Android Open Source - interdroid-swan Abstract Vdb Sensor

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License

The source code is released under:
Copyright (c) 2008-2011 Vrije Universiteit, The Netherlands All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the follo...
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Java Source Code

package interdroid.swan.sensors;
//from   w w w .j a v a  2s.c  o  m
import interdroid.swan.swansong.TimestampedValue;
import interdroid.vdb.content.EntityUriBuilder;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map.Entry;

import org.apache.avro.Schema;
import org.apache.avro.Schema.Type;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.net.Uri;

/**
 * Base class for sensors which store their data into a VDB database.
 * 
 * @author nick &lt;palmer@cs.vu.nl&gt;
 * 
 */
public abstract class AbstractVdbSensor extends AbstractSensorBase {

  /**
   * Access to logger.
   */
  private static final Logger LOG = LoggerFactory
      .getLogger(AbstractVdbSensor.class);

  private long mReadings = 0;
  private long mLastReadingTimestamp = 0;

  /**
   * Field which represents the timestamp for the reading.
   */
  private static final String TIMESTAMP_FIELD = "_timestamp";

  /**
   * The schema for the timestamp fields required on all rows.
   */
  protected static final String SCHEMA_TIMESTAMP_FIELDS;

  /**
   * The schema for the timestamp fields required on all rows.
   */
  protected static final String SCHEMA_ID_FIELDS;

  private static final String EXPRESSION_ID = "_expression_id";

  // Initialize the timestamp fields.
  static {
    // Bug in compiler. Set is called before .replace() !?!?
    String temp = "\n{'name':'" + TIMESTAMP_FIELD + "', "
        + "'ui.label':'timestamp', " + "'ui.list':'true', "
        + "'ui.widget':'timestamp', " + "'type':'long'},";

    SCHEMA_TIMESTAMP_FIELDS = temp.replace('\'', '"');

    // Bug in compiler. Set is called before .replace() !?!?
    temp = "\n{'name':'" + EXPRESSION_ID + "', "
        + "'ui.label':'expression id', " + "'ui.list':'false', "
        + "'type':'string'},";

    SCHEMA_ID_FIELDS = temp.replace('\'', '"');
  }

  /**
   * The uri for the database.
   */
  private Uri uri;

  /**
   * The schema for the sensor.
   */
  private Schema schema;

  public abstract String getScheme();

  /**
   * Initialize this sensor.
   */
  @Override
  public final void init() {
    schema = Schema.parse(getScheme());
    uri = EntityUriBuilder.nativeUri(schema.getNamespace(),
        schema.getName());
    LOG.debug("Sensor storing to URI: {}", uri);
  }

  // / =-=-=-=- VDB Specific helper methods -=-=-=-=

  /**
   * Stores the values to the content provider using this service as the
   * context. Fills in the timestamp and expiration before storing.
   * 
   * @param id
   *            the id
   * @param values
   *            the values to store
   * @param now
   *            the timestamp
   */
  public final void putValues(final String id, final ContentValues values,
      final long now) {
    updateReadings(now);
    notifyDataChangedForId(id);
    values.put(EXPRESSION_ID, id);
    putValues(getContentResolver(), uri, values, now);
  }

  /**
   * Stores the values to the content provider using this service as the
   * context. Fills in the timestamp and expiration before storing.
   * 
   * @param values
   *            the values to store
   * @param now
   *            the timestamp
   */
  public final void putValues(final ContentValues values, final long now) {
    updateReadings(now);
    putValues(getContentResolver(), uri, values, now);
    for (Entry<String, Object> key : values.valueSet()) {
      notifyDataChanged(key.getKey());
    }
  }

  private void updateReadings(long now) {
    if (now != mLastReadingTimestamp) {
      mReadings++;
      mLastReadingTimestamp = now;
    }
  }

  /**
   * Stores the values to the content provider using this given content
   * resolver. Fills in the timestamp and expiration before storing.
   * 
   * @param resolver
   *            the resolver to store with
   * @param values
   *            the values to store
   * @param now
   *            the timestamp
   * @param uri
   *            the uri to store into
   */
  public static final void putValues(final ContentResolver resolver,
      final Uri uri, final ContentValues values, final long now) {
    values.put(TIMESTAMP_FIELD, now);
    resolver.insert(uri, values);
  }

  /**
   * @param fieldName
   *            the name of the field
   * @return the type of the field
   */
  private Type getType(final String fieldName) {
    return schema.getField(fieldName).schema().getType();
  }

  @Override
  public List<TimestampedValue> getValues(final String id, final long now,
      final long timespan) {
    String fieldName = registeredValuePaths.get(id);
    return getValuesForValuePath(fieldName, id, now, timespan);
  }

  public List<TimestampedValue> getValuesForValuePath(final String fieldName,
      String id, final long now, final long timespan) {
    Type fieldType = getType(fieldName);
    Cursor values;
    if (schema.getField(EXPRESSION_ID) != null) {
      values = getValuesCursor(this, uri, new String[] { fieldName },
          now, timespan, id);
    } else {
      values = getValuesCursor(this, uri, new String[] { fieldName },
          now, timespan, null);
    }
    List<TimestampedValue> ret = null;
    if (values != null && values.moveToFirst()) {
      int column = values.getColumnIndex(fieldName);
      ret = new ArrayList<TimestampedValue>(values.getCount());
      do {
        switch (fieldType) {
        case INT:
          ret.add(new TimestampedValue(values.getInt(column), values
              .getLong(0)));
          break;
        case LONG:
          ret.add(new TimestampedValue(values.getLong(column), values
              .getLong(0)));
          break;
        case ENUM:
        case STRING:
          ret.add(new TimestampedValue(values.getString(column),
              values.getLong(0)));
          break;
        case FLOAT:
          ret.add(new TimestampedValue(values.getFloat(column),
              values.getLong(0)));
          break;
        case DOUBLE:
          ret.add(new TimestampedValue(values.getDouble(column),
              values.getLong(0)));
          break;
        case FIXED:
        case BYTES:
          ret.add(new TimestampedValue(values.getBlob(column), values
              .getLong(0)));
        default:
          throw new RuntimeException("Unsupported type.");
        }
        // Limit to one result if timespan is zero
        if (timespan == 0) {
          break;
        }
      } while (values.moveToNext());
    }
    try {
      if (values != null) {
        values.close();
      }
    } catch (Exception e) {
      LOG.warn("Error closing cursor ignored.", e);
    }
    if (ret == null) {
      ret = new ArrayList<TimestampedValue>(0);
    }
    return ret;
  }

  /**
   * @param context
   *            the context to use to resolve
   * @param uri
   *            the uri for the data
   * @param values
   *            the values to be pulled
   * @param now
   *            the time
   * @param timespan
   *            the timespan
   * @param id
   * @return a cursor with the value data
   */
  protected static Cursor getValuesCursor(final Context context,
      final Uri uri, final String[] values, final long now,
      final long timespan, String id) {
    LOG.debug("timespan: {} end: {}", timespan, now);

    String[] projection = new String[values.length + 1];
    System.arraycopy(values, 0, projection, 1, values.length);
    projection[0] = TIMESTAMP_FIELD;

    LOG.debug("Projection: {} {}", projection, projection.length);

    String where = null;
    String[] whereArgs = null;

    // Build where args
    if (id != null) {
      // we might have a non null id, but values stored without an
      // expression id (e.g. id independent values), therefore we also
      // accept expression ids that are null.
      where = "( " + EXPRESSION_ID + "=? OR " + EXPRESSION_ID
          + " is null ) ";

      if (timespan <= 0) {
        whereArgs = new String[] { id };
      } else {
        whereArgs = new String[] { id, String.valueOf(now - timespan) };
      }
    } else {
      if (timespan > 0) {
        whereArgs = new String[] { String.valueOf(now - timespan) };
      }
    }

    Cursor c = null;
    if (timespan <= 0) {

      c = context.getContentResolver().query(uri, projection, where,
          whereArgs,
          // If timespan is zero we just pull the last one in time
          TIMESTAMP_FIELD + " DESC LIMIT 1");

    } else {

      c = context.getContentResolver().query(
          uri,
          projection,
          (where == null ? "" : where + " AND ") + TIMESTAMP_FIELD
              + " >= ? ", whereArgs, TIMESTAMP_FIELD + " ASC");

    }

    return c;
  }

  @Override
  public long getReadings() {
    return mReadings;
  }
}
Java Source Code List
