网络图片采样

package com.bwie.secondsamplelibrary;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.AsyncTask;import android.widget.ImageView;import java.io.InputStream;import java.net.HttpURLConnection;import java.net.URL;/** * 类的用途 * * @author  * @date 2017/9/21 21:09 */public class TwoImageUtils {    public static void loadImage(String path, final ImageView imageView) {        new AsyncTask<String, Void, Bitmap>() {            @Override            protected void onPostExecute(Bitmap bitmap) {                super.onPostExecute(bitmap);                if (bitmap != null)                    imageView.setImageBitmap(bitmap);                else                    imageView.setImageResource(R.drawable.ic_launcher);            }            @Override            protected Bitmap doInBackground(String... params) {                try {                    String path = params[0];                    URL url = new URL(path);                    HttpURLConnection connection = (HttpURLConnection) url.openConnection();                    connection.setRequestMethod("GET");                    connection.setConnectTimeout(5000);                    connection.setReadTimeout(5000);                    int code = connection.getResponseCode();                    if (code == 200) {                        //得到图片数据                        InputStream is = connection.getInputStream();                        //BitmapFactory.decodeStream(is);//ARGB_888 一个像素占 4个字节  ARGB_565 一个像素占 2 个字节  Alpha Red、Green、Blue(颜色)                        BitmapFactory.Options options = new BitmapFactory.Options();                        //在图片真正解析之前，不要解析图片数据，只需要告诉一下转换器，只要获取图片的像素(宽高)                        options.inJustDecodeBounds = true;//告诉BitmapFactory转换工厂不去真正解析图片只需要拿到图片宽高就行                        //假解析 API 有bug                        BitmapFactory.decodeStream(is, null, options);                        //压缩，根据图片采样率进行二次采样   100 * 100 是你所期望的具体图片尺寸                        //options.inSampleSize = 2; //采样用来计算图片的宽高(1920 * 1080 -> 1920 / 2 1080 / 2)                        //获取图片宽高，注意：图片的原始宽高                        int width = options.outWidth;                        int height = options.outHeight;                        System.out.println("宽:" + width + "高 ： " + height);                        //定义一个变量去记住我们采样率                        int inSampleSize = 1;//默认是1 ,即不对图片进行任何压缩                        if (width > 100 || height > 100) {                            int halfWidth = width / 2;                            int halfHeight = height / 2;                            while ((halfWidth / inSampleSize) >= 100 && (halfHeight / inSampleSize) >= 100) {                                //计算采样率                                inSampleSize *= 2;                            }                        }                        //采样率改变了                        options.inSampleSize = inSampleSize;// 8                        //图片压缩完之后，放行图片解析                        options.inJustDecodeBounds = false;//告诉图片转换工厂，可以解析图片了                        //关闭之前的流                        is.close();                        //重新再去得到当前这张图片的字节流数据                        is = url.openStream();                        //开始解析图片                        Bitmap bitmap = BitmapFactory.decodeStream(is, null, options);                        //关闭流                        is.close();                        // Bitmap bitmap = BitmapFactory.decodeStream(is);                        return bitmap;                    }                } catch (Exception e) {                    e.printStackTrace();                }                return null;            }        }.execute(path);    }}