com.seguetech.zippy.data.orm.ORMLoader.java Source code

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Here is the source code for com.seguetech.zippy.data.orm.ORMLoader.java

Source

package com.seguetech.zippy.data.orm;

/*
 * Based on CursorLoader.java:
 * 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.
 */

import android.content.Context;
import android.database.ContentObserver;
import android.database.Cursor;
import android.support.v4.content.AsyncTaskLoader;

import com.j256.ormlite.android.AndroidCompiledStatement;
import com.j256.ormlite.android.apptools.OrmLiteSqliteOpenHelper;
import com.j256.ormlite.stmt.PreparedQuery;
import com.j256.ormlite.stmt.StatementBuilder.StatementType;

import java.io.FileDescriptor;
import java.io.PrintWriter;
import java.sql.SQLException;

@SuppressWarnings("unused")
public class ORMLoader<T> extends AsyncTaskLoader<Cursor> {
    final ForceLoadContentObserver mObserver;
    private OrmLiteSqliteOpenHelper mDatabaseHelper;

    private Cursor mCursor;
    private PreparedQuery<T> mQuery;

    public ORMLoader(Context context, OrmLiteSqliteOpenHelper databaseHelper, PreparedQuery<T> query)
            throws Exception {
        super(context);
        if (databaseHelper == null) {
            throw new Exception("Database Helper cannot be null");
        }
        if (query == null) {
            throw new Exception("Query cannot be null");
        }
        mDatabaseHelper = databaseHelper;
        mObserver = new ForceLoadContentObserver();
        mQuery = query;
    }

    /* Runs on a worker thread */
    @Override
    public Cursor loadInBackground() {
        Cursor cursor;
        try {
            cursor = ((AndroidCompiledStatement) mQuery
                    .compile(mDatabaseHelper.getConnectionSource().getReadOnlyConnection(), StatementType.SELECT))
                            .getCursor();
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }

        if (cursor != null) {
            cursor.getCount();
            registerContentObserver(cursor, mObserver);
        }
        return cursor;
    }

    /**
     * Registers an observer to get notifications from the content provider
     * when the cursor needs to be refreshed.
     */
    void registerContentObserver(Cursor cursor, ContentObserver observer) {
        cursor.registerContentObserver(observer);
    }

    /* Runs on the UI thread */
    @Override
    public void deliverResult(Cursor cursor) {
        if (isReset()) {
            // An async query came in while the loader is stopped
            if (cursor != null) {
                cursor.close();
            }
            return;
        }
        Cursor oldCursor = mCursor;
        mCursor = cursor;

        if (isStarted()) {
            super.deliverResult(cursor);
        }

        if (oldCursor != null && oldCursor != cursor && !oldCursor.isClosed()) {
            oldCursor.close();
        }
    }

    /**
     * Starts an asynchronous load of the contacts list data. When the result is ready the callbacks
     * will be called on the UI thread. If a previous load has been completed and is still valid
     * the result may be passed to the callbacks immediately.
     * <p/>
     * Must be called from the UI thread
     */
    @Override
    protected void onStartLoading() {
        if (mCursor != null) {
            deliverResult(mCursor);
        }
        if (takeContentChanged() || mCursor == null) {
            forceLoad();
        }
    }

    /**
     * Must be called from the UI thread
     */
    @Override
    protected void onStopLoading() {
        // Attempt to cancel the current load task if possible.
        cancelLoad();
    }

    @Override
    public void onCanceled(Cursor cursor) {
        if (cursor != null && !cursor.isClosed()) {
            cursor.close();
        }
    }

    @Override
    protected void onReset() {

        // Ensure the loader is stopped
        onStopLoading();

        if (mCursor != null && !mCursor.isClosed()) {
            mCursor.close();
        }

        mCursor = null;
        super.onReset();
    }

    public void setPreparedQuery(PreparedQuery<T> preparedQuery) {
        this.mQuery = preparedQuery;
    }

    @Override
    public void dump(String prefix, FileDescriptor fd, PrintWriter writer, String[] args) {
        super.dump(prefix, fd, writer, args);
        writer.print(prefix);
        writer.print("mCursor=");
        writer.println(mCursor);
    }
}