计算图片采样率压缩图片

1：创建工具类，用来计算采样率

public class ImageResizer {

    /**
     * 计算采样率
     * @param options
     * @param requestWidth
     * @param requestHeight
     * @return
     */
    public static int calculateInSampleSize(BitmapFactory.Options options,int requestWidth,int requestHeight){

        //获取图片的真实的宽高
        int width = options.outWidth;
        int height = options.outHeight;

        int inSampleSize = 1;
        options.inSampleSize = inSampleSize;//默认 1  1代表不对图片进行任何压缩
        //计算采样率
        if(width > requestWidth || height > requestHeight){

            int halfWidth = width / 2;
            int halfHeight = height / 2;

            while((halfWidth / inSampleSize) >= requestWidth &&
                    (halfHeight / inSampleSize) >= requestHeight){
                //计算采样率
                inSampleSize *= 2;
            }

        }
        return inSampleSize;
    }

}

2：调用

下面是在AsyncTask方法里调用的该工具类注意doInBackground方法即可

public class MainActivity extends AppCompatActivity {

    private ImageView ivIcon;

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

        ivIcon = (ImageView) findViewById(R.id.ivIcon);

    }



    public void btnLoadImge(View v){
        loadImage("http://20.1.4.181:8080/beautiful.jpg",100,100);


    }

    /**
     * 加载图片，并压缩
     * @param imgPath
     * @param requestWidth
     * @param requestHeight
     */
    public void loadImage(String imgPath, final int requestWidth, final int requestHeight){


        new AsyncTask<String,Void,Bitmap>(){


            @Override
            protected void onPostExecute(Bitmap bitmap) {
                super.onPostExecute(bitmap);
                if(bitmap != null){
                    ivIcon.setImageBitmap(bitmap);
                }
            }
            @Override
            protected Bitmap doInBackground(String... params) {


                try {
                    //得到图片路径
                    String path = params[0];
                    URL url = new URL(path);
                    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                    connection.setRequestMethod("GET");
                    connection.setConnectTimeout(5000);
                    connection.setReadTimeout(5000);
                    connection.setDoInput(true);
                    connection.setDoOutput(true);
                    int code = connection.getResponseCode();

                    if(code == 200){
                        //得到图片流
                       InputStream is = connection.getInputStream();
                        //解析图片
                        BitmapFactory.Options options = new BitmapFactory.Options();
                        //让图片暂时不去解析 只需要获取图片的宽高
                        options.inJustDecodeBounds = true;
                        //解析一下图片，这个时候，只会解析图片的宽*高
                        BitmapFactory.decodeStream(is,null,options);
                        //计算采样率
                        options.inSampleSize = ImageResizer.calculateInSampleSize(options,requestWidth,requestHeight);
                        //我这时候需要真正去解析图片
                        options.inJustDecodeBounds = false;
                        //关闭流
                        is.close();
                        //得到图片的输入流
                        is = url.openStream();
                        //解析图片的时候，才会去真正解析
                        Bitmap bitmap = BitmapFactory.decodeStream(is,null,options);
                        //关闭流
                        is.close();
                        return bitmap;


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


                return null;
            }
        }.execute(imgPath);


    }




}