使用AsyncTask从网上获取一个网页，在一个TextView中将其源代码显示出来

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使用AsyncTask从网上获取一个网页，在一个TextView中将其源代码显示出来

package test.list;import java.io.ByteArrayOutputStream;import java.io.InputStream;import java.util.ArrayList;import org.apache.http.HttpEntity;import org.apache.http.HttpResponse;import org.apache.http.client.HttpClient;import org.apache.http.client.methods.HttpGet;import org.apache.http.impl.client.DefaultHttpClient;import android.app.Activity;import android.app.ProgressDialog;import android.content.Context;import android.content.DialogInterface;import android.os.AsyncTask;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;public class NetworkActivity extends Activity{    private TextView message;    private Button open;    private EditText url;    @Override    public void onCreate(Bundle savedInstanceState) {       super.onCreate(savedInstanceState);       setContentView(R.layout.network);       message= (TextView) findViewById(R.id.message);       url= (EditText) findViewById(R.id.url);       open= (Button) findViewById(R.id.open);       open.setOnClickListener(new View.OnClickListener() {           public void onClick(View arg0) {              connect();           }       });    }    private void connect() {        PageTask task = new PageTask(this);        task.execute(url.getText().toString());    }    class PageTask extends AsyncTask<String, Integer, String> {        // 可变长的输入参数，与AsyncTask.exucute()对应        ProgressDialog pdialog;        public PageTask(Context context){            pdialog = new ProgressDialog(context, 0);               pdialog.setButton("cancel", new DialogInterface.OnClickListener() {             public void onClick(DialogInterface dialog, int i) {              dialog.cancel();             }            });            pdialog.setOnCancelListener(new DialogInterface.OnCancelListener() {             public void onCancel(DialogInterface dialog) {              finish();             }            });            pdialog.setCancelable(true);            pdialog.setMax(100);            pdialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);            pdialog.show();        }        @Override        protected String doInBackground(String... params) {            try{               HttpClient client = new DefaultHttpClient();               // params[0]代表连接的url               HttpGet get = new HttpGet(params[0]);               HttpResponse response = client.execute(get);               HttpEntity entity = response.getEntity();               long length = entity.getContentLength();               InputStream is = entity.getContent();               String s = null;               if(is != null) {                   ByteArrayOutputStream baos = new ByteArrayOutputStream();                   byte[] buf = new byte[128];                   int ch = -1;                   int count = 0;                   while((ch = is.read(buf)) != -1) {                      baos.write(buf, 0, ch);                      count += ch;                      if(length > 0) {                          // 如果知道响应的长度，调用publishProgress（）更新进度                          publishProgress((int) ((count / (float) length) * 100));                      }                      // 让线程休眠100ms                      Thread.sleep(100);                   }                   s = new String(baos.toByteArray());              }               // 返回结果               return s;            } catch(Exception e) {               e.printStackTrace();            }            return null;        }        @Override        protected void onCancelled() {            super.onCancelled();        }        @Override        protected void onPostExecute(String result) {            // 返回HTML页面的内容            message.setText(result);            pdialog.dismiss();         }        @Override        protected void onPreExecute() {            // 任务启动，可以在这里显示一个对话框，这里简单处理            message.setText(R.string.task_started);        }        @Override        protected void onProgressUpdate(Integer... values) {            // 更新进度              System.out.println(""+values[0]);              message.setText(""+values[0]);              pdialog.setProgress(values[0]);        }     }}
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