图片压缩那些事

//判断照片角度
private final static int getDegress(String path) {
int degree = 0;
try {
ExifInterface exifInterface = new ExifInterface(path);
int orientation = exifInterface.getAttributeInt(
ExifInterface.TAG_ORIENTATION,
ExifInterface.ORIENTATION_NORMAL);
switch (orientation) {
case ExifInterface.ORIENTATION_ROTATE_90:
degree = 90;
break;
case ExifInterface.ORIENTATION_ROTATE_180:
degree = 180;
break;
case ExifInterface.ORIENTATION_ROTATE_270:
degree = 270;
break;
}
} catch (IOException e) {
e.printStackTrace();
}
return degree;
}

/**
* rotate the bitmap
* @param bitmap
* @param degress
* @return
*/
private static Bitmap rotateBitmap(Bitmap bitmap, int degress) {
if (bitmap != null) {
Matrix m = new Matrix();
m.postRotate(degress);
bitmap = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), m, true);
return bitmap;
}
return bitmap;
}

/**
* 压缩指定路径图片，并将其保存在缓存目录中，通过isDelSrc判定是否删除源文件，并获取到缓存后的图片路径
* @param context
* @param srcPath
* @param isDelSrc
* @return
*/
public final static String compressBitmap(Context context, String srcPath, boolean isDelSrc) {
Bitmap bitmap = compressImage(srcPath);
File srcFile = new File(srcPath);
String desPath = "";
int degree = getDegress(srcPath);
try {
if (degree != 0) bitmap = rotateBitmap(bitmap, degree);
File file = new File("新路径"+srcFile.getName());
desPath = file.getPath();
FileOutputStream  fos = new FileOutputStream(file);
if(srcPath.toLowerCase().endsWith("png"))
bitmap.compress(Bitmap.CompressFormat.PNG, 50, fos);//把压缩后的数据存放到baos中
else
bitmap.compress(Bitmap.CompressFormat.JPEG, 50, fos);
fos.close();
if (isDelSrc) srcFile.deleteOnExit();
} catch (Exception e) {
Log.e("BitmapHelper-->compressBitmap", e.getMessage()+"");
}
return desPath;
}

/**
* 基于质量的压缩算法， 此方法未 解决压缩后图像失真问题
* <br> 可先调用比例压缩适当压缩图片后，再调用此方法可解决上述问题
* @param bts
* @param maxBytes 压缩后的图像最大大小 单位为byte
* @return
*/
public final static Bitmap compressImage(Bitmap image, long maxBytes) {
try {
int options = 100;
ByteArrayOutputStream baos = new ByteArrayOutputStream();
image.compress(Bitmap.CompressFormat.JPEG, options, baos);//质量压缩方法，这里100表示不压缩，把压缩后的数据存放到baos中
while ( baos.toByteArray().length/1024 > maxBytes) {//循环判断如果压缩后图片是否大maxByteskb,大于继续压缩
baos.reset();//重置baos即清空baos
options -= 10;//每次都减少10
image.compress(Bitmap.CompressFormat.JPEG, options, baos);//这里压缩options%，把压缩后的数据存放到baos中
}
byte[] bts = baos.toByteArray();
Bitmap bmp = BitmapFactory.decodeByteArray(bts, 0, bts.length);
return bmp;
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
/**
* 按照图片的比例进行压缩
* @param srcPath
* @return
*/
public final static Bitmap compressImage(String srcPath) {
BitmapFactory.Options newOpts = new BitmapFactory.Options();
//开始读入图片，此时把options.inJustDecodeBounds 设回true了
newOpts.inJustDecodeBounds = true;
Bitmap bitmap = BitmapFactory.decodeFile(srcPath,newOpts);
newOpts.inJustDecodeBounds = false;
int w = newOpts.outWidth;
int h = newOpts.outHeight;
float reqHeight = 800f;//这里设置高度为800f
float reqWidth = 480f;//这里设置宽度为480f
//缩放比。由于是固定比例缩放，只用高或者宽其中一个数据进行计算即可
int inSampleSize = 1;
if (h > reqHeight || w > reqWidth) {
final int heightRatio = Math.round((float) h/ (float) reqHeight);
final int widthRatio = Math.round((float) w / (float) reqWidth);
inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
}
if (inSampleSize <= 0)
inSampleSize = 1;
newOpts.inSampleSize = inSampleSize;//设置缩放比例
//重新读入图片，注意此时已经把options.inJustDecodeBounds 设回false了
bitmap = BitmapFactory.decodeFile(srcPath, newOpts);
if(bitmap != null && !srcPath.toLowerCase().endsWith("png"))//png格式的图片不能进行质量压缩
bitmap = compressImage(bitmap,100);//压缩好比例大小后再进行质量压缩
return bitmap;
}