Android 总结三

1、打开raw资源文件

AssetFileDescriptor file = getResources().openRawResourceFd(R.raw.beep);

2、打开assert里的文件

InputStream inputStream = getAssets().open("tangyan.jpg");

3、mediaPlayer的初始化

// 设置声道流格式为音乐setVolumeControlStream(AudioManager.STREAM_MUSIC);MediaPlayer mediaPlayer = new MediaPlayer();mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);//设置声音完成后监听mediaPlayer.setOnCompletionListener(beepListener);AssetFileDescriptor file = getResources().openRawResourceFd(        R.raw.beep);try {    mediaPlayer.setDataSource(file.getFileDescriptor(),            file.getStartOffset(), file.getLength());    file.close();    mediaPlayer.setVolume(BEEP_VOLUME, BEEP_VOLUME);//设置音量    mediaPlayer.prepare();} catch (IOException e) {    mediaPlayer = null;}/** * 当声音播放完成后，播放点回到原点 */private final MediaPlayer.OnCompletionListener beepListener = new MediaPlayer.OnCompletionListener() {    public void onCompletion(MediaPlayer mediaPlayer) {        mediaPlayer.seekTo(0);    }};

4、activity动画切换

overridePendingTransition(R.anim.activity_in_from_rigth, R.anim.activity_out_to_scale);

5、压缩图片

ByteArrayOutputStream baos = new ByteArrayOutputStream();bitmap.compress(Bitmap.CompressFormat.PNG, 100, baos);byte[] bitmapByte = baos.toByteArray();intent.putExtra("bitmap", bitmapByte);

6、显示图片的一段区域

ImageView mImageView = (ImageView) findViewById(R.id.id_imageview);try {    InputStream inputStream = getAssets().open("tangyan.jpg");    //获得图片的宽、高    BitmapFactory.Options tmpOptions = new BitmapFactory.Options();    tmpOptions.inJustDecodeBounds = true;    BitmapFactory.decodeStream(inputStream, null, tmpOptions);    int width = tmpOptions.outWidth;    int height = tmpOptions.outHeight;    //设置显示图片的中心区域    BitmapRegionDecoder bitmapRegionDecoder = BitmapRegionDecoder.newInstance(inputStream, false);    BitmapFactory.Options options = new BitmapFactory.Options();    options.inPreferredConfig = Bitmap.Config.RGB_565;    Bitmap bitmap = bitmapRegionDecoder.decodeRegion(new Rect(width / 2 - 100, height / 2 - 100, width / 2 + 100, height / 2 + 100), options);    mImageView.setImageBitmap(bitmap);} catch (IOException e){    e.printStackTrace();}

7、onTouchEvent里的

getX与getY指的是以当前前控件的左上角所在的坐标为（0，0）原点getX > 0 and getX< getWidthgetY > 0 and getY< getHeight

8、图片缩放的时候必须invalidate();

9、把事件交给手势处理

@Overridepublic boolean onTouch(View v, MotionEvent event) {    if (v == mOriginalImageView) {        mGestureDetector.onTouchEvent(event);        return true;    }    return false;}

10、listview的内容变化了，一定要用notifyDataSetChanged通知

protected void expandOrCollapse(int position) {    Node node = mNodes.get(position);    if (node!= null) {        if (!node.isLeaf()) {            //表示如果关闭的就打开，如果打开的就关闭            node.setExpend(!node.isExpend());            //重新赋值            mNodes = TreeHelper.filterVisibleNode(mAllNodes);            //通知视图改变了            notifyDataSetChanged();        }    }}

11、读取属性文件

TypedArray a = obtainStyledAttributes(R.styleable.NamecardImageGalleryStyle);galleryItemBackground = a.getResourceId(R.styleable.NamecardImageGalleryStyle_android_galleryItemBackground, 0);a.recycle();

12、过滤jpg文件

/**     * 过滤jpg文件     */private class JpgFileFilter implements FilenameFilter {    @Override    public boolean accept(File dir, String filename) {        filename = filename.toLowerCase();         return filename.endsWith(".jpg") || filename.endsWith(".jpeg") ;    }}public class ImageFileFilter implements FileFilter{      @Override      public boolean accept(File pathname) {          String filename = pathname.getName().toLowerCase();          return  filename.endsWith(".jpg")||filename.endsWith(".jpeg");      }  } 

13、得到所有文件

/** * 得到所有文件 * @param path * @return */public static ArrayList<File> getAllFiles(File path) {    ArrayList<File> list = new ArrayList<File>();    // 递归取得目录下的所有文件及文件夹    File[] files = path.listFiles();    for (int i = 0; i < files.length; i++) {        File file = files[i];        list.add(file);        if (file.isDirectory()) {            getAllFiles(file);        }    }    return list;}

14、数组合并

/** * 数组合并 *  * @param strs */public static <T> Object[] addArrays(T[]... strs) {    List<T> list = new ArrayList<T>(Arrays.asList(strs[0]));    for (int i = 1; i < strs.length; i++) {        list.addAll(Arrays.asList(strs[i]));    }    Object[] c = list.toArray();    return c;}

15、读取uri所在的图片

 Bitmap bitmap = MediaStore.Images.Media.getBitmap(this.getContentResolver(), uri); 16、获得图片的宽高 Rect rect = getDrawable().getBounds(); Rect rect = getDrawable().getBounds(); int imageHeight = rect.bottom - rect.top; int imageWidth = rect.right - rect.left;

17、listview移动到位置

 //有动画移动 mListView.smoothScrollToPosition(mLastPoint); //直接定位 listView.setSelection(lastPoint); 18、文件拷贝 // 对List进行排序Comparator<File> comparator = new FileComparator();Collections.sort(tempFolder, comparator);Collections.sort(tempFile, comparator);// 重新整理datas数组中的数据mFiles = new File[tempFolder.size() + tempFile.size()];// 把临时文件夹中的内容添加到mFiles集合中System.arraycopy(tempFolder.toArray(), 0, mFiles, 0, tempFolder.size());// 把临时文件中的内容添加到mFiles集合中,大小是tempFolder.size()增加System.arraycopy(tempFile.toArray(), 0, mFiles, tempFolder.size(), tempFile.size());

19、fragment添加 tabhost

private void addTabFragment() {    ArrayList<TabMode> listTabModes = new ArrayList<TabMode>();    TabMode tabMode = new TabMode(TAB_HOME, R.drawable.tab_1_selector, "首页", R.color.tab_text_color_selector, new TabHomeFragment(),            mCurrentTab == TAB_HOME);    listTabModes.add(tabMode);    tabMode = new TabMode(TAB_SEARCH, R.drawable.tab_2_selector, "好友", R.color.tab_text_color_selector, new TabFriendFragment(),            mCurrentTab == TAB_SEARCH);    listTabModes.add(tabMode);    tabMode = new TabMode(TAB_INFO, R.drawable.tab_3_selector, "通讯录", R.color.tab_text_color_selector, new InfomationFragment(),            mCurrentTab == TAB_INFO);    listTabModes.add(tabMode);    tabMode = new TabMode(TAB_MORE, R.drawable.tab_4_selector, "更多", R.color.tab_text_color_selector, new TabMoreFragment(),            mCurrentTab == TAB_MORE);    listTabModes.add(tabMode);    mTabFragment.creatTab(MainActivity.this, listTabModes, new TabFragment.IFocusChangeListener() {        @Override        public void OnFocusChange(int currentTabId, int tabIndex) {        }    });}

20。退出所有的fragment

int backStackCount = getFragmentManager().getBackStackEntryCount();for (int i = 0; i < backStackCount; i++) {     //弹出堆栈中的一个并且显示，也就是代码模拟按下返回键的操作。    getFragmentManager().popBackStack();}

21、常用自定义属性写法

TypedArray ta = context.obtainStyledAttributes(attrs,              R.styleable.ColorTrackView);  mText = ta.getString(R.styleable.ColorTrackView_text);  mTextSize = ta.getDimensionPixelSize(          R.styleable.ColorTrackView_text_size, mTextSize);  mTextOriginColor = ta.getColor(          R.styleable.ColorTrackView_text_origin_color,          mTextOriginColor);  mTextChangeColor = ta.getColor(          R.styleable.ColorTrackView_text_change_color,          mTextChangeColor);  mProgress = ta.getFloat(R.styleable.ColorTrackView_progress, 0);  mDirection = ta.getInt(R.styleable.ColorTrackView_direction, mDirection);  ta.recycle();  <?xml version="1.0" encoding="utf-8"?>  <resources>      <attr name="text" format="string" />      <attr name="text_size" format="dimension" />      <attr name="text_origin_color" format="color|reference" />      <attr name="text_change_color" format="color|reference" />      <attr name="progress" format="float" />      <attr name="direction">          <enum name="left" value="0" />          <enum name="right" value="1" />      </attr>      <declare-styleable name="ColorTrackView">          <attr name="text" />          <attr name="text_size" />          <attr name="text_origin_color" />          <attr name="text_change_color" />          <attr name="progress" />          <attr name="direction" />      </declare-styleable>  </resources>