fr.mixit.android.io.JSONHandler.java Source code

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Here is the source code for fr.mixit.android.io.JSONHandler.java

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/*
 * Copyright 2010 Peter Kuterna
 *
 * 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 fr.mixit.android.io;

import android.content.ContentProviderOperation;
import android.content.ContentResolver;
import android.content.OperationApplicationException;
import android.database.Cursor;
import android.net.Uri;
import android.os.RemoteException;
import android.util.Log;
import fr.mixit.android.utils.Sets;
import org.json.JSONArray;
import org.json.JSONException;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Set;

/**
 * Abstract class that handles reading and parsing an {@link org.json.JSONArray} into
 * a set of {@link android.content.ContentProviderOperation}. It catches exceptions and
 * rethrows them as {@link JSONHandlerException}. Any local
 * {@link android.content.ContentProvider} exceptions are considered unrecoverable.
 * <p>
 * This class is only designed to handle simple one-way synchronization.
 */
public abstract class JSONHandler extends BaseHandler {

    private static final String TAG = "JSONHandler";

    public JSONHandler(String mAuthority) {
        super(mAuthority);
    }

    /**
      * Parse the given {@link org.json.JSONArray}, turning into a series of
      * {@link android.content.ContentProviderOperation} that are immediately applied using the
      * given {@link android.content.ContentResolver}.
      */
    public void parseAndApply(ArrayList<JSONArray> entries, ContentResolver resolver) throws JSONHandlerException {
        try {
            final ArrayList<ContentProviderOperation> batch = parse(entries, resolver);
            resolver.applyBatch(getAuthority(), batch);
        } catch (JSONException e) {
            throw new JSONHandlerException("Problem parsing JSON response", e);
        } catch (RemoteException e) {
            throw new RuntimeException("Problem applying batch operation", e);
        } catch (OperationApplicationException e) {
            throw new RuntimeException("Problem applying batch operation", e);
        }
    }

    //application/json
    /**
     * Parse the given {@link JSONHandler}, returning a set of
     * {@link android.content.ContentProviderOperation} that will bring the
     * {@link android.content.ContentProvider} into sync with the parsed data.
     */
    public abstract ArrayList<ContentProviderOperation> parse(ArrayList<JSONArray> entries,
            ContentResolver resolver) throws JSONException;

    protected static boolean isRowExisting(Uri uri, String[] projection, ContentResolver resolver) {
        final Cursor cursor = resolver.query(uri, projection, null, null, null);
        try {
            if (!cursor.moveToFirst())
                return false;
        } finally {
            cursor.close();
        }
        return true;
    }

    /**
     * Returns those id's from a {@link android.net.Uri} that were not found in a given set.
     */
    protected static HashSet<String> getLostIds(Set<String> ids, Uri uri, String[] projection, int idColumnIndex,
            ContentResolver resolver) {
        final HashSet<String> lostIds = Sets.newHashSet();

        final Cursor cursor = resolver.query(uri, projection, null, null, null);
        try {
            while (cursor.moveToNext()) {
                final String id = cursor.getString(idColumnIndex);
                if (!ids.contains(id)) {
                    lostIds.add(id);
                }
            }
        } finally {
            cursor.close();
        }

        if (!lostIds.isEmpty()) {
            Log.d(TAG, "Found " + lostIds.size() + " for " + uri.toString() + " that need to be removed.");
        }

        return lostIds;
    }

    /**
      * General {@link java.io.IOException} that indicates a problem occured while
      * parsing or applying an {@link org.json.JSONArray}.
      */
    public static class JSONHandlerException extends IOException {
        public JSONHandlerException(String message) {
            super(message);
        }

        public JSONHandlerException(String message, Throwable cause) {
            super(message);
            initCause(cause);
        }

        @Override
        public String toString() {
            if (getCause() != null) {
                return getLocalizedMessage() + ": " + getCause();
            } else {
                return getLocalizedMessage();
            }
        }
    }

}