Android圖片實現(xiàn)壓縮處理的實例代碼

 //進(jìn)行大小縮放來達(dá)到壓縮的目的
 BitmapFactory.Options options = new BitmapFactory.Options();
 options.inJustDecodeBounds = true;
 BitmapFactory.decodeFile(srcImagePath, options);
 //根據(jù)原始圖片的寬高比和期望的輸出圖片的寬高比計算最終輸出的圖片的寬和高

 float srcWidth = options.outWidth;
 float srcHeight = options.outHeight;
 float maxWidth = outWidth;
 float maxHeight = outHeight;
 float srcRatio = srcWidth / srcHeight; //原始圖片寬高比
 float outRatio = maxWidth / maxHeight; //目標(biāo)圖片寬高比
 float actualOutWidth = srcWidth;
 float actualOutHeight = srcHeight;
  if (srcWidth > maxWidth || srcHeight > maxHeight) {
   if(srcRatio>outRatio){ //原始寬高比大于目標(biāo)寬高比
     actualOutWidth = maxWidth;
     actualOutHeight = actualOutWidth / srcRatio;
   }else if(srcRatio<outRatio){ //原始寬高比小于目標(biāo)寬高比
     actualOutHeight = maxHeight;
     actualOutWidth = actualOutHeight * srcRatio;
   }
 }else{
   actualOutWidth = maxWidth;
   actualOutHeight = maxHeight;
 }

 options.inSampleSize = computSampleSize(options, actualOutWidth, actualOutHeight);
 options.inJustDecodeBounds = false;
 Bitmap scaledBitmap = null;
 try {
   scaledBitmap = BitmapFactory.decodeFile(srcImagePath, options);
 } catch (OutOfMemoryError e) {
   e.printStackTrace();
 }
 if (scaledBitmap == null) {
   return null;
 }

  //生成最終輸出的bitmap
 Bitmap actualOutBitmap = Bitmap.createScaledBitmap(scaledBitmap, (int) actualOutWidth, (int) actualOutHeight, true);

 //釋放原始位圖資源
 if(scaledBitmap!=actualOutBitmap){ //判斷目標(biāo)位圖是否和原始位圖指向棧目標(biāo)相同
   scaledBitmap.recycle();
   scaledBitmap = null;
 }

  //處理圖片旋轉(zhuǎn)問題
 ExifInterface exif = null;
 try {
   exif = new ExifInterface(srcImagePath);
   int orientation = exif.getAttributeInt(
       ExifInterface.TAG_ORIENTATION, 0);
   Matrix matrix = new Matrix();
   if (orientation == ExifInterface.ORIENTATION_ROTATE_90) {
     matrix.postRotate(90);
   } else if (orientation == ExifInterface.ORIENTATION_ROTATE_180) {
     matrix.postRotate(180);
   } else if (orientation == ExifInterface.ORIENTATION_ROTATE_270) {
     matrix.postRotate(270);
   }
   actualOutBitmap = Bitmap.createBitmap(actualOutBitmap, 0, 0,
       actualOutBitmap.getWidth(), actualOutBitmap.getHeight(), matrix, true);
 } catch (IOException e) {
   e.printStackTrace();
   return null;
 }

  //進(jìn)行有損壓縮
 ByteArrayOutputStream baos = new ByteArrayOutputStream();
 int options_ = 100;
 actualOutBitmap.compress(Bitmap.CompressFormat.JPEG, options_, baos);//質(zhì)量壓縮方法，把壓縮后的數(shù)據(jù)存放到baos中 (100表示不壓縮，0表示壓縮到最小)

 int baosLength = baos.toByteArray().length;

 while (baosLength / 1024 > maxFileSize) {//循環(huán)判斷如果壓縮后圖片是否大于maxMemmorrySize,大于繼續(xù)壓縮
   baos.reset();//重置baos即讓下一次的寫入覆蓋之前的內(nèi)容
   options_ = Math.max(0, options_ - 10);//圖片質(zhì)量每次減少10
   actualOutBitmap.compress(Bitmap.CompressFormat.JPEG, options_, baos);//將壓縮后的圖片保存到baos中
   baosLength = baos.toByteArray().length;
   if (options_ == 0)//如果圖片的質(zhì)量已降到最低則，不再進(jìn)行壓縮
     break;
 }
 actualOutBitmap.recycle();

 //將bitmap保存到指定路徑
 FileOutputStream fos = null;
 String filePath = getOutputFileName(srcImagePath);
 try {
   fos = new FileOutputStream(filePath);
   //包裝緩沖流,提高寫入速度
   BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(fos);
   bufferedOutputStream.write(baos.toByteArray());
   bufferedOutputStream.flush();
 } catch (FileNotFoundException e) {
   return null;
 } catch (IOException e) {
   return null;
 } finally {
   if (baos != null) {
     try {
       baos.close();
     } catch (IOException e) {
       e.printStackTrace();
     }
   }
   if (fos != null) {
     try {
       fos.close();
     } catch (IOException e) {
       e.printStackTrace();
     }
   }
 }

 //獲取位圖縮放比例
 private int computSampleSize(BitmapFactory.Options options, float reqWidth, float reqHeight) {
   float srcWidth = options.outWidth;//20
   float srcHeight = options.outHeight;//10
   int sampleSize = 1;
   if (srcWidth > reqWidth || srcHeight > reqHeight) {
     int withRatio = Math.round(srcWidth / reqWidth);
     int heightRatio = Math.round(srcHeight / reqHeight);
     sampleSize = Math.min(withRatio, heightRatio);
   }
   return sampleSize;
 }

float srcWidth = options.outWidth;
float srcHeight = options.outHeight;
float widthScale = outWidth / srcWidth;//目標(biāo)/原始 寬比例
float heightScale = outHeight / srcHeight; //目標(biāo)原始 高比
//對比寬高比選擇較大的一種比例
float scale = widthScale > heightScale ? widthScale : heightScale;
float actualOutWidth = srcWidth;
float actualOutHeight = srcHeight;
if (scale < 1) {
  actualOutWidth = srcWidth * scale;
  actualOutHeight = srcHeight * scale;
}

  Matrix matrix1 = new Matrix();
  matrix1.postScale(scale, scale);// 放大縮小比例
  //生成最終輸出的bitmap
  Bitmap actualOutBitmap = Bitmap.createBitmap(scaledBitmap, 0, 0, scaledBitmap.getWidth(), scaledBitmap.getHeight(), matrix1, true);

  if (actualOutBitmap != scaledBitmap) {
    scaledBitmap.recycle();
    scaledBitmap = null;
    System.gc();
  }