二次采样实例

最新推荐文章于 2018-11-06 21:24:37 发布

原创最新推荐文章于 2018-11-06 21:24:37 发布 · 858 阅读

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#android #二次采样

这篇博客提供了一个关于Android中二次采样的简单实例，通过使用AsyncTask进行异步处理，为开发者提供参考。

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一个简单的二次采样实例,简单的代码,仅供参考,使用简单的AsyncTask实现

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.Button;
import android.widget.ImageView;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

import butterknife.ButterKnife;
import butterknife.InjectView;

public class MainActivity extends AppCompatActivity {

    @InjectView(R.id.btn_main)
    Button btnMain;
    @InjectView(R.id.iv_main)
    ImageView ivMain;

    private String imgUrl="http://img4.imgtn.bdimg.com/it/u=3432487329,2901563519&fm=26&gp=0.jpg";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ButterKnife.inject(this);
        //设置点击事件
        btnMain.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //执行
                new MyAsyncTask().execute(imgUrl);
            }
        });
    }
    class MyAsyncTask  extends AsyncTask<String ,Integer,Bitmap>{
        @Override
        protected Bitmap doInBackground(String... strings) {
            try {
                ///创建并连接
                URL url=new URL(strings[0]);
            HttpURLConnection connection= (HttpURLConnection) url.openConnection();
                connection.connect();
                if (connection.getResponseCode()==HttpURLConnection.HTTP_OK){
                    //获取输入流
                    InputStream inputStream = connection.getInputStream();
                    int len=0;
                    byte[] b=new byte[1024];
                    ByteArrayOutputStream out=new ByteArrayOutputStream();
                    while((len=inputStream.read(b))!=-1){
                        out.write(b,0,len);
                    }
                    out.flush();
                    BitmapFactory.Options options=new BitmapFactory.Options();
                    options.inJustDecodeBounds=true;
                    BitmapFactory.decodeByteArray(out.toByteArray(),0,out.size(),options);
                    float outHeight = options.outHeight;
                    float outWidth = options.outWidth;
                    int scale= (int) ((outHeight>outWidth?outHeight:outWidth)/100);
                    if (scale<=0)scale=1;
                    options.inSampleSize=1/scale;
                    options.inJustDecodeBounds=false;
                    return BitmapFactory.decodeByteArray(out.toByteArray(),0,out.size(),options);
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(Bitmap bitmap) {
            //设置图片
            ivMain.setImageBitmap(bitmap);
        }
    }
}