android 图片内存溢出解决方案.docx

java.lang.OutOfMemoryError: bitmap size exceeds VM budget解决方法用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：?123BitmapFactory.Options opts = newBitmapFactory.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。?123BitmapFactory.Options opts = newBitmapFactory.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。?12345678910111213141516171819202122232425262728293031323334353637383940414243publicstaticintcomputeSampleSize(BitmapFactory.Options options,intminSideLength, intmaxNumOfPixels) intinitialSize = computeInitialSampleSize(options, minSideLength,maxNumOfPixels);introundedSize;if(initialSize = 8) roundedSize = 1;while(roundedSize initialSize) roundedSize = 1; elseroundedSize = (initialSize + 7) / 8* 8;returnroundedSize;privatestaticintcomputeInitialSampleSize(BitmapFactory.Options options,intminSideLength, intmaxNumOfPixels) doublew = options.outWidth;doubleh = options.outHeight;intlowerBound = (maxNumOfPixels = -1) ? 1:(int) Math.ceil(Math.sqrt(w * h / maxNumOfPixels);intupperBound = (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.returnlowerBound;if(maxNumOfPixels = -1) &(minSideLength = -1) return1; elseif(minSideLength = -1) returnlowerBound; elsereturnupperBound; 使用该算法，就可动态计算出图片的inSampleSize。?1234567891011BitmapFactory.Options opts = newBitmapFactory.Options();opts.inJustDecodeBounds = true;BitmapFactory.decodeFile(imageFile, opts);opts.inSampleSize = computeSampleSize(opts, -1, 128*128); opts.inJustDecodeBounds = false;tryBitmap 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(urlPathi.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trueBitmap 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 be = (int)(options.outHeight / (float)200); if (be = 0) be = 1; options.inSampleSize = be; /计算得到图片缩小倍数bitmapsi=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*paramurlPath图片网络地址*return图片数据 */ 1. publicbytegetImageFromURL(StringurlPath)2. bytedata=null;3. InputStreamis=null;4. HttpURLConnectionconn=null;5. try6. URLurl=newURL(urlPath);7. conn=(HttpURLConnection)url.openConnection();8. conn.setDoInput(true);9. /conn.setDoOutput(true);10. conn.setRequestMethod(GET);11. conn.setConnectTimeout(6000);12. is=conn.getInputStream();13. if(conn.getResponseCode()=200)14. data=readInputStream(is);15. 16. elseSystem.out.println(发生异常！);17. 18. catch(MalformedURLExceptione)19. e.printStackTrace();20. catch(IOExceptione)21. e.printStackTrace();22. 23. finally24. conn.disconnect();25. try26. is.close();27. catch(IOExceptione)28. e.printStackTrace();29. 30. 31. returndata;32. 33. 34. /*35. *读取InputStream数据，转为byte数据类型36. *paramisInputStream数据37. *return返回byte数据38. */39. publicbytereadInputStream(InputStreamis)40. ByteArrayOutputStreambaos=newByteArrayOutputStream();41. bytebuffer=newbyte1024;42. intlength=-1;43. try44. while(length=is.read(buffer)!=-1)45. baos.write(buffer,0,length);46. 47. baos.flush();48. catch(IOExceptione)49. e.printStackTrace();50. 51. bytedata=baos.toByteArray();52. try53. is.close();54. baos.close();55. catch(IOExceptione)56. e.printStackTrace();57. 58. returndata;59. 60. 61. /*62. *根据网络图片地址集批量获取网络图片63. *paramurlPath网络图片地址数组64. *return返回Bitmap数据类型的数组65. */66. publicBitmapgetBitmapArray(StringurlPath)67. intlength=urlPath.length;68. if(urlPath=null|length1)69. returnnull;70. 71. else72. Bitmapbitmaps=newBitmaplength;73. for(inti=0;ilength;i+)74. byteimageByte=getImageFromURL(urlPathi.trim();75. 76. /以下是把图片转化为缩略图再加载77. BitmapFactory.Optionsoptions=newBitmapFactory.Options();78. options.inJustDecodeBounds=true;79. Bitmapbitmap=BitmapFactory.decodeByteArray(imageByte,0,imageByte.length,options);8