HttpURLConnection下载图片的两种方式

public class MainActivity extends AppCompatActivity {

    private ImageView iv;

    private String imageurl = "http://img06.tooopen.com/images/20161106/tooopen_sl_185050524199.jpg";
    private Bitmap bitmap;

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

        iv = (ImageView) findViewById(R.id.iv_show);

        findViewById(R.id.load).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                new Thread(loadrunable).start();
            }
        });
    }

    private Runnable loadrunable = new Runnable() {

        private InputStream is;

        @Override
        public void run() {

            try {
             URL imgUrl = new URL(imageurl);
            // 使用HttpURLConnection打开连接
            HttpURLConnection urlConn = (HttpURLConnection) imgUrl
                    .openConnection();
            urlConn.setDoInput(true);
                urlConn.setDoOutput(false);
                urlConn.setRequestMethod("GET");
                urlConn.setConnectTimeout(3000);
                urlConn.setUseCaches(true);
            urlConn.connect();
                int code = urlConn.getResponseCode();
                Log.e("tag", "run: "+code );
                // 将得到的数据转化成InputStream
            InputStream is = urlConn.getInputStream();
            // 将InputStream转换成Bitmap
//            bitmap = getBitmapInputStream(is);

                byte[] bytesInputStream = getBytesInputStream(is);
                bitmap = BitmapFactory.decodeByteArray(bytesInputStream,0,bytesInputStream.length);

                    Message msgone = new Message();
                   msgone.what = 1;
                    handler.sendMessage(msgone);

            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }finally {

                if (null != is){
                    try {
                        is.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    };

    private Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
//            super.handleMessage(msg);
            Log.e("tag", "handleMessage: "+msg.what );

            if (null != bitmap && null != iv){
                iv.setImageBitmap(bitmap);
            }
        }
    };

    public Bitmap getBitmapInputStream(InputStream is){
        Bitmap bp;
        bp = BitmapFactory.decodeStream(is);

        return bp;
    }

    public byte[] getBytesInputStream( InputStream is) throws IOException {

        ByteArrayOutputStream arrayOutputStream = new ByteArrayOutputStream();
        byte[] buff = new byte[512];
        int len;
        while ((len = is.read(buff))!= -1){

            arrayOutputStream.write(buff,0,len);
        }

        is.close();
        arrayOutputStream.close();

       return arrayOutputStream.toByteArray();

    }
}

重点：不要设置setDoOutput(true)，post请求上传参数得设置为true;
它默认为false:  urlConn.setDoOutput(false);

参考博客：  http://blog.csdn.net/ameyume/article/details/6528205