Android一分鐘瞭解圖片OOM

Android 圖片加載經常出現內存OOM異常，處理起來也很複雜，主要是圖片分辨率過大（如：2880*1620），但是基本原理大概如下：

public static Bitmap oomSolution(Resources res,int resID,int widthpx,int heightpx){
		Options options =new BitmapFactory.Options();
		options.inJustDecodeBounds=true;//不在內存中讀取圖片
		options.inPreferredConfig = Bitmap.Config.RGB_565;//代表RGB位圖
		BitmapFactory.decodeResource(res,resID, options);//壓縮前圖片
		int width= options.outWidth;//原始圖片寬
		int height=options.outHeight;//原始圖片高
		if(height>heightpx||width>widthpx){
			int inheight=Math.round((float)height/(float)heightpx);
			int inwidth=Math.round((float)width/(float)widthpx);
			int inSize=inheight>inwidth?inheight:inwidth;
			options.inSampleSize=inSize;//縮放值:1不縮放 2爲縮放1/2
		}
		options.inJustDecodeBounds=false;//在內存中創建圖片
		Bitmap bm = BitmapFactory.decodeResource(res,resID, options);//壓縮後的圖片
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		bm.compress(Bitmap.CompressFormat.JPEG,20, baos);//壓縮圖片
		return bm;
	}

來源：http://blog.csdn.net/a704755096/article/details/49912211

 

附：Bitmap圖片轉換工具

import java.io.ByteArrayOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import android.app.Activity;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.BitmapFactory.Options;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Matrix;
import android.graphics.Shader;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.view.View;
import android.widget.ImageView;

public class BitmapUtils {
	/**
	 *Bitmap to Drawable
	 * @param bmp
	 * @return Drawable
	 */
	public static Drawable getBitmapDrawable(Bitmap bmp) {
		BitmapDrawable bd = new BitmapDrawable(bmp);
		return bd;
	}
	/**
	 * Drawable to Bitmap
	 * @param drawable
	 * @return Bitmap
	 */
	public static Bitmap getDrawableBitmap(Drawable drawable) {
		BitmapDrawable bd = (BitmapDrawable) drawable;
		Bitmap bm = bd.getBitmap();
		return bm;
	}
	/**資源圖片Resources to Bitmap
	 * @param activity
	 * @param resId
	 * @return Bitmap
	 */
	public static Bitmap getResourcesBitmap(Activity activity, int resId) {
		Resources res = activity.getResources();
		return BitmapFactory.decodeResource(res, resId);
	}
	/**數組轉圖片byte[] to Bitmap
	 * @param bytee
	 * @return Bitmap
	 */
	public static Bitmap getBytesBimap(byte[] bytee) {
		if (bytee.length == 0) {
			return null;
		}
		return BitmapFactory.decodeByteArray(bytee, 0,bytee.length);
	}
	/**圖片轉數組Bitmap to byte[]
	 * @param bm
	 * @return byte[]
	 */
	public static byte[] getBitmapBytes(Bitmap bm) {
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		bm.compress(Bitmap.CompressFormat.JPEG,20, baos);
		return baos.toByteArray();
	}
	/**放大圖片
	 * @param bitmap
	 * @return Bitmap
	 */
	public static Bitmap getBigBitmap(Bitmap bitmap) {
		Matrix matrix = new Matrix();
		matrix.postScale(1.5f,1.5f); //長和寬放大縮小的比例
		Bitmap resizeBmp = Bitmap.createBitmap(bitmap,0,0,bitmap.getWidth(),bitmap.getHeight(),matrix,true);
		return resizeBmp;
	}
	/**縮小圖片
	 * @param bitmap
	 * @return Bitmap
	 */
	public static Bitmap getSmallBitmap(Bitmap bitmap) {
		Matrix matrix = new Matrix();
		matrix.postScale(0.4f ,0.4f); //長和寬放大縮小的比例
		Bitmap resizeBmp = Bitmap.createBitmap(bitmap,0,0,bitmap.getWidth(),bitmap.getHeight(),matrix,true);
		return resizeBmp;
	}
    /**圓形圖片
     * @param source
     * @return Bitmap
     */
    public static Bitmap getCircleImage(Bitmap source) {
        int length = source.getWidth() < source.getHeight() ? source.getWidth() : source.getHeight();
        Paint paint = new Paint();
        paint.setAntiAlias(true);
        paint.setShader(new BitmapShader(source,Shader.TileMode.CLAMP,Shader.TileMode.CLAMP));//遮罩
        Bitmap bmp = Bitmap.createBitmap(length,length,source.getConfig());
        Canvas canvas = new Canvas(bmp);
        canvas.drawCircle(length / 2, length / 2, length / 2, paint);
        return bmp;
    }
	/**線程獲取url圖片url to Bitmap
	 * @param img imageview
	 * @param urlstr url地址
	 * @param isCircular true圓形,false不變
	 */
	public static void getUrlBitmap(final ImageView img,final String urlstr,final boolean isCircular){
		if(urlstr==null||urlstr.trim().length()==0){
			return;
		}
		new Thread(){
			@Override
			public void run() {
				super.run();
				try {
					URL url = new URL(urlstr);
					URLConnection conn = url.openConnection();
					conn.connect();
					InputStream in = conn.getInputStream();
					final Bitmap map = BitmapFactory.decodeStream(in);
					in.close();
					img.post(new Runnable() {
						@Override
						public void run() {
							if(isCircular) {
								img.setImageBitmap(getCircleImage(map));
							}else{
								img.setImageBitmap(map);
							}
						}
					});
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}.start();
	}
    /**截屏Screenshot(view轉Bitmap)加背景框http://blog.csdn.net/yanzi1225627/article/details/8622257
     * @param view 當前視圖截屏getWindow().getDecorView()
     * @return Bitmap
     */
    public static Bitmap getScreenshotBitmap(View view){
        //當前視圖截屏view=getWindow().getDecorView()
        int viewWidth = view.getMeasuredWidth();
        int viewHeight = view.getMeasuredHeight();
        Bitmap bitmap=null;
        if (viewWidth > 0 && viewHeight > 0) {
            bitmap = Bitmap.createBitmap(viewWidth, viewHeight, Config.RGB_565);
            Canvas cvs = new Canvas(bitmap);
            //cvs.drawColor(view.getDrawingCacheBackgroundColor());
            view.draw(cvs);
//		MediaStore.Images.Media.insertImage(getContentResolver(),bitmap,"title","description");//保存下載到相冊-返回uriString
//		sendBroadcast(new Intent( Intent.ACTION_MEDIA_SCANNER_SCAN_FILE,Uri.fromFile(new File(getPath(uriString)))));//刷新相冊-getPath函數uriString轉路徑(禁用)
            return bitmap;
        }
//      MediaMetadataRetriever retriever = new MediaMetadataRetriever();//本地視頻截圖
//      retriever.setDataSource(filePath);
//      String timeString = retriever.extractMetadata(MediaMetadataRetriever.METADATA_KEY_DURATION);
//      retriever.getFrameAtTime(Long.parseLong(timeString) * 1000);
        return bitmap;
    }
	/**文件圖片解決OOM(file to Bitmap)
	 * @param filepath SD卡本地路徑注意版本兼容
	 * @return Bitmap
	 */
	public static Bitmap getOOMBitmap(String filepath){
		Options options =new BitmapFactory.Options();
		options.inJustDecodeBounds=true;//不在內存中讀取圖片
		options.inPreferredConfig = Bitmap.Config.RGB_565;//代表RGB位圖
		options.inSampleSize=2;//縮放值:1不縮放 2爲縮放1/2
		BitmapFactory.decodeFile(filepath, options);//壓縮前圖片

		options.inJustDecodeBounds=false;//在內存中創建圖片
		Bitmap bm = BitmapFactory.decodeFile(filepath, options);//壓縮後的圖片
		try {
			FileOutputStream fos = new FileOutputStream(filepath);
			bm.compress(Bitmap.CompressFormat.JPEG, 15, fos);//壓縮圖片
			fos.close();
		}catch (IOException e){
//			e.printStackTrace();
		}
		return bm;
	}

}