Android图片处理-图片压缩处理

/***
* 这个是调用android内置的intent，来过滤图片文件 ，同时也可以过滤其他的
*/
Intent intent = new Intent();
intent.setType("image/*");
intent.setAction(Intent.ACTION_GET_CONTENT);
startActivityForResult(intent, 1);

if (resultCode == Activity.RESULT_OK) {
Uri uri = data.getData();
try {
String[] pojo = { MediaStore.Images.Media.DATA };

Cursor cursor = managedQuery(uri, pojo, null, null, null);
if (cursor != null) {
ContentResolver cr = this.getContentResolver();
int colunm_index = cursor
.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
cursor.moveToFirst();
String path = cursor.getString(colunm_index);
/***
* 这里加这样一个判断主要是为了第三方的软件选择，比如：使用第三方的文件管理器的话，你选择的文件就不一定是图片了，
* 这样的话，我们判断文件的后缀名 如果是图片格式的话，那么才可以
*/
if (path.endsWith("jpg") || path.endsWith("png")) {
picPath = path;
Bitmap bitmap = PictureUtil.getSmallBitmap(picPath,480,320,50);
//
imageShow.setImageBitmap(bitmap);
//这里更新发布分享按键的可点出状态
btnSubmit.setEnabled(true);

} else {
alert();
}
} else {
alert();
}
} catch (Exception e) {
}
}

/**
* @Description 调用系统拍照或进入图库中选择照片,再进行裁剪,压缩.
* @author chq
*/
public class PictureUtil {
//加载并显示一副图像对内存使用情况有显著的影响，Android提供了一个名为BitmapFactory 的实用程序类，该程序提供了一系列的静态方法，允许通过各种来源加载Bitmap图像。针对我们的需求，将从文件加载图像，并在最初的活动中显示它。幸运的是，BitmapFactory中的可用方法将会调用BitmapFactory.Options类，这使得我们能够定义如何将Bitmap读入内存。具体而言，当加载图像时，可以设置BitmapFactory应该使用的采样大小。在BitmapFactory.Options中指定inSampleSize参数。例如，将inSampleSize
//= 8时，产生一幅图的大小是原始大小的1/8。要注意的是首先应将BitmapFactoryOptions.inJustDecodeBounds变量设置为true,这将通知BitmapFactory类只需返回该图像的范围，而无需尝试解码图像本身。最后将BitmapFactory.Options.inJustDecodeBounds设置为false，最后对其进行真正的解码。
/**
*
* @param picPath
* @param reqWidth
* @param reqHeight
* @param compress
* @return
*/
public static Bitmap getSmallBitmap(String picPath,int reqWidth,int reqHeight,int compress) {
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(picPath, options);  //options中将获得图片一些信息
options.inSampleSize = calulateInSampleSize(options, reqWidth, reqHeight);
options.inJustDecodeBounds = false;

Bitmap bitmap = BitmapFactory.decodeFile(picPath, options);
if (bitmap == null) {
return null;
}
int degree = readPictureDegree(picPath);
bitmap = rotateBitmap(bitmap, degree);
ByteArrayOutputStream baos = null;
try {
baos = new ByteArrayOutputStream();
//压缩图片质量
bitmap.compress(Bitmap.CompressFormat.JPEG,compress, baos);
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if(baos != null) {
baos.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
return bitmap;
}

private static int calulateInSampleSize(BitmapFactory.Options options,int reqWidth,int reqHeight) {
//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 heightRatio = Math.round((float)height / (float)reqHeight);
final int widthRatio = Math.round((float)width / (float)reqWidth);
// Choose the smallest ratio as inSampleSize value, this will
// guarantee
// a final image with both dimensions larger than or equal to the
// requested height and width.
inSampleSize = heightRatio < widthRatio ? widthRatio : heightRatio;
}
return inSampleSize;
}

/**
* 读取图片旋转处理
* @param path
* @return
*/
private static int readPictureDegree(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;
default:
break;
}
} catch (IOException e) {
e.printStackTrace();
}
return degree;
}
/**
* 图片旋转处理
* @param bitmap
* @param rotate
* @return
*/
private static Bitmap rotateBitmap(Bitmap bitmap,int rotate) {
if(bitmap == null) {
return null;
}
int w = bitmap.getWidth();
int h = bitmap.getHeight();
Matrix mtx = new Matrix();
mtx.postRotate(rotate);
return Bitmap.createBitmap(bitmap,0,0,w,h,mtx,true);
}
}