代码片--Android--图片下载进度条

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public class MainActivity extends ActionBarActivity {    Button b;    ImageView i;    ProgressDialog p;//进度条    String path="http://pic.nipic.com/2007-12-23/200712231523651_2.jpg";//图片地址    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        b = (Button) findViewById(R.id.button1);        i = (ImageView) findViewById(R.id.imageView1);        p = new ProgressDialog(this);        p.setTitle("提示信息");        p.setMessage("下载中，请稍后...");        p.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);//设置进度样式        b.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                // TODO Auto-generated method stub                new MyTask().execute(path);//启动AsyncTask            }        });    }//第一个参数是路径//第二个参数是进度刻度//但三个参数是返回类型    class MyTask extends AsyncTask<String, Integer, Bitmap> {//准备阶段，一般显示进度条        @Override        protected void onPreExecute() {            // TODO Auto-generated method stub            super.onPreExecute();            p.show();        }//后台长时间跑的逻辑业务        @Override        protected Bitmap doInBackground(String... params) {            // TODO Auto-generated method stub            Bitmap bp=null;            InputStream in=null;            ByteArrayOutputStream bo=new ByteArrayOutputStream();            //设置Http协议访问            HttpClient httpClient=new DefaultHttpClient();            HttpGet httpGet =new HttpGet(params[0]);            try {                HttpResponse httpResponse=httpClient.execute(httpGet);                //当Http请求成功返回                if(httpResponse.getStatusLine().getStatusCode()==200){                    in=httpResponse.getEntity().getContent();//通过流得到实体内容                    long file_length=httpResponse.getEntity().getContentLength();//得到文件总容量                    int len=0;//每次读取长度                    int total_length=0;//已读取总长                    byte[] data=new byte[1024];                    while ((len=in.read(data))!=-1) {                        total_length+=len;                        int value= (int) ((total_length/(float)file_length)*100);                        publishProgress(value);                        bo.write(data, 0, len);                    }                    byte[] result=bo.toByteArray();                    bp=BitmapFactory.decodeByteArray(result, 0, result.length);                }            } catch (ClientProtocolException e) {                // TODO Auto-generated catch block                e.printStackTrace();            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }//对各种流关闭            finally{                if(in!=null){                    try {                        in.close();                    } catch (IOException e) {                        // TODO Auto-generated catch block                        e.printStackTrace();                    }                }                if(bo!=null){                    try {                        bo.close();                    } catch (IOException e) {                        // TODO Auto-generated catch block                        e.printStackTrace();                    }                }            }            return bp;        }//时时更新UI进度条        @Override        protected void onProgressUpdate(Integer... values) {            // TODO Auto-generated method stub            super.onProgressUpdate(values);            p.setProgress(values[0]);        }//doInBackground方法结束后执行此方法，对UI做最后更新        @Override        protected void onPostExecute(Bitmap result) {            // TODO Auto-generated method stub            super.onPostExecute(result);            p.dismiss();            i.setImageBitmap(result);        }    }}
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