android中加载大图片到内存

在android中，要明确一点，图片占用的内存大小与图片的实际大小无关，只与图片的分辨率有关，图片占用的内存空间为图片分辨率（高*宽）*4byte。

布局文件

<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"              tools:context=".MainActivity">    <Button        android:id="@+id/bt"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="加载大图片"/>    <ImageView        android:id="@+id/iv"        android:layout_width="match_parent"        android:layout_height="match_parent"/></LinearLayout>

实现代码

package cn.test.ning.imagedemo;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.Bundle;import android.view.View;import android.view.WindowManager;import android.widget.Button;import android.widget.ImageView;public class MainActivity extends Activity {    private ImageView iv;    private Button bt;    private int screenWidth;    private int screenHight;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_bigimage);        //获取屏幕信息        WindowManager windowManager = (WindowManager) getSystemService(WINDOW_SERVICE);        //获取屏幕宽度        screenWidth = windowManager.getDefaultDisplay().getWidth();        //获取屏幕高度        screenHight = windowManager.getDefaultDisplay().getHeight();        iv = (ImageView) this.findViewById(R.id.iv);        // Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher);        // iv.setImageBitmap(bitmap);        bt = (Button) this.findViewById(R.id.bt);        bt.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {               // Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.very_large_photo);                BitmapFactory.Options opts = new BitmapFactory.Options();                //不真实的解析位图，只是返回位图的相关信息                opts.inJustDecodeBounds = true;                Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.very_large_photo,opts);                int width = opts.outWidth;//图片的宽度                int higth = opts.outHeight;//图片的高度                //计算缩放比                int scale = 1;                int scaleX = width /screenWidth;                int scaleY = higth /screenHight;                scale = (scaleX>scaleY?scaleX:scaleY);                if (scale<1){                    scale = 1;                }                //设置图片的缩放比                opts.inSampleSize = scale;                //真实解析位图                opts.inJustDecodeBounds = false;                //加载图片 重要的步骤                bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.very_large_photo,opts);                iv.setImageBitmap(bitmap);            }        });    }}

使用到的图片

android中加载大图片到内存_第1张图片

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