java.lang.OutOfMemoryError: bitmap size exceeds VM budget解决方法
Posted on 2012-05-26 10:23 XiYO 阅读(6235) 评论(0) 编辑 收藏 举报
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BitmapFactory.decodeFile(imageFile); |
用BitmapFactory解码一张图片时,有时会遇到该错误。这往往是由于图片过大造成的。要想正常使用,则需要分配更少的内存空间来存储。
BitmapFactory.Options.inSampleSize
设置恰当的inSampleSize可以使BitmapFactory分配更少的空间以消除该错误。inSampleSize的具体含义请参考SDK文档。例如:
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BitmapFactory.Options opts = new BitmapFactory.Options(); opts.inSampleSize = 4 ; Bitmap bitmap = BitmapFactory.decodeFile(imageFile, opts); |
如何设置恰当的inSampleSize
设置恰当的inSampleSize是解决该问题的关键之一。BitmapFactory.Options提供了另一个成员inJustDecodeBounds。
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BitmapFactory.Options opts = new BitmapFactory.Options(); opts.inJustDecodeBounds = true ; Bitmap bitmap = BitmapFactory.decodeFile(imageFile, opts); |
设置inJustDecodeBounds为true后,decodeFile并不分配空间,但可计算出原始图片的长度和宽度,即opts.width和opts.height。有了这两个参数,再通过一定的算法,即可得到一个恰当的inSampleSize。
查看Android源码,Android提供了一种动态计算的方法。
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public static int computeSampleSize(BitmapFactory.Options options, int minSideLength, int maxNumOfPixels) { int initialSize = computeInitialSampleSize(options, minSideLength, maxNumOfPixels); int roundedSize; if (initialSize <= 8 ) { roundedSize = 1 ; while (roundedSize < initialSize) { roundedSize <<= 1 ; } } else { roundedSize = (initialSize + 7 ) / 8 * 8 ; } return roundedSize; } private static int computeInitialSampleSize(BitmapFactory.Options options, int minSideLength, int maxNumOfPixels) { double w = options.outWidth; double h = options.outHeight; int lowerBound = (maxNumOfPixels == - 1 ) ? 1 : ( int ) Math.ceil(Math.sqrt(w * h / maxNumOfPixels)); int upperBound = (minSideLength == - 1 ) ? 128 : ( int ) Math.min(Math.floor(w / minSideLength), Math.floor(h / minSideLength)); if (upperBound < lowerBound) { // return the larger one when there is no overlapping zone. return lowerBound; } if ((maxNumOfPixels == - 1 ) && (minSideLength == - 1 )) { return 1 ; } else if (minSideLength == - 1 ) { return lowerBound; } else { return upperBound; } } |
使用该算法,就可动态计算出图片的inSampleSize。
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BitmapFactory.Options opts = new BitmapFactory.Options(); opts.inJustDecodeBounds = true ; BitmapFactory.decodeFile(imageFile, opts); opts.inSampleSize = computeSampleSize(opts, - 1 , 128 * 128 ); opts.inJustDecodeBounds = false ; try { Bitmap bmp = BitmapFactory.decodeFile(imageFile, opts); imageView.setImageBitmap(bmp); } catch (OutOfMemoryError err) { } |
另外,可以通过Bitmap.recycle()方法来释放位图所占的空间,当然前提是位图没有被使用。
获取缩略图关键代码
byte[] imageByte=getImageFromURL(urlPath[i].trim());
//以下是把图片转化为缩略图再加载
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true; //首先设置.inJustDecodeBounds为true
Bitmap bitmap=BitmapFactory.decodeByteArray(imageByte, 0, imageByte.length, options); //这时获取到的bitmap是null的,尚未调用系统内存资源
options.inJustDecodeBounds = false; 得到图片有宽和高的options对象后,设置.inJustDecodeBounds为false。
int be = (int)(options.outHeight / (float)200);
if (be <= 0) be = 1;
options.inSampleSize = be; //计算得到图片缩小倍数
bitmaps[i]=BitmapFactory.decodeByteArray(imageByte, 0, imageByte.length,options); //获取真正的图片对象(缩略图)
/**
* 根据图片网络地址获取图片的byte[]类型数据
* @param urlPath 图片网络地址
* @return 图片数据
*/
- public byte[] getImageFromURL(String urlPath){
- byte[] data=null;
- InputStream is=null;
- HttpURLConnection conn=null;
- try {
- URL url=new URL(urlPath);
- conn=(HttpURLConnection) url.openConnection();
- conn.setDoInput(true);
- //conn.setDoOutput(true);
- conn.setRequestMethod("GET" );
- conn.setConnectTimeout(6000 );
- is=conn.getInputStream();
- if(conn.getResponseCode()==200 ){
- data=readInputStream(is);
- }
- else System.out.println("发生异常!" );
- } catch (MalformedURLException e) {
- e.printStackTrace();
- } catch (IOException e) {
- e.printStackTrace();
- }
- finally{
- conn.disconnect();
- try {
- is.close();
- } catch (IOException e) {
- e.printStackTrace();
- }
- }
- return data;
- }
- /**
- * 读取InputStream数据,转为byte[]数据类型
- * @param is InputStream数据
- * @return 返回byte[]数据
- */
- public byte[] readInputStream(InputStream is) {
- ByteArrayOutputStream baos=new ByteArrayOutputStream();
- byte[] buffer=new byte[1024 ];
- int length=-1 ;
- try {
- while((length=is.read(buffer))!=-1 ){
- baos.write(buffer, 0 , length);
- }
- baos.flush();
- } catch (IOException e) {
- e.printStackTrace();
- }
- byte[] data=baos.toByteArray();
- try {
- is.close();
- baos.close();
- } catch (IOException e) {
- e.printStackTrace();
- }
- return data;
- }
- /**
- * 根据网络图片地址集批量获取网络图片
- * @param urlPath 网络图片地址数组
- * @return 返回Bitmap数据类型的数组
- */
- public Bitmap[] getBitmapArray(String[] urlPath){
- int length=urlPath.length;
- if(urlPath==null||length<1 ){
- return null;
- }
- else{
- Bitmap[] bitmaps=new Bitmap[length];
- for (int i = 0 ; i < length; i++) {
- byte[] imageByte=getImageFromURL(urlPath[i].trim());
- //以下是把图片转化为缩略图再加载
- BitmapFactory.Options options = new BitmapFactory.Options();
- options.inJustDecodeBounds = true;
- Bitmap bitmap=BitmapFactory.decodeByteArray(imageByte, 0 , imageByte.length, options);
- options.inJustDecodeBounds = false;
- int be = (int)(options.outHeight / (float)200 );
- if (be <= 0 ) be = 1 ;
- options.inSampleSize = be;
- bitmaps[i]=BitmapFactory.decodeByteArray(imageByte, 0 , imageByte.length,options);
- }
- return bitmaps;
- }
- }
以