我正在开发一款具有背景图片的应用。因为这个图像非常大，所以我使用了一些代码来确保它足够小，不会让应用程序耗尽内存。但是在将位图设置为ImageView之后，应用程序会冻结并开始跳过帧。当我按下按钮时，没有任何反应，没有动画，也没有执行任何方法。这是我的代码：
package com.github.legosteen11.testing;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.DisplayMetrics;
import android.view.Display;
import android.widget.ImageView;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ImageView mImg;
mImg = (ImageView) findViewById(R.id.backgroundImage);
Display display = getWindowManager().getDefaultDisplay();
DisplayMetrics displaymetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
int height = displaymetrics.heightPixels;
int width = displaymetrics.widthPixels;
mImg.setImageBitmap(decodeSampledBitmapFromResource(getResources(), R.drawable.background_1, width, height));
}
public static Bitmap decodeSampledBitmapFromResource(Resources res, int resId,
int reqWidth, int reqHeight) {
// First decode with inJustDecodeBounds=true to check dimensions
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(res, resId, options);
// Calculate inSampleSize
options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
// Decode bitmap with inSampleSize set
options.inJustDecodeBounds = false;
return BitmapFactory.decodeResource(res, resId, options);
}
public static int calculateInSampleSize(
BitmapFactory.Options options, int reqWidth, int reqHeight) {
// Raw height and width of image
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
// Calculate ratios of height and width to requested height and width
final int heightRatio = Math.round((float) height / (float) reqHeight);
final int widthRatio = Math.round((float) width / (float) reqWidth);
// Choose the smallest ratio as inSampleSize value, this will guarantee
// a final image with both dimensions larger than or equal to the
// requested height and width.
inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
}
return inSampleSize;
}
}
这是我的XML：
<RelativeLayout 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"
tools:context="com.github.legosteen11.testing.MainActivity">
<ImageView
android:id="@+id/backgroundImage"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="centerCrop"
android:src="@drawable/ic_launcher" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:layout_margin="16dp">
<TextView
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="5"
android:textSize="45sp"
android:textAlignment="center"
android:text="Welcome!"/>
<TextView
android:layout_weight="0"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAlignment="center"
android:textSize="24sp"
android:text="How long will you be away?"/>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="0"
android:layout_marginBottom="16dp">
<TextView
android:id="@+id/amountDays"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:textSize="56sp"
android:text="0" />
<TextView
android:id="@+id/daysTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@id/amountDays"
android:text="days"
android:layout_toRightOf="@id/amountDays"
android:textSize="24sp" />
</RelativeLayout>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<Button
android:id="@+id/continueDaysButton"
android:text="Continue"
android:layout_centerHorizontal="true"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="helloWorld"/>
</RelativeLayout>
</LinearLayout>
</RelativeLayout>
编辑： logcat，没有错误，但感谢这里的评论：）
05-04 14:58:32.354 18034-18034/com.github.legosteen11.testing W/System: ClassLoader referenced unknown path: /data/app/com.github.legosteen11.testing-2/lib/arm64
05-04 14:58:32.401 18034-18046/com.github.legosteen11.testing W/art: Suspending all threads took: 22.270ms
05-04 14:58:32.403 18034-18046/com.github.legosteen11.testing I/art: Background sticky concurrent mark sweep GC freed 1969(115KB) AllocSpace objects, 0(0B) LOS objects, 0% free, 19MB/19MB, paused 23.077ms total 41.996ms
05-04 14:58:32.643 18034-18034/com.github.legosteen11.testing W/System: ClassLoader referenced unknown path: /data/app/com.github.legosteen11.testing-2/lib/arm64
05-04 14:58:32.758 18034-18034/com.github.legosteen11.testing W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
05-04 14:58:33.695 18034-18095/com.github.legosteen11.testing D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: true
05-04 14:58:33.748 18034-18095/com.github.legosteen11.testing I/Adreno: QUALCOMM build : 63c06b2, I8366cd0437
Build Date : 12/06/15
OpenGL ES Shader Compiler Version: XE031.05.13.02
Local Branch : mybranch17112971
Remote Branch : quic/LA.BF64.1.2.9_v2
Remote Branch : NONE
Reconstruct Branch : NOTHING
05-04 14:58:33.753 18034-18095/com.github.legosteen11.testing I/OpenGLRenderer: Initialized EGL, version 1.4
05-04 14:58:35.205 18034-18034/com.github.legosteen11.testing I/Choreographer: Skipped 84 frames! The application may be doing too much work on its main thread.
05-04 14:58:36.561 18034-18034/com.github.legosteen11.testing I/Choreographer: Skipped 80 frames! The application may be doing too much work on its main thread.
05-04 14:58:37.956 18034-18034/com.github.legosteen11.testing I/Choreographer: Skipped 83 frames! The application may be doing too much work on its main thread.
答案 0 :(得分：0)
只需在不同的线程上执行代码即可 它会加载到不同的线程上，这样你的ui就不会有任何负载 在onCreate之外将其声明为全局
ImageView mImg;
public class DownloadFromServer extends AsyncTask<String, Void, Bitmap> {
Context mContext;
public DownloadFromServer(Context context) {
mContext = context;
}
@Override
protected void onPostExecute(Bitmap s) {
super.onPostExecute(s);
mImg.setBitmap(s);
}
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected ScData doInBackground(String... params) {
Bitmap bmp=decodeSampledBitmapFromResource(getResources(), R.drawable.background_1, width, height);
return bmp;
}
}