分享程序员开发的那些事...
更新时间：2022-08-16 14:39:42
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。