android的照相

android的照相功能随着手机硬件的发展，变得越来越强大，能够找出很高分辨率的图片。
有些场景中，需要照相并且上传到服务，但是由于图片的大小太大，那么就上传就会很慢(在有些网络情况下)，而且很耗流量，要想速度快，那么就需要减小图片的大小。减少图片的大小有两种方法，1. 照小图片； 2. 压缩大图片。 照相时获取小图片一般不太符合要求，因为，图片的清晰度会很差，但是这种情况有个好处就是应用速度会快些； 压缩图片，就是把大图片压缩小，降低图片的质量，在一定范围内，降低图片的大小，并且满足需求（图片仍就清晰）。下面组要是介绍图片的压缩：

1. 照相请查看http://www.jb51.net/article/37760.htm ->想要保存图片到制定目录，启动Camera应用时，需要指定文件
2. 压缩过程：
   2.1 从图片路径中读取图片(图片很大，不能全部加在到内存中处理，要是全部加载到内存中会内存溢出)
   [java]
   复制代码 代码如下:

final BitmapFactory.Options options = new BitmapFactory.Options();     options.inJustDecodeBounds = true;     BitmapFactory.decodeFile(filePath, options);     // Calculate inSampleSize      options.inSampleSize = calculateInSampleSize(options, 480, 800);     // Decode bitmap with inSampleSize set      options.inJustDecodeBounds = false;     Bitmap bm = BitmapFactory.decodeFile(filePath, options); final BitmapFactory.Options options = new BitmapFactory.Options();  options.inJustDecodeBounds = true;  BitmapFactory.decodeFile(filePath, options);  // Calculate inSampleSize  options.inSampleSize = calculateInSampleSize(options, 480, 800);  // Decode bitmap with inSampleSize set  options.inJustDecodeBounds = false;  Bitmap bm = BitmapFactory.decodeFile(filePath, options);

2.2 处理图片旋转
[java]
复制代码 代码如下:

int degree = readPictureDegree(filePath);         bm = rotateBitmap(bm,degree) ;int degree = readPictureDegree(filePath);  bm = rotateBitmap(bm,degree) ;[java] view plaincopyprint?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;                      }              } catch (IOException e) {                      e.printStackTrace();              }              return degree;          } 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;                 }         } catch (IOException e) {                 e.printStackTrace();         }         return degree;     }

[java]
复制代码 代码如下:

view plaincopyprint?private static Bitmap rotateBitmap(Bitmap bitmap, int rotate){        if(bitmap == null)             return null ;         int w = bitmap.getWidth();         int h = bitmap.getHeight();         // Setting post rotate to 90          Matrix mtx = new Matrix();         mtx.postRotate(rotate);         return Bitmap.createBitmap(bitmap, 0, 0, w, h, mtx, true);     }private static Bitmap rotateBitmap(Bitmap bitmap, int rotate){  if(bitmap == null)   return null ;  int w = bitmap.getWidth();  int h = bitmap.getHeight();  // Setting post rotate to 90  Matrix mtx = new Matrix();  mtx.postRotate(rotate);  return Bitmap.createBitmap(bitmap, 0, 0, w, h, mtx, true); }

2.3压缩图片
[java]
复制代码 代码如下:

bm.compress(Bitmap.CompressFormat.JPEG, 30, baos);//30 是压缩率，表示压缩70%; 如果不压缩是100，表示压缩率为0
bm.compress(Bitmap.CompressFormat.JPEG, 30, baos);//30 是压缩率，表示压缩70%; 如果不压缩是100，表示压缩率为0

完整的方法代码：
[java]
复制代码 代码如下:

public static Bitmap getSmallBitmap(String filePath) {         final BitmapFactory.Options options = new BitmapFactory.Options();         options.inJustDecodeBounds = true;         BitmapFactory.decodeFile(filePath, options);         // Calculate inSampleSize          options.inSampleSize = calculateInSampleSize(options, 480, 800);         // Decode bitmap with inSampleSize set          options.inJustDecodeBounds = false;         Bitmap bm = BitmapFactory.decodeFile(filePath, options);         if(bm == null){             return  null;         }         int degree = readPictureDegree(filePath);         bm = rotateBitmap(bm,degree) ;         ByteArrayOutputStream baos = null ;         try{             baos = new ByteArrayOutputStream();             bm.compress(Bitmap.CompressFormat.JPEG, 30, baos);         }finally{             try {                 if(baos != null)                     baos.close() ;             } catch (IOException e) {                 e.printStackTrace();             }         }         return bm ;     }public static Bitmap getSmallBitmap(String filePath) {  final BitmapFactory.Options options = new BitmapFactory.Options();  options.inJustDecodeBounds = true;  BitmapFactory.decodeFile(filePath, options);  // Calculate inSampleSize  options.inSampleSize = calculateInSampleSize(options, 480, 800);  // Decode bitmap with inSampleSize set  options.inJustDecodeBounds = false;  Bitmap bm = BitmapFactory.decodeFile(filePath, options);  if(bm == null){   return  null;  }  int degree = readPictureDegree(filePath);  bm = rotateBitmap(bm,degree) ;  ByteArrayOutputStream baos = null ;  try{   baos = new ByteArrayOutputStream();   bm.compress(Bitmap.CompressFormat.JPEG, 30, baos);  }finally{   try {    if(baos != null)     baos.close() ;   } catch (IOException e) {    e.printStackTrace();   }  }  return bm ; }

[java]
复制代码 代码如下:

view plaincopyprint?private static int calculateInSampleSize(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) {             // Calculate ratios of height and width to requested height and              // width              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;     }private static int calculateInSampleSize(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) {   // Calculate ratios of height and width to requested height and   // width   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; }