簡介：最近在做圖片上傳的相關功能，需要對圖片的大小和尺寸進行壓縮處理。
好處：（1）提升性能（2）節省流量
一、圖片大小循環壓縮
/**
* 壓縮圖片文件到指定大小
*
* @param filePath
*/
public static void compressBmpToFile(String filePath) {
Bitmap bitmap = BitmapFactory.decodeFile(filePath);
if (null == bitmap) {
return;
}
final int BYTE_LEN = 1024;
//文件最大爲200KB
final int MAX_FILE_SIZE = 256;
final ByteArrayOutputStream baos = new ByteArrayOutputStream();
int quality = 90;
bitmap.compress(Bitmap.CompressFormat.JPEG, quality, baos);
while (baos.toByteArray().length / BYTE_LEN > MAX_FILE_SIZE) {
baos.reset();
quality -= 10;
bitmap.compress(Bitmap.CompressFormat.JPEG, quality, baos);
float size = calculteBitmapSize(bitmap);
}
try {
final FileOutputStream fos = new FileOutputStream(new File(filePath));
fos.write(baos.toByteArray());
fos.flush();
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 計算bitmap的大小
*
* @param bitmap
* @return bitmap的大小單位KB
*/
public static float calculteBitmapSize(Bitmap bitmap) {
if (null == bitmap) {
return 0.0f;
}
final ByteArrayOutputStream baos = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, baos);
final float size = (baos.toByteArray().length / 1024);
try {
baos.close();
} catch (IOException e) {
e.printStackTrace();
}
return size;
}二、圖片尺寸壓縮
/**
* 壓縮圖片的尺寸
*
* @param srcPath
* @return
*/
public static Bitmap compressImageFromFile(String srcPath) {
final BitmapFactory.Options newOpts = new BitmapFactory.Options();
//只讀邊,不讀內容
newOpts.inJustDecodeBounds = true;
// 獲取這個圖片的寬和高，注意此處的bitmap爲null
BitmapFactory.decodeFile(srcPath, newOpts);
newOpts.inJustDecodeBounds = false;
int w = newOpts.outWidth;
int h = newOpts.outHeight;
float hh = 800f;
float ww = 480f;
int be = 1;
if (w > h && w > ww) {
be = (int) (newOpts.outWidth / ww);
} else if (w < h && h > hh) {
be = (int) (newOpts.outHeight / hh);
}
if (be <= 0) {
be = 1;
}
//設置採樣率
newOpts.inSampleSize = be;
//該模式是默認的,可不設
newOpts.inPreferredConfig = Bitmap.Config.RGB_565;
// 同時設置纔會有效
newOpts.inPurgeable = true;
//當系統內存不夠時候圖片自動被回收
newOpts.inInputShareable = true;
final Bitmap bitmap = BitmapFactory.decodeFile(srcPath, newOpts);
return bitmap;
}