不能将图像从SD卡加载到网格视图

Question

您好，我想加载从相机捕获到网格视图的所有图像。但我得到这个奇怪的例外。如果我只是尝试加载2或3张图片，一切都很顺利，但是当我尝试加载所有时出现错误。我的sdcard中有大约20张图片。这是我的代码。

package com.example.imagegridview; 

import java.io.File; 
import java.util.ArrayList; 

import android.annotation.SuppressLint; 
import android.app.Activity; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.os.Bundle; 
import android.os.Environment; 
import android.util.Log; 
import android.view.Menu; 
import android.widget.GridView; 
import android.widget.Toast; 

@SuppressLint("NewApi") 
public class MainActivity extends Activity { 

    ArrayList<Bitmap> data; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     String sdCardRootPath = Environment.getExternalStoragePublicDirectory(
       Environment.DIRECTORY_DCIM).toString()+"/Camera"; 
     File rootFolder = new File(sdCardRootPath); 
     File[] picFiles = rootFolder.listFiles(); 
     data = new ArrayList<Bitmap>(); 
     for (File pic:picFiles) { 
      Bitmap b= BitmapFactory.decodeFile(pic.getAbsolutePath()); 
      data.add(b); 
     } 
     GridView gv = (GridView) findViewById(R.id.gridview); 
     gv.setAdapter(new MAdapter(this,data)); 

    } 

} 

适配器

package com.example.imagegridview; 

import java.util.ArrayList; 

import android.content.Context; 
import android.graphics.Bitmap; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.BaseAdapter; 
import android.widget.ImageView; 

public class MAdapter extends BaseAdapter { 

    Context c; 
    ArrayList<Bitmap> b; 
    public MAdapter(Context c,ArrayList<Bitmap> data){ 
     this.c = c; 
     this.b = data; 
    } 
    @Override 
    public int getCount() { 
     // TODO Auto-generated method stub 
     return b.size(); 
    } 

    @Override 
    public Object getItem(int arg0) { 
     // TODO Auto-generated method stub 
     return b.get(arg0); 
    } 

    @Override 
    public long getItemId(int arg0) { 
     // TODO Auto-generated method stub 
     return 0; 
    } 

    @Override 
    public View getView(int arg0, View arg1, ViewGroup arg2) { 
     ImageView iv = new ImageView(c); 
     iv.setImageBitmap(b.get(arg0)); 
     return iv; 
    } 

} 

layout.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:orientation="vertical"> 
<GridView 
    android:id="@+id/gridview" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:columnWidth="90dp" 
    android:numColumns="auto_fit" 
    android:verticalSpacing="10dp" 
    android:horizontalSpacing="10dp" 
    android:stretchMode="columnWidth" 
    android:gravity="center"/> 

</LinearLayout> 

logcat的

03-13 23:39:22.632: E/AndroidRuntime(13228): java.lang.OutOfMemoryError: bitmap size exceeds VM budget 
03-13 23:39:22.632: E/AndroidRuntime(13228): at android.graphics.BitmapFactory.nativeDecodeStream(Native Method) 
03-13 23:39:22.632: E/AndroidRuntime(13228): at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:562) 
03-13 23:39:22.632: E/AndroidRuntime(13228): at android.graphics.BitmapFactory.decodeFile(BitmapFactory.java:371) 
03-13 23:39:22.632: E/AndroidRuntime(13228): at android.graphics.BitmapFactory.decodeFile(BitmapFactory.java:399) 
03-13 23:39:22.632: E/AndroidRuntime(13228): at com.example.imagegridview.MainActivity.onCreate(MainActivity.java:32) 
03-13 23:39:22.632: E/AndroidRuntime(13228): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
03-13 23:39:22.632: E/AndroidRuntime(13228): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2633) 
03-13 23:39:22.632: E/AndroidRuntime(13228): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2685) 
03-13 23:39:22.632: E/AndroidRuntime(13228): at android.app.ActivityThread.access$2300(ActivityThread.java:126) 
03-13 23:39:22.632: E/AndroidRuntime(13228): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2038) 
03-13 23:39:22.632: E/AndroidRuntime(13228): at android.os.Handler.dispatchMessage(Handler.java:99) 
03-13 23:39:22.632: E/AndroidRuntime(13228): at android.os.Looper.loop(Looper.java:123) 
03-13 23:39:22.632: E/AndroidRuntime(13228): at android.app.ActivityThread.main(ActivityThread.java:4633) 
03-13 23:39:22.632: E/AndroidRuntime(13228): at java.lang.reflect.Method.invokeNative(Native Method) 
03-13 23:39:22.632: E/AndroidRuntime(13228): at java.lang.reflect.Method.invoke(Method.java:521) 
03-13 23:39:22.632: E/AndroidRuntime(13228): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:858) 
03-13 23:39:22.632: E/AndroidRuntime(13228): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
03-13 23:39:22.632: E/AndroidRuntime(13228): at dalvik.system.NativeStart.main(Native Method) 

Answer 1

你可能想通过这个文档

https://developer.android.com/training/displaying-bitmaps/index.html

Answer 2

我建议你在直接添加图像之前，u缩放每个图像。 来自相机的图像实际上会具有相当大的尺寸，当您尝试添加20个这样的图像时，它的界限会在移动设备上溢出。 因此，在上传它之前缩放每个图像，并确定它会起作用。

Answer 3

加载前调整位图大小，即使用下面的代码解码位图，然后使用该位图。 `

 public Bitmap decodeFile(File f, int size) { 

      try { 
     // decode image size 
     BitmapFactory.Options o = new BitmapFactory.Options(); 
     o.inJustDecodeBounds = true; 
     BitmapFactory.decodeStream(new FileInputStream(f), null, o); 

     // Find the correct scale value. It should be the power of 2. 
     final int REQUIRED_SIZE = size; 
     int width_tmp = o.outWidth, height_tmp = o.outHeight; 
     int scale = 1; 
     while (true) { 
      if (width_tmp/2 < REQUIRED_SIZE 
        || height_tmp/2 < REQUIRED_SIZE) 
       break; 
      width_tmp /= 2; 
      height_tmp /= 2; 
      scale *= 2; 
     } 

     // decode with inSampleSize 
     BitmapFactory.Options o2 = new BitmapFactory.Options(); 
     o2.inSampleSize = scale; 
     o2.outWidth = width_tmp; 
     o2.outHeight = height_tmp; 
     return BitmapFactory.decodeStream(new FileInputStream(f), null, o2); 
    } catch (FileNotFoundException e) { 
    } 
    return null; 
}`