压缩图片

  public class MainActivity extends AppCompatActivity {

      private ImageView img;

      @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //找到控件
          img = (ImageView) findViewById(R.id.img);
    }


    public void btnLoadImage(View view){


        getLoadiImg("http://tnfs.tngou.net/image/info/150912/6f1f81106d337d769882e34f481cc191.jpg");

    }


    private void getLoadiImg(String url){

        new AsyncTask(){

            @Override
            protected void onPostExecute(Bitmap bitmap) {
                super.onPostExecute(bitmap);

                if (bitmap != null){
                    img.setImageBitmap(bitmap);
                }else {
                    img.setImageResource(R.mipmap.ic_launcher_round);
                }
            }

            @Override
            protected Bitmap doInBackground(String... strings) {

                try {
                    //得到请求地址
                    String path = strings[0];
                    URL url = new URL(path);
                    //打开链接
                    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                    //设置请求方式get
                    connection.setRequestMethod("GET");
                    //设置打开链接的时间
                    connection.setConnectTimeout(5000);
                    //设置读取数据返回的时间
                    connection.setReadTimeout(5000);
                    //得到状态码
                    int code = connection.getResponseCode();

                    if (code == 200){

                        InputStream is = connection.getInputStream();
                        return  getBitmap(is,url,100,100);

                    }


                } catch (Exception e) {
                    e.printStackTrace();
                }

                return null;
            }
        }.execute(url);


    }

    private Bitmap getBitmap(InputStream is,URL url,int requsetHeight,int requsetWidth){
        try {
            //将字节流转化成图片对象
            //得到图片的宽高
            BitmapFactory.Options options = new BitmapFactory.Options();
            //假解析图片
            options.inJustDecodeBounds = true;
            BitmapFactory.decodeStream(is,null,options);
            //得到采样率
            int inSampleSize = getinSampleSize(options, requsetHeight, requsetWidth);
            //将得到的采样率赋值
            options.inSampleSize = inSampleSize;
            //得到采样率后进行真解析
            options.inJustDecodeBounds = false;
            //重新打开流
            is.close();
            InputStream inputStream = url.openStream();
            //得到压缩后的图片
            Bitmap bitmap = BitmapFactory.decodeStream(inputStream,null,options);

            return  bitmap;
        } catch (IOException e) {
            e.printStackTrace();
        }

        return  null;

    }


    private int getinSampleSize(BitmapFactory.Options options,int requsetHeight,int requsetWidth){
        //得到图片的原始宽高
        int height = options.outHeight;
        int width = options.outWidth;
        //定义一个变量记录采样率
        int inSampleSize = 1;
        //判断是否在期望的宽高内
        if (height > requsetHeight || width > requsetWidth){

            int helfHeight = height / 2;
            int helfWidth = width /2;
            //计算采样率
            while (helfHeight/inSampleSize > requsetHeight && helfWidth/inSampleSize >requsetWidth){
                inSampleSize *= 2;
            }

        }

        return inSampleSize;
    }




}