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Android笔记

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将Assets中的文件拷贝到SD卡中

有时候需要将Assets中的资源共享给其他应用，但是Assets实际是在APK包体内，无法直接传递路径，这时就需要将文件复制到一个可以公共存取的地方。

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private void copyBigDataToSD(String strOutFileName) throws IOException {  
    InputStream myInput;  
    String outpath = Environment. getExternalStoragePublicDirectory( Environment.DIRECTORY_PICTURES ) + "/" + strOutFileName;
    OutputStream myOutput = new FileOutputStream( outpath );  
    myInput = mActivity.getAssets().open( strOutFileName );  
    byte[] buffer = new byte[1024];  
    int length = myInput.read(buffer);
    while(length > 0)
    {
        myOutput.write(buffer, 0, length); 
        length = myInput.read(buffer);
    }            
    myOutput.flush();  
    myInput.close();  
    myOutput.close();        
}

获得屏幕快照 Screenshot

用于游戏截图，但需要注意：如果有应用中使用了GLSurfaceView，那这个就不好使了，会得到黑色的截图。

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private void takeScreenshot( String filename ) {
  try {
      // image naming and path  to include sd card  appending name you choose for file
      String mPath = Environment. getExternalStoragePublicDirectory( Environment.DIRECTORY_PICTURES ) + "/" + filename + ".jpg";

      // create bitmap screen capture
      View v1 = mActivity.getWindow().getDecorView().getRootView();
      v1.setDrawingCacheEnabled(true);
      Bitmap bitmap = Bitmap.createBitmap(v1.getDrawingCache());
      v1.setDrawingCacheEnabled(false);

      File imageFile = new File(mPath);

      FileOutputStream outputStream = new FileOutputStream(imageFile);
      int quality = 100;
      bitmap.compress(Bitmap.CompressFormat.JPEG, quality, outputStream);
      outputStream.flush();
      outputStream.close();

      openScreenshot(imageFile);
  } catch (Throwable e) {
      // Several error may come out with file handling or OOM
      e.printStackTrace();
  }
}
  
//此方法调用图片查看器查看图片
private void openScreenshot(File imageFile) {
  Intent intent = new Intent();
  intent.setAction(Intent.ACTION_VIEW);
  Uri uri = Uri.fromFile(imageFile);
  intent.setDataAndType(uri, "image/*");
  mActivity.startActivity(intent);
}

利用ACTION_SEND实现分享功能

利用支持ACTION_SEND的应用分享内容。

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public void Share( ) {
  Intent sendIntent = new Intent();
  sendIntent.setAction(Intent.ACTION_SEND);
  sendIntent.putExtra(Intent.EXTRA_SUBJECT, "Title Of The Post"); //标题
  sendIntent.putExtra(Intent.EXTRA_TEXT, "http://www.google.com"); //内容
  
  //分享Assets内的图片
  String img_path = "splash.jpg";
  try {
    copyBigDataToSD( img_path ); //将Assets中的图片复制到SD卡中 这样使其他的应用可以读取
  } catch (IOException e) {
    e.printStackTrace();
  }
  String imagePath = Environment. getExternalStoragePublicDirectory( Environment.DIRECTORY_PICTURES ) + "/" + img_path;
  File imageFileToShare = new File(imagePath);
  Uri uri = Uri.fromFile(imageFileToShare);
  sendIntent.putExtra(Intent.EXTRA_STREAM, uri); //只接受URI
  
  //这个设置会影响应用筛选的结果
  //sendIntent.setType("text/plain");
  sendIntent.setType("image/jpeg");
  
  mActivity.startActivityForResult( Intent.createChooser( sendIntent, "Share to" ), 0 );
}

保持屏幕不暗不关闭的官方推荐方法

调用 keepScrrenOn() 函数后，在当前Activity可见的情况下保持屏幕不暗不灭。

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// Sets the flag to keep this screen on. It's recommended to do that during
// the
// handshake when setting up a game, because if the screen turns off, the
// game will be
// cancelled.
void keepScreenOn() {
  getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
}

// Clears the flag that keeps the screen on.
void stopKeepingScreenOn() {
  getWindow().clearFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
}