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Android 圖片處理避免出現(xiàn)oom的方法詳解

 更新時間：2017年09月11日 14:16:06   作者：燊在錦官城_  
本篇文章主要介紹了Android 圖片處理避免出現(xiàn)oom的方法詳解，具有一定的參考價值，感興趣的小伙伴們可以參考一下

1. 通過設(shè)置采樣率壓縮

res資源圖片壓縮 decodeResource

  public Bitmap decodeSampledBitmapFromResource(Resources res, int resId, int reqWidth, int reqHeight) {
    // First decode with inJustDecodeBounds=true to check dimensions
    final BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeResource(res, resId, options);

    // Calculate inSampleSize
    options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

    // Decode bitmap with inSampleSize set
    options.inJustDecodeBounds = false;
    return BitmapFactory.decodeResource(res, resId, options);
  }

uri圖片壓縮 decodeStream

  public Bitmap decodeSampledBitmapFromUri(Uri uri, int reqWidth, int reqHeight) {
    Bitmap bitmap = null;
    try {
    BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeStream(getContentResolver().openInputStream(uri), null, options);
    options.inSampleSize = BitmapUtils.calculateInSampleSize(options,
        UtilUnitConversion.dip2px(MyApplication.mContext, reqWidth), UtilUnitConversion.dip2px(MyApplication.mContext, reqHeight));
    options.inJustDecodeBounds = false;

    bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(uri), null, options);
    } catch (Exception e) {
      e.printStackTrace();
    }
    return bitmap;
  }

本地File url圖片壓縮

  public static Bitmap getloadlBitmap(String load_url, int width, int height) {
    Bitmap bitmap = null;
    if (!UtilText.isEmpty(load_url)) {
      File file = new File(load_url);
      if (file.exists()) {
        FileInputStream fs = null;
        try {
          fs = new FileInputStream(file);
        } catch (FileNotFoundException e) {
          e.printStackTrace();
        }
        if (null != fs) {
          try {
            BitmapFactory.Options opts = new BitmapFactory.Options();
            opts.inJustDecodeBounds = true;
            BitmapFactory.decodeFileDescriptor(fs.getFD(), null, opts);
            opts.inDither = false;
            opts.inPurgeable = true;
            opts.inInputShareable = true;
            opts.inTempStorage = new byte[32 * 1024];
            opts.inSampleSize = BitmapUtils.calculateInSampleSize(opts,
                UtilUnitConversion.dip2px(MyApplication.mContext, width), UtilUnitConversion.dip2px(MyApplication.mContext, height));
            opts.inJustDecodeBounds = false;

            bitmap = BitmapFactory.decodeFileDescriptor(fs.getFD(),
                null, opts);
          } catch (IOException e) {
            e.printStackTrace();
          } finally {
            if (null != fs) {
              try {
                fs.close();
              } catch (IOException e) {
                e.printStackTrace();
              }
            }
          }
        }
      }
    }
    return bitmap;
  }

根據(jù)顯示的圖片大小進行SampleSize的計算

public int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
    if (reqWidth == 0 || reqHeight == 0) {
      return 1;
    }

    // Raw height and width of image
    final int height = options.outHeight;
    final int width = options.outWidth;
    int inSampleSize = 1;

    if (height > reqHeight || width > reqWidth) {
      final int halfHeight = height / 2;
      final int halfWidth = width / 2;

      // Calculate the largest inSampleSize value that is a power of 2 and
      // keeps both height and width larger than the requested height and width.
      while ((halfHeight / inSampleSize) >= reqHeight && (halfWidth / inSampleSize) >= reqWidth) {
        inSampleSize *= 2;
      }
    }

    return inSampleSize;
  }

調(diào)用方式：

復(fù)制代碼 代碼如下:

mImageView.setImageBitmap(decodeSampledBitmapFromResource(getResources(), R.id.myImage, 100, 100))

Bitmap bitmap = decodeSampledBitmapFromUri(cropFileUri);
UtilBitmap.setImageBitmap(mContext, mImage,
        UtilBitmap.getloadlBitmap(url, 100, 100),
        R.drawable.ic_login_head, true);

2. 質(zhì)量壓縮：指定圖片縮小到xkb以下

  // 壓縮到100kb以下
  int maxSize = 100 * 1024;
  public static Bitmap getBitmapByte(Bitmap oriBitmap, int maxSize) {
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    oriBitmap.compress(Bitmap.CompressFormat.JPEG, 100, out);

    byte[] fileBytes = out.toByteArray();

    int be = (maxSize * 100) / fileBytes.length;

    if (be > 100) {
      be = 100;
    }
    out.reset();
    oriBitmap.compress(Bitmap.CompressFormat.JPEG, be, out);
    return oriBitmap;
  }

3. 單純獲取圖片寬高避免oom的辦法

itmapFactory.Options這個類，有一個字段叫做 inJustDecodeBounds 。SDK中對這個成員的說明是這樣的：
If set to true, the decoder will return null (no bitmap), but the out...

也就是說，如果我們把它設(shè)為true，那么BitmapFactory.decodeFile(String path, Options opt)并不會真的返回一個Bitmap給你，它僅僅會把它的寬，高取回來給你，這樣就不會占用太多的內(nèi)存，也就不會那么頻繁的發(fā)生OOM了。

  /**
   * 根據(jù)res獲取Options，來獲取寬高outWidth和options.outHeight
   * @param res
   * @param resId
   * @return
   */
  public static BitmapFactory.Options decodeOptionsFromResource(Resources res, int resId) {
    // First decode with inJustDecodeBounds=true to check dimensions
    final BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeResource(res, resId, options);
    return options;
  }

以上就是本文的全部內(nèi)容，希望對大家的學(xué)習(xí)有所幫助，也希望大家多多支持腳本之家。

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