apache.http.Header;
+import org.json.JSONArray;
+import org.json.JSONException;
+import org.json.JSONObject;
+import org.json.JSONTokener;
+
+import android.content.Context;
+
+import android.widget.Toast;
+
+public class FriendlyHttpResponseHandler extends
+        com.loopj.android.http.AsyncHttpResponseHandler {
+
+    Context context;
+
+    public FriendlyHttpResponseHandler(Context startContext) {
+        super();
+        context = startContext;
+    }
+
+    @Override
+    public void onFailure(Throwable e) {
+        String errorDescription = "An unknown error occurred.";
+        Toast toast = Toast.makeText(context, errorDescription,
+                Toast.LENGTH_SHORT);
+        toast.show();
+    }
+
+    public void onFailure(Throwable e, JSONObject errorResponse) {
+        String errorDescription = "An unknown error occurred.";
+        try {
+            if (errorResponse.has("error")) {
+                errorDescription = errorResponse.getString("error");
+            }
+        } catch (JSONException e1) {
+            e1.printStackTrace();
+        }
+        Toast toast = Toast.makeText(context, errorDescription,
+                Toast.LENGTH_SHORT);
+        toast.show();
+    }
+
+    @Override
+    public void onFailure(Throwable e, String errorResponse) {
+        Toast toast = Toast
+                .makeText(context, errorResponse, Toast.LENGTH_SHORT);
+        toast.show();
+    }
+
+    public void onFailure(Throwable e, JSONArray errorResponse) {
+        String errorDescription = "An unknown error occurred.";
+        Toast toast = Toast.makeText(context, errorDescription,
+                Toast.LENGTH_SHORT);
+        toast.show();
+    }
+
+    public void onSuccess(JSONObject response) {
+    }
+
+    public void onSuccess(JSONArray response) {
+    }
+
+    public void onSuccess(int statusCode, Header[] headers, JSONObject response) {
+        onSuccess(response);
+    }
+
+    public void onSuccess(int statusCode, Header[] headers, JSONArray response) {
+        onSuccess(response);
+    }
+
+    protected void handleFailureMessage(Throwable e, Header[] headers,
+            String responseBody) {
+        if (headers != null) {
+            for (Header header : headers) {
+                // XXX Find a header parsing library
+                if (header.getName().startsWith("Content-Type")
+                        && header.getValue().contains("application/json")) {
+                    try {
+                        Object jsonResponse = parseResponse(responseBody);
+                        handleFailureJsonMessage(headers, jsonResponse);
+                        return;
+                    } catch (JSONException e1) {
+                        onFailure(e1, responseBody);
+                    }
+                }
+            }
+        }
+        onFailure(e, responseBody);
+    }
+
+    protected void handleFailureJsonMessage(Header[] headers,
+            Object jsonResponse) {
+        if (jsonResponse instanceof JSONObject) {
+            JSONObject obj = (JSONObject) jsonResponse;
+            try {
+                if (obj.has("error") && (obj.getString("error").length() > 0)) {
+                    onFailure(
+                            new JSONException("Error: ".concat(obj
+                                    .getString("error"))), obj);
+                }
+            } catch (JSONException e) {
+                // No error found
+            }
+        }
+    }
+
+    protected void handleSuccessMessage(int statusCode, Header[] headers,
+            String responseBody) {
+        for (Header header : headers) {
+            if (header.getName().startsWith("Content-Type")
+                    && header.getValue().contains("application/json")) {
+                try {
+                    Object jsonResponse = parseResponse(responseBody);
+                    handleSuccessJsonMessage(statusCode, headers, jsonResponse);
+                } catch (JSONException e) {
+                    handleFailureMessage(e, headers, responseBody);
+                }
+            }
+        }
+        onSuccess(statusCode, headers, responseBody);
+    }
+
+    protected void handleSuccessJsonMessage(int statusCode, Header[] headers,
+            Object jsonResponse) {
+        if (jsonResponse instanceof JSONObject) {
+            onSuccess(statusCode, headers, (JSONObject) jsonResponse);
+        } else if (jsonResponse instanceof JSONArray) {
+            onSuccess(statusCode, headers, (JSONArray) jsonResponse);
+        } else {
+            onFailure(new JSONException("Unexpected type "
+                    + jsonResponse.getClass().getName()), (JSONObject) null);
+        }
+    }
+
+    protected Object parseResponse(String responseBody) throws JSONException {
+        Object result = null;
+        // trim the string to prevent start with blank, and test if the string
+        // is valid JSON, because the parser don't do this :(. If Json is not
+        // valid this will return null
+        responseBody = responseBody.trim();
+        if (responseBody.startsWith("{") || responseBody.startsWith("[")) {
+            result = new JSONTokener(responseBody).nextValue();
+        }
+        if (result == null) {
+            result = responseBody;
+        }
+        return result;
+    }
+}