图片压缩无bug版

package com.example.imageresizer;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;

import com.example.imageresizer.utils.ImageResizer;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
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);

    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(){


        @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);

}

}

计算采样率的工具类
package com.example.imageresizer.utils;

import android.graphics.BitmapFactory;

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;
}

}