OOM的全称是out of memory exception.当使用setImageBitmap()显示图片时有时会引起该异常。那么是什么原因呢?我们知道一张图片是有很多个像素点组成的,bmp格式图片一个像素需要3字节(RGB,每个颜色一个字节表示)或者4字节(RGBA)表示。如果一张图片分辨率为4266*2900 ,那么它有 12371400 像素点,使用setImageBitmap()所需内存为:12371400 *4byte=49485616字节约48M,当前模拟器设置的VM heap是32M,所以会报OOM异常。
该如何解决呢?假设模拟器的分辨率我320*480。在分辨率有限的情况下,可以采取缩放图片的方法。4266/320 =13 2900/480 =6 选取较大的那个缩放比例来设置。
源代码如下:
1 package com.example.day17_01pictureloader; 2 3 import android.app.Activity; 4 import android.graphics.Bitmap; 5 import android.graphics.BitmapFactory; 6 import android.graphics.BitmapFactory.Options; 7 import android.os.Bundle; 8 import android.os.Debug; 9 import android.os.Environment; 10 import android.view.Display; 11 import android.view.Menu; 12 import android.view.MenuItem; 13 import android.view.View; 14 import android.widget.ImageView; 15 16 public class MainActivity extends Activity { 17 18 @Override 19 protected void onCreate(Bundle savedInstanceState) { 20 super.onCreate(savedInstanceState); 21 setContentView(R.layout.activity_main); 22 } 23 24 public void loadpicture(View v){ 25 ImageView iv_iamge = (ImageView) findViewById(R.id.iv_image); 26 //iv_iamge.setImageResource(R.drawable.fun1); 27 String path = Environment.getExternalStorageDirectory().getAbsolutePath() 28 +"/DCIM/100ANDRO/cameras/dd.jpg"; 29 Bitmap bm = BitmapFactory.decodeFile(path); 30 iv_iamge.setImageBitmap(bm); 31 } 32 33 public void scaleloadpicture(View v){ 34 String path = Environment.getExternalStorageDirectory().getAbsolutePath() 35 +"/DCIM/100ANDRO/cameras/pp.jpeg"; 36 //decode需要添加一些option 37 Options opt =new Options(); 38 opt.inJustDecodeBounds = true; 39 Bitmap bm = BitmapFactory.decodeFile(path,opt); 40 int original_width = opt.outWidth; 41 int original_heigth= opt.outHeight ; 42 System.out.println("图片的原始宽高"+original_width+","+original_heigth); 43 44 //获取屏幕的宽高 45 Display display = getWindowManager().getDefaultDisplay(); 46 int screenWidth = display.getWidth(); 47 int screenHeight = display.getHeight(); 48 System.out.println("屏幕的宽和高: " + screenWidth + " * " + screenHeight); 49 50 //计算缩放比例 51 int scale_width = original_width/screenWidth ; 52 int scale_height = original_heigth/screenHeight ; 53 int scale = scale_width>scale_height? scale_width:scale_height; 54 System.out.println("缩放的比例: " + scale ); 55 56 //重新设置decode的参数,加上缩放比例的参数 57 opt.inJustDecodeBounds = false; 58 // opt.inScaled = scale; 59 opt.inSampleSize =scale; 60 bm = BitmapFactory.decodeFile(path,opt); 61 62 //将缩放后的图片加载到imageview上 63 ImageView iv_iamge = (ImageView) findViewById(R.id.iv_image); 64 iv_iamge.setImageBitmap(bm); 65 } 66 }
1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 2 xmlns:tools="http://schemas.android.com/tools" 3 android:layout_width="match_parent" 4 android:layout_height="match_parent" 5 android:paddingBottom="@dimen/activity_vertical_margin" 6 android:paddingLeft="@dimen/activity_horizontal_margin" 7 android:paddingRight="@dimen/activity_horizontal_margin" 8 android:paddingTop="@dimen/activity_vertical_margin" 9 tools:context="com.example.day17_01pictureloader.MainActivity" 10 android:orientation="vertical"> 11 12 <TextView 13 android:layout_width="wrap_content" 14 android:layout_height="wrap_content" 15 android:text="@string/hello_world" /> 16 <Button 17 android:layout_width="wrap_content" 18 android:layout_height="wrap_content" 19 android:text="加载图片" 20 android:onClick="loadpicture"/> 21 <Button 22 android:layout_width="wrap_content" 23 android:layout_height="wrap_content" 24 android:text="缩放加载图片" 25 android:onClick="scaleloadpicture"/> 26 <ImageView 27 android:id="@+id/iv_image" 28 android:layout_width="wrap_content" 29 android:layout_height="wrap_content" 30 /> 31 </LinearLayout>
时间: 2024-10-02 21:06:29