图片压缩

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package com.example.imageresizer;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.AsyncTask;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.view.View;import android.widget.ImageView;import com.example.imageresizer.utils.ImageResizer;import java.io.InputStream;import java.net.HttpURLConnection;import java.net.URL;public class MainActivity extends AppCompatActivity {    private ImageView ivIcon;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        //找控件        ivIcon = (ImageView) findViewById(R.id.ivIcon);    }    public void btnResizerImage(View view){        loadImage("http://i3.s2.dpfile.com/2010-12-20/6201691_b.jpg(249x249)/thumb.jpg");    }    private void loadImage(String path){        new AsyncTask<String,Void,Bitmap>(){            @Override            protected void onPostExecute(Bitmap bitmap) {                super.onPostExecute(bitmap);                if(bitmap != null)                    ivIcon.setImageBitmap(bitmap);                else                    ivIcon.setImageResource(R.mipmap.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)                        *//*int inSampleSize = ImageResizer.caculateSampleSize(options,50,50);                        System.out.println("采样率 : "+inSampleSize);*//*                        options.inSampleSize = ImageResizer.caculateSampleSize(options,50,50);                        options.inJustDecodeBounds = false;                        //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);                        //Bitmap bitmap = ImageResizer.decodeStreamFromNetWork(url,is,50,50);                        return ImageResizer.decodeStreamFromNetWork(url,is,50,50);                    }                } catch (Exception e) {                    e.printStackTrace();                }                return null;            }        }.execute(path);    }}

package com.example.imageresizer.utils;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import java.io.InputStream;import java.net.URL;public class ImageResizer {    /**     *  计算图片的采样率     * @param options     * @param reqWidth  你所期望压缩的宽度     * @param reqHeight  你所期望压缩的高度     */    public static int caculateSampleSize(BitmapFactory.Options options,int reqWidth,int reqHeight){        //得到这个图片的原始宽高        int width = options.outWidth;        int height = options.outHeight;        System.out.println("宽:"+width+"高 : "+height);        int inSampleSize = 1;        if(width > reqWidth || height > reqHeight){            int halfWidth = width / 2;            int halfHeight = height / 2;            while ((halfWidth / inSampleSize) >= reqWidth && (halfHeight / inSampleSize) >= reqHeight){                inSampleSize *= 2;            }        }        return inSampleSize;    }    /**     * 图片压缩彻底封装     * @param url     * @param is     * @param reqWidth     * @param reqHeight     * @return     * @throws Exception     */    public static Bitmap decodeStreamFromNetWork(URL url, InputStream is, int reqWidth, int reqHeight) throws Exception{        BitmapFactory.Options options = new BitmapFactory.Options();        //假解析        options.inJustDecodeBounds = true;        BitmapFactory.decodeStream(is,null,options);        //计算采样率        options.inSampleSize = caculateSampleSize(options,reqWidth,reqHeight);        //开始真正解析图片        options.inJustDecodeBounds = false;        //关闭流,避免decodeStream(1,2,3);bug        is.close();        InputStream inputStream = url.openStream();        return BitmapFactory.decodeStream(inputStream,null,options);    }}

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