Android：仿微博Listview与多线程功能(JSON、数据下载、图片加载、Listview、异步任务)
解析服务端JSON的内容和图片，通过异步任务下载并设置到listview页上，点击listview跳转到详情页。 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 public class WatchingActivity extends Activity implements OnClickListener, OnItemClickListener { private ListView mListView; private HashMap<URL, Bitmap> mCacheMap = new HashMap<URL, Bitmap>(); private View errorView; private View loadingview; private RelativeLayout errorlayout; private Button btn_netRetry; private View headview; private View footview; private View btn_footviewloading; private TextView btn_loadmore; private int mPage = 1 ; private BaseAdapter mAdapter; private ArrayList<ItemData> mDataList = new ArrayList<ItemData>(); private View headviewad; private View imageBtn_refresh; /* * 创建布局 * 下载内容 * 解析内容 * 下载图片 * 图片缓存 * 网络错误页面 * 网络加载页面 * 增加页眉 * 加载更多 * 页眉响应 * ListView行跳转 * 内容页显示详情 */ /** * 1.适配器判断是否为空，生命周期？还是因为是第一次===========> 复用会导致数据重新刷新，不能在原有数据基础上加载 * 2.页眉整张图片，则无法直接点击------------------->layout拦截掉了监听 * 3.加载更多链接不在时result会报错空值---------------> * 4.mListView.setOnItemClickListener(this);用这个方法监听ListView无效?========>监听行布局对象 * 5.顶部刷新按钮为何不响应？ * 6.行布局的进度条为何找不到？========>已解决 * 7.include移位就报错==============>没问题 * 8.控件层次如何改变=============> relative根据xml代码位置 * 9.setonItemClick position要减1才能对应？============> 加完headview后，position初始值自动加1 * */ class ItemData { String imageUrl; String title; String from; String time; String content; public ItemData(String imageUrl, String title, String from, String time, String content) { super (); this .imageUrl = imageUrl; this .title = title; this .from = from; this .time = time; this .content = content; } } class ViewHolder { ImageView imageView; TextView textView_title; TextView textView_from; TextView textView_time; ProgressBar progressBar_imageLoading; } @Override protected void onCreate(Bundle savedInstanceState) { super .onCreate(savedInstanceState); setContentView(R.layout.activity_watching); setUI(); } private void setUI() { LayoutInflater inflater = getLayoutInflater(); headview = inflater.inflate(R.layout.headview, null ); footview = inflater.inflate(R.layout.footview, null ); btn_footviewloading = footview.findViewById(R.id.footview_loading); btn_loadmore = (TextView) footview.findViewById(R.id.btn_loadmore); headviewad = headview.findViewById(R.id.imageView_headview_ad); imageBtn_refresh = findViewById(R.id.imageBtn_refresh); btn_netRetry = (Button) findViewById(R.id.btn_netRetry); loadingview = findViewById(R.id.loadingview); errorView = findViewById(R.id.errorview); mListView = (ListView) findViewById(R.id.listView_watching); mListView.addHeaderView(headview); //注意：一定要在setAdapter之前调用,所以一般在找到listview之后就添加 mListView.addFooterView(footview); loadTask(); //网络连接重试按钮 btn_netRetry.setOnClickListener( this ); //分页加载更多 btn_loadmore.setOnClickListener( this ); //点击ListView页眉广告 headviewad.setOnClickListener( this ); //点击顶部刷新页面 btn_netRetry.setOnClickListener( this ); //点击listview跳转 mListView.setOnItemClickListener( this ); } //按钮点击事件 @Override public void onClick(View v) { switch (v.getId()) { case R.id.btn_netRetry: errorView.setVisibility(View.GONE); mPage = 1 ; loadTask(); break ; case R.id.btn_loadmore: btn_loadmore.setVisibility(View.INVISIBLE); btn_footviewloading.setVisibility(View.VISIBLE); loadTask(); break ; case R.id.imageView_headview_ad: Toast.makeText(WatchingActivity. this , Contant.HEADVIEW_TOAST, Toast.LENGTH_LONG).show(); break ; case R.id.imageBtn_refresh: loadTask(); break ; default : break ; } } //监听listview @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { if (view.getId() == R.id.watching_item) //监听的对象是行布局 { Intent intent = new Intent(WatchingActivity. this , ContentActivity. class ); ItemData data = mDataList.get(position - 1 ); String fromtime = data.from + " " + Contant.TIME_YEAR + data.time; intent.putExtra(Contant.KEY_INTENTER_TITLE, data.title); intent.putExtra(Contant.KEY_INTENTER_FROMTIME, fromtime); intent.putExtra(Contant.KEY_INTENTER_CONTENT, data.content); startActivity(intent); } } //启动异步任务 private void loadTask() { URL dataUrl = null ; try { dataUrl = new URL(Contant.URL_DATA + mPage + Contant.URL_DATA_FILEFORM); // 异步任务下载数据 LoadDataTask loadDataTask = new LoadDataTask(); loadDataTask.execute(dataUrl); } catch (MalformedURLException e) { e.printStackTrace(); } } // 异步任务下载数据 class LoadDataTask extends AsyncTask<URL, Void, String> { @Override protected void onPreExecute() { loadingview.setVisibility(View.VISIBLE); } @Override protected String doInURL... params) { InputStream is = null ; ByteArrayBuffer strBuf = new ByteArrayBuffer( 59658 ); //使用ByteArrayBuffer，直接使用String可能造成读取到的部分内容乱码 try { HttpURLConnection conn = (HttpURLConnection) params[ 0 ].openConnection(); conn.setConnectTimeout(Contant.HTTP_TIME_OUT); conn.setReadTimeout(Contant.HTTP_TIME_OUT); // 判断网络连接是否正常 if (conn.getResponseCode() != HttpURLConnection.HTTP_OK) { //返回错误提示页面 return null ; } // 下载数据 is = conn.getInputStream(); byte [] buf = new byte [ 1024 ]; int len = 0 ; while (- 1 != (len = is.read(buf))) { strBuf.append(buf, 0 , len); //直接加入ByteArrayBuffer } } catch (IOException e) { e.printStackTrace(); } finally { if (is != null ) { try { is.close(); } catch (IOException e) { e.printStackTrace(); } } } return new String(strBuf.buffer()); //bytebuffer数组转成字符串 } // 下载数据解析，更新控件内容 @Override protected void onPostExecute(String result) { loadingview.setVisibility(View.GONE); //判断result是否为空 if (TextUtils.isEmpty(result.trim())) { btn_loadmore.setVisibility(View.GONE); errorView.setVisibility(View.VISIBLE); mListView.setVisibility(View.GONE); // return; } else { btn_loadmore.setVisibility(View.VISIBLE); btn_footviewloading.setVisibility(View.INVISIBLE); mListView.setVisibility(View.VISIBLE); // 解析json数据 ArrayList<ItemData> dataList = parse(result); //更新控件内容 setListData(dataList); } } } //更新行内容 private void setListData(ArrayList<ItemData> dataList) { //判断mAdapter是否为空，复用mAdapter实现内容加载，重新set会导致所有内容重新加载(跳到第一行) if ( null == mAdapter) { createAdapter(dataList); //创建适配器 mListView.setAdapter(mAdapter); } else { mAdapter.notifyDataSetChanged(); //通知listview更新界面 } } // 解析json数据 private ArrayList<ItemData> parse(String result) { try { JSONArray jsonArray = new JSONArray(result); mPage++; //数据解析完成后，页数修改 for ( int i = 0 ; i < jsonArray.length(); i++) { JSONObject jsonObject = jsonArray.getJSONObject(i); String imageUrl = Contant.URL_HOST + jsonObject.getString(Contant.KEY_JSON_IMGURL); String title = jsonObject.getString(Contant.KEY_JSON_TITLE); String from = jsonObject.getString(Contant.KEY_JSON_FROM); String time = jsonObject.getString(Contant.KEY_JSON_TIME); String content = jsonObject.getString(Contant.KEY_JSON_CONTENT); ItemData itemData = new ItemData(imageUrl, title, from, time,content); mDataList.add(itemData); } } catch (JSONException e) { e.printStackTrace(); } return mDataList; } //创建Adapter,设置LiseView private void createAdapter( final ArrayList<ItemData> dataList) { mAdapter = new BaseAdapter() { @Override public View getView( int position, View convertView,ViewGroup parent) { ViewHolder holder; if (convertView == null ) { LayoutInflater inflater = getLayoutInflater(); convertView = inflater.inflate(R.layout.watch_layout, null ); holder = new ViewHolder(); holder.imageView = (ImageView) convertView.findViewById(R.id.imgView_watch_newspic); holder.textView_title = (TextView) convertView.findViewById(R.id.txtView_watch_title); holder.textView_from = (TextView) convertView.findViewById(R.id.txtView_from); holder.textView_time = (TextView) convertView.findViewById(R.id.txtView_time); holder.progressBar_imageLoading = (ProgressBar) convertView.findViewById(R.id.progressBar_imageloading); convertView.setTag(holder); } else { holder = (ViewHolder) convertView.getTag(); } ItemData itemData = dataList.get(position); //启动图片下载任务 try { URL url = new URL(itemData.imageUrl); if (mCacheMap.containsKey(url)) { holder.imageView.setImageBitmap(mCacheMap.get(url)); } else { LoadImageTask imageTask = new LoadImageTask(holder.imageView,holder.progressBar_imageLoading); imageTask.execute(url); } } catch (MalformedURLException e) { e.printStackTrace(); } holder.textView_title.setText(itemData.title); holder.textView_from.setText(itemData.from); holder.textView_time.setText(itemData.time); return convertView; } @Override public long getItemId( int position) { return 0 ; } @Override public Object getItem( int position) { return null ; } @Override public int getCount() { return dataList.size(); } }; } //下载图片 class LoadImageTask extends AsyncTask<URL, Void, Bitmap> { private ImageView imageView; ProgressBar progressBar_imageLoading; public LoadImageTask(ImageView imageView, ProgressBar progressBar_imageLoading) { this .imageView = imageView; this .progressBar_imageLoading = progressBar_imageLoading; } @Override protected void onPreExecute() { progressBar_imageLoading.setVisibility(View.VISIBLE); } //下载图片 @Override protected Bitmap doInURL... params) { InputStream is = null ; Bitmap bitmap = null ; try { //判断网络连接 HttpURLConnection conn = (HttpURLConnection) params[ 0 ].openConnection(); conn.setConnectTimeout(Contant.HTTP_TIME_OUT); conn.setReadTimeout(Contant.HTTP_TIME_OUT); if (conn.getResponseCode() != HttpURLConnection.HTTP_OK) { return null ; } //由url获取bitmap对象 is = conn.getInputStream(); //简写方法:is = params[0].openStream() bitmap = BitmapFactory.decodeStream(is); mCacheMap.put(params[ 0 ], bitmap); } catch (IOException e) { e.printStackTrace(); } finally { if ( null != is ) { try { is.close(); } catch (IOException e) { e.printStackTrace(); } } } return bitmap; } @Override protected void onPostExecute(Bitmap bitmap) { if (bitmap == null ) { //图片加载失败 } else { progressBar_imageLoading.setVisibility(View.INVISIBLE); imageView.setImageBitmap(bitmap); } } } @Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.watching, menu); return true ; } } 其他优化和扩展： 1.图片加载 与设置图片方法一样，将控件对象传到异步任务里 2.惰性加载 其他相关: 1.隐藏headview 1 2 3 4 5 6 7 8 9 <LinearLayout android:id= "@+id/item_root" android:layout_width= "fill_parent" android:layout_height= "50dip" android:orientation= "vertical" > <LinearLayout android:id= "@+id/item_container" <TextView android:id= "@+id/tv_1" /> <TextView android:id= "@+id/tv_2" /> </LinearLayout> </LinearLayout > 要隐藏的view必须不能是根目录的view的id。 本文转自 glblong 51CTO博客，原文链接：http://blog.51cto.com/glblong/1215407，如需转载请自行联系原作者
