android实践项目八做一个下载读条

用progressBar做一个下载读条

布局文件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context="com.example.httpclientexample.MainActivity" >    <Button  android:id="@+id/btn1" android:layout_width="match_parent" android:layout_height="wrap_content" android:onClick="start" android:text="start" />  <ProgressBar  android:id="@+id/progressBar1" style="?android:attr/progressBarStyleHorizontal" android:layout_width="match_parent" android:layout_height="wrap_content" /><TextView android:id="@+id/text1" android:layout_width="match_parent" android:layout_height="wrap_content" /></LinearLayout>

代码

public class MainActivity extends Activity {    private ProgressBar progress;    private TextView text;    private Button btn;    int Processvalue;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        text = (TextView) findViewById(R.id.text1);        progress = (ProgressBar) findViewById(R.id.progressBar1);        progress.setVisibility(View.INVISIBLE);    }    public void start(View view) {        uzi();        getView();    }    private void getView() {        // TODO Auto-generated method stub    }    private void uzi() {        // TODO Auto-generated method stub        // 第三个参数是结果类型        new AsyncTask<String, Integer, String>() {            // 此方法必须重写，异步执行后台线程需要完成的任务            @Override            protected String doInBackground(String... params) {                for (int i = 0; i <= 100; i++) {                    try {                        Thread.sleep(100);                    } catch (InterruptedException e) {                        // TODO Auto-generated catch block                        e.printStackTrace();                    }                    Processvalue = i;                    publishProgress(Processvalue);                }                return null;            }            // 执行后台耗时操作时前被调用，通常用来完成一些初始化操作            @Override            protected void onPreExecute() {                super.onPreExecute();                progress.setVisibility(View.VISIBLE);                progress.setMax(100);                progress.setProgress(0);            }            // 当doinBackground()完成过后，系统自动调用，并将方法的返            // 回值传给onpostexecute()可运行在主线程操作ui            @Override            protected void onPostExecute(String result) {                // TODO Auto-generated method stub                super.onPostExecute(result);                progress.setVisibility(View.INVISIBLE);            }            // doinBackground()方法中调用publishProgress()方法更行任务的执行进度后，就会触发该方法            @Override            protected void onProgressUpdate(Integer... values) {                // TODO Auto-generated method stub                super.onProgressUpdate(values);                int value = values[0];                text.setText("当前进度" + value + "%");                progress.setProgress(value);            }            @Override            protected void onCancelled(String result) {                // TODO Auto-generated method stub                super.onCancelled(result);            }            @Override            protected void onCancelled() {                // TODO Auto-generated method stub                super.onCancelled();            }        }.execute();    }}

用AsyncTask实现效果。。。。

用progressBar做一个下载读条

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