Java tutorial
/* * Copyright (C) 2013 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. */ package cn.edu.wyu.documentviewer; import static cn.edu.wyu.documentviewer.DocumentsActivity.TAG; import java.io.IOException; import java.util.ArrayList; import java.util.Collection; import java.util.List; import org.apache.commons.io.IOUtils; import android.app.Fragment; import android.app.FragmentManager; import android.app.FragmentTransaction; import android.app.LoaderManager.LoaderCallbacks; import android.content.ContentResolver; import android.content.Context; import android.content.Loader; import android.database.Cursor; import android.graphics.drawable.Drawable; import android.net.Uri; import android.os.Bundle; import android.os.CancellationSignal; import android.text.Spannable; import android.text.SpannableStringBuilder; import android.text.TextUtils.TruncateAt; import android.text.style.ImageSpan; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.AdapterView; import android.widget.AdapterView.OnItemClickListener; import android.widget.BaseAdapter; import android.widget.ImageView; import android.widget.ListView; import android.widget.TextView; import cn.edu.wyu.documentviewer.R; import cn.edu.wyu.documentviewer.DocumentsActivity.State; import cn.edu.wyu.documentviewer.RecentsProvider.RecentColumns; import cn.edu.wyu.documentviewer.model.DocumentStack; import cn.edu.wyu.documentviewer.model.DurableUtils; import cn.edu.wyu.documentviewer.model.RootInfo; import com.google.common.collect.Lists; /** * Display directories where recent creates took place. */ public class RecentsCreateFragment extends Fragment { private View mEmptyView; private ListView mListView; private DocumentStackAdapter mAdapter; private LoaderCallbacks<List<DocumentStack>> mCallbacks; private static final int LOADER_RECENTS = 3; public static void show(FragmentManager fm) { final RecentsCreateFragment fragment = new RecentsCreateFragment(); final FragmentTransaction ft = fm.beginTransaction(); ft.replace(R.id.container_directory, fragment); ft.commitAllowingStateLoss(); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { final Context context = inflater.getContext(); final View view = inflater.inflate(R.layout.fragment_directory, container, false); mEmptyView = view.findViewById(android.R.id.empty); mListView = (ListView) view.findViewById(R.id.list); mListView.setOnItemClickListener(mItemListener); mAdapter = new DocumentStackAdapter(); mListView.setAdapter(mAdapter); final RootsCache roots = DocumentsApplication.getRootsCache(context); final State state = ((DocumentsActivity) getActivity()).getDisplayState(); mCallbacks = new LoaderCallbacks<List<DocumentStack>>() { @Override public Loader<List<DocumentStack>> onCreateLoader(int id, Bundle args) { return new RecentsCreateLoader(context, roots, state); } @Override public void onLoadFinished(Loader<List<DocumentStack>> loader, List<DocumentStack> data) { mAdapter.swapStacks(data); // When launched into empty recents, show drawer if (mAdapter.isEmpty() && !state.stackTouched) { ((DocumentsActivity) context).setRootsDrawerOpen(true); } } @Override public void onLoaderReset(Loader<List<DocumentStack>> loader) { mAdapter.swapStacks(null); } }; return view; } @Override public void onStart() { super.onStart(); getLoaderManager().restartLoader(LOADER_RECENTS, getArguments(), mCallbacks); } @Override public void onStop() { super.onStop(); getLoaderManager().destroyLoader(LOADER_RECENTS); } private OnItemClickListener mItemListener = new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { final DocumentStack stack = mAdapter.getItem(position); ((DocumentsActivity) getActivity()).onStackPicked(stack); } }; public static class RecentsCreateLoader extends UriDerivativeLoader<Uri, List<DocumentStack>> { private final RootsCache mRoots; private final State mState; public RecentsCreateLoader(Context context, RootsCache roots, State state) { super(context, RecentsProvider.buildRecent()); mRoots = roots; mState = state; } @Override public List<DocumentStack> loadInBackground(Uri uri, CancellationSignal signal) { final Collection<RootInfo> matchingRoots = mRoots.getMatchingRootsBlocking(mState); final ArrayList<DocumentStack> result = Lists.newArrayList(); final ContentResolver resolver = getContext().getContentResolver(); final Cursor cursor = resolver.query(uri, null, null, null, RecentColumns.TIMESTAMP + " DESC", signal); try { while (cursor != null && cursor.moveToNext()) { final byte[] rawStack = cursor.getBlob(cursor.getColumnIndex(RecentColumns.STACK)); try { final DocumentStack stack = new DocumentStack(); DurableUtils.readFromArray(rawStack, stack); // Only update root here to avoid spinning up all // providers; we update the stack during the actual // restore. This also filters away roots that don't // match current filter. stack.updateRoot(matchingRoots); result.add(stack); } catch (IOException e) { Log.w(TAG, "Failed to resolve stack: " + e); } } } finally { //IoUtils.closeQuietly(cursor); IOUtils.closeQuietly(cursor); } return result; } } private class DocumentStackAdapter extends BaseAdapter { private List<DocumentStack> mStacks; public DocumentStackAdapter() { } public void swapStacks(List<DocumentStack> stacks) { mStacks = stacks; if (isEmpty()) { mEmptyView.setVisibility(View.VISIBLE); } else { mEmptyView.setVisibility(View.GONE); } notifyDataSetChanged(); } @Override public View getView(int position, View convertView, ViewGroup parent) { final Context context = parent.getContext(); if (convertView == null) { final LayoutInflater inflater = LayoutInflater.from(context); convertView = inflater.inflate(R.layout.item_doc_list, parent, false); } final ImageView iconMime = (ImageView) convertView.findViewById(R.id.icon_mime); final TextView title = (TextView) convertView.findViewById(android.R.id.title); final View line2 = convertView.findViewById(R.id.line2); final DocumentStack stack = getItem(position); iconMime.setImageDrawable(stack.root.loadIcon(context)); final Drawable crumb = context.getResources().getDrawable(R.drawable.ic_breadcrumb_arrow); crumb.setBounds(0, 0, crumb.getIntrinsicWidth(), crumb.getIntrinsicHeight()); final SpannableStringBuilder builder = new SpannableStringBuilder(); builder.append(stack.root.title); for (int i = stack.size() - 2; i >= 0; i--) { appendDrawable(builder, crumb); builder.append(stack.get(i).displayName); } title.setText(builder); title.setEllipsize(TruncateAt.MIDDLE); if (line2 != null) line2.setVisibility(View.GONE); return convertView; } @Override public int getCount() { return mStacks != null ? mStacks.size() : 0; } @Override public DocumentStack getItem(int position) { return mStacks.get(position); } @Override public long getItemId(int position) { return getItem(position).hashCode(); } } private static void appendDrawable(SpannableStringBuilder b, Drawable d) { final int length = b.length(); b.append("\u232a"); b.setSpan(new ImageSpan(d), length, b.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE); } }