Android Open Source - android-http Caching Example Activity

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License

The source code is released under:

Apache License

Java Source Code

/*
 * Copyright (C) 2012, 2013 the diamond:dogs|group
 *//from w w  w.j a  va2 s  .c o m
 * 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 at.diamonddogs.example.http.activity;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import android.app.ListActivity;
import android.net.Uri;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.ArrayAdapter;
import android.widget.Toast;
import at.diamonddogs.data.dataobjects.WebRequest;
import at.diamonddogs.example.http.R;
import at.diamonddogs.example.http.processor.RssProcessor;
import at.diamonddogs.service.net.HttpServiceAssister;
import at.diamonddogs.service.processor.ServiceProcessor;

/**
 * A simple caching example
 */
public class CachingExampleActivity extends ListActivity {

  private static final Logger LOGGER = LoggerFactory.getLogger(CachingExampleActivity.class.getSimpleName());

  private static final Uri RSS = Uri.parse("http://rss.golem.de/rss.php?tp=inet&feed=RSS2.0");

  private HttpServiceAssister assister;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.cachingexampleactivity);
    assister = new HttpServiceAssister(this);
    assister.runWebRequest(new RssHandler(), createGetRssRequest(), new RssProcessor());
  }

  /**
   * {@inheritDoc}
   */
  @Override
  protected void onResume() {
    super.onResume();
    assister.bindService();
  }

  /**
   * {@inheritDoc}
   */
  @Override
  protected void onPause() {
    super.onPause();
    assister.unbindService();
  }

  private WebRequest createGetRssRequest() {
    WebRequest wr = new WebRequest();
    wr.setUrl(RSS);
    wr.setProcessorId(RssProcessor.ID);

    // This is the important part, telling HttpService how long a WebRequest
    // will be saved. Since RssProcessor extends XMLProcessor, which extends
    // DataProcessor, the WebRequest's data will be cached automatically,
    // provided that cacheTime is not CACHE_NO.
    wr.setCacheTime(5000);

    // Enables offline caching. usually, cache data is deleted on retrieval
    // if it has expired even if the device is not online. If this flag is
    // set to true, cache data will not be removed if it has expired as long
    // as the device was offline during the request
    wr.setUseOfflineCache(true);
    return wr;
  }

  private final class RssHandler extends Handler {
    /**
     * {@inheritDoc}
     */
    @Override
    public void handleMessage(Message msg) {
      super.handleMessage(msg);
      if (msg.what == RssProcessor.ID) {
        if (msg.arg1 == ServiceProcessor.RETURN_MESSAGE_OK) {
          String[] items = (String[]) msg.obj;
          setListAdapter(new ArrayAdapter<String>(CachingExampleActivity.this, android.R.layout.simple_list_item_1,
              android.R.id.text1, items));
          Toast.makeText(CachingExampleActivity.this,
              "From cache -> " + msg.getData().getSerializable(ServiceProcessor.BUNDLE_EXTRA_MESSAGE_FROMCACHE),
              Toast.LENGTH_SHORT).show();
        } else {
          LOGGER.error("An error has occured.", msg.getData().getSerializable(ServiceProcessor.BUNDLE_EXTRA_MESSAGE_THROWABLE));
        }
      }
    }
  }
}

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