Android 图片处理避免出现oom的方法详解

1. 通过设置采样率压缩

res资源图片压缩 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图片压缩 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图片压缩

  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;  }

根据显示的图片大小进行SampleSize的计算

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;  }

调用方式：

复制代码 代码如下: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. 质量压缩：指定图片缩小到xkb以下

  // 压缩到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. 单纯获取图片宽高避免oom的办法

itmapFactory.Options这个类，有一个字段叫做 inJustDecodeBounds 。SDK中对这个成员的说明是这样的：If set to true, the decoder will return null (no bitmap), but the out…

也就是说，如果我们把它设为true，那么BitmapFactory.decodeFile(String path, Options opt)并不会真的返回一个Bitmap给你，它仅仅会把它的宽，高取回来给你，这样就不会占用太多的内存，也就不会那么频繁的发生OOM了。

  /**   * 根据res获取Options，来获取宽高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内容，希望对大家的学习有所帮助，也希望大家多多支持。

成功是什么?就是走过了所有通向失败的路.只剩下一条路.那就是成功的路.