android *** AsyncTask 代码

http://android-doc.com/reference/android/os/AsyncTask.html

xml

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    xmlns:android1="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context="${relativePackage}.${activityClass}" >    <ImageView        android1:id="@+id/imageView1"        android1:layout_width="wrap_content"        android1:layout_height="wrap_content"        android1:layout_alignParentLeft="true"        android1:layout_alignParentTop="true"        android1:layout_marginLeft="78dp"        android1:layout_marginTop="180dp" />    <Button        android1:id="@+id/button1"        android1:layout_width="wrap_content"        android1:layout_height="wrap_content"        android1:layout_alignParentBottom="true"        android1:layout_marginBottom="78dp"        android1:layout_toRightOf="@+id/imageView1"        android1:text="下载图片" /></RelativeLayout>

java

package com.example.tree;import android.support.v7.app.ActionBarActivity;import android.text.Html;import android.text.Spanned;import android.text.method.LinkMovementMethod;import android.util.Log;import java.io.ByteArrayOutputStream;import java.io.IOException;import java.io.InputStream;import java.util.ArrayList;import java.util.Calendar;import java.util.List;import org.apache.http.HttpResponse;import org.apache.http.client.ClientProtocolException;import org.apache.http.client.HttpClient;import org.apache.http.client.methods.HttpGet;import org.apache.http.impl.client.DefaultHttpClient;import org.apache.http.util.EntityUtils;import android.app.AlertDialog;import android.app.DatePickerDialog;import android.app.DatePickerDialog.OnDateSetListener;import android.app.ProgressDialog;import android.app.TimePickerDialog;import android.app.TimePickerDialog.OnTimeSetListener;import android.content.Context;import android.content.DialogInterface;import android.content.Intent;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.drawable.Drawable;import android.os.AsyncTask;import android.os.Bundle;import android.view.*;import android.view.View.OnClickListener;import android.view.View.OnKeyListener;import android.widget.AdapterView;import android.widget.AdapterView.OnItemSelectedListener;import android.widget.AnalogClock;import android.widget.ArrayAdapter;import android.widget.AutoCompleteTextView;import android.widget.BaseAdapter;import android.widget.Button;import android.widget.CheckBox;import android.widget.DatePicker;import android.widget.EditText;import android.widget.ImageView;import android.widget.LinearLayout;import android.widget.ListView;import android.widget.ProgressBar;import android.widget.RatingBar;import android.widget.RatingBar.OnRatingBarChangeListener;import android.widget.ScrollView;import android.widget.SeekBar;import android.widget.SeekBar.OnSeekBarChangeListener;import android.widget.Spinner;import android.widget.TextView;import android.widget.TimePicker;import android.widget.TimePicker.OnTimeChangedListener;import android.widget.Toast;public class MainActivity extends ActionBarActivity {private Button button;private ImageView imageView;private final String IMAGE_PATH="http://www.baidu.com/img/bdlogo.gif";private ProgressDialog dialog;private final String TAG="MainActivity";@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);Log.i(TAG, "-onCreate-->>");button=(Button)this.findViewById(R.id.button1);imageView=(ImageView)this.findViewById(R.id.imageView1);dialog=new ProgressDialog(MainActivity.this);dialog.setTitle("提示框");dialog.setMessage("正在下载图片，请稍后...");dialog.setCancelable(false);dialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);button.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v) {// TODO Auto-generated method stubnew MyTask().execute(IMAGE_PATH);}});}class MyTask extends AsyncTask<String,Integer,byte[]>{@Overrideprotected void onPreExecute(){super.onPreExecute();dialog.show();}@Overrideprotected byte[] doInBackground(String... params) {// TODO Auto-generated method stubHttpClient httpClient=new DefaultHttpClient();HttpGet httpGet=new HttpGet(params[0]);byte[] result=null;InputStream inputStream=null;ByteArrayOutputStream outputStream=new ByteArrayOutputStream();try {HttpResponse httpResponse = httpClient.execute(httpGet);long file_length=httpResponse.getEntity().getContentLength();//文件总长度int total_length=0;byte[] data=new byte[1024];int len=0;if(httpResponse.getStatusLine().getStatusCode()==200){//result=EntityUtils.toByteArray(httpResponse.getEntity());inputStream=httpResponse.getEntity().getContent();while((len=inputStream.read(data))!=-1){total_length+=len;int progress_value=(int)((total_length/(float)file_length)*100);publishProgress(progress_value);outputStream.write(data, 0, len);}}result=outputStream.toByteArray();} catch (ClientProtocolException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{httpClient.getConnectionManager().shutdown();}return result;}protected void onProgressUpdate(Integer...values){super.onProgressUpdate(values);dialog.setProgress(values[0]);}protected void onPostExecute(byte[] result){super.onPostExecute(result);Bitmap bitmap=BitmapFactory.decodeByteArray(result, 0, result.length);imageView.setImageBitmap(bitmap);dialog.dismiss();}}protected void onStart(){super.onStart();Log.i(TAG, "-onStart-->>");}protected void onRestart(){super.onRestart();Log.i(TAG, "-onRestart-->>");}protected void onResume(){super.onResume();Log.i(TAG, "-onResume-->>");}protected void onPause(){super.onPause();Log.i(TAG, "-onPause-->>");}protected void onStop(){super.onStop();Log.i(TAG, "-onStop-->>");}protected void onDestroy(){super.onDestroy();Log.i(TAG, "-onDestroy-->>");}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}@Overridepublic boolean onOptionsItemSelected(MenuItem item) {// Handle action bar item clicks here. The action bar will// automatically handle clicks on the Home/Up button, so long// as you specify a parent activity in AndroidManifest.xml.int id = item.getItemId();if (id == R.id.action_settings) {return true;}return super.onOptionsItemSelected(item);}}