源代码如下

package com.example.asynctask;import android.app.ProgressDialog;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.AsyncTask;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.util.Log;import android.view.View;import android.widget.Button;import android.widget.ImageView;import java.io.ByteArrayOutputStream;import java.io.IOException;import java.io.InputStream;import java.net.HttpURLConnection;import java.net.MalformedURLException;import java.net.URL;public class MainActivity extends AppCompatActivity {     Button button;     ImageView imageView;     ProgressDialog progressDialog;     String IMAGE_PATH="http://image.baidu.com/search/redirect?tn=redirect&word=j&juid=51AEAB&sign=cibzwikaba&url=http%3A%2F%2Flife.northnews.cn%2F2015%2F0515%2F1927051_20.shtml&objurl=http%3A%2F%2Fupload.northnews.cn%2F2015%2F0515%2F1431655212431.jpg";    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        button = (Button) findViewById(R.id.button);        imageView = (ImageView) findViewById(R.id.image);        progressDialog = new ProgressDialog(MainActivity.this);        progressDialog.setTitle("提示信息");        progressDialog.setCancelable(false);        progressDialog.setMessage("正在下载中，请稍后。。。");        progressDialog.setProgressStyle(progressDialog.STYLE_HORIZONTAL);        button.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                new MyAsyncTask().execute(IMAGE_PATH); }        }) ;    }    public class MyAsyncTask extends AsyncTask
     
      {        @Override        protected void onPreExecute() {
   super.onPreExecute();            progressDialog.show(); }        @Override        protected byte[] doInBackground(String... strings) {            byte[] image = new byte[]{};            HttpURLConnection connection = null;            InputStream inputStream = null;            ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();            Log.i("test","    =====    ");            try {                URL url = new URL(strings[0]);                connection = (HttpURLConnection) url.openConnection();                if (connection.getResponseCode()==200){                    file_length = connection.getContentLength();                    long totle_length = 0;                    int length = 0;                    byte[] data = new byte[1024];                    inputStream = connection.getInputStream();                    while (-1 !=(length = inputStream.read(data))){                        totle_length += length;                        byteArrayOutputStream.write(data,0,length);                        int progress = ((int)(totle_length*100/(float)file_length));                        publishProgress(progress);                        try {                            Thread.sleep(1000);                        } catch (InterruptedException e) {                            e.printStackTrace();                        }                    }                    Log.i("test","-----");                    image = byteArrayOutputStream.toByteArray();                    inputStream.close();                    byteArrayOutputStream.close();                }            } catch (MalformedURLException e) {                e.printStackTrace();            } catch (IOException e) {                e.printStackTrace();            }finally {                connection.disconnect();            }return image;        }        @Override        protected void onProgressUpdate(Integer... values) {            super.onProgressUpdate(values);            progressDialog.setProgress(values[0]);}        @Override        protected void onPostExecute(byte[] bytes) {            super.onPostExecute(bytes);            Bitmap bitmap = BitmapFactory.decodeByteArray(bytes,0,bytes.length);            imageView.setImageBitmap(bitmap);            progressDialog.dismiss();        }    }}
     

存在的问题：

1.不是所有代码都简单易懂 ，代码的变量名没有注意到，有的可能没加

2.不太符合编程规范。大括号的位置有的随意乱放，只要没有出现错误就行。基本没有注释   

3.可能存在多余的代码  

4.代码没有尽可能的模块化