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![AsyncTask 實作
if (lat != null lng != null) {
String url = ...;
new AsyncTaskString, Void, Drawable() {
@Override
protected Drawable doInBackground(String... params) {
try {
InputStream is = new URL(params[0]).openStream();
return Drawable.createFromStream(is, src);
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Drawable result) {
if (result != null) {
imageView1.setImageDrawable(result);
}
super.onPostExecute(result);
}
}.execute(url);
}](https://image.slidesharecdn.com/android-141024003704-conversion-gate01/85/Android-67-320.jpg)
![存取 HTTP Web Services
protected String doInBackground(String... params) {
try {
BufferedReader reader = new BufferedReader(
new InputStreamReader(new URL(params[0]).openStream()));
String json = reader.readLine();
reader.close();
return json;
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}](https://image.slidesharecdn.com/android-141024003704-conversion-gate01/85/Android-75-320.jpg)
![doInBackground
@Override
protected String doInBackground(String... params) {
try {
InputStream stream = new URL(params[0]).openStream();
InputStreamReader isr = new InputStreamReader(stream, UTF-8);
BufferedReader reader = new BufferedReader(isr);
String json = reader.readLine();
return json;
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}](https://image.slidesharecdn.com/android-141024003704-conversion-gate01/85/Android-86-320.jpg)
Uploaded byKyle Lin
Android 智慧型手機程式設計
本文件介绍了Android应用程序开发的基础知识，包括开发环境的设置、用户界面的设计方法、按钮和事件处理、以及调试和日志记录。它详细说明了使用Intent进行页面跳转和使用AsyncTask处理多线程操作。同时文档还提供了与网络交互的示例，如获取天气信息和执行网络请求。
Android 智慧型手機程式設計
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- 2.
- 3. ADT Bundle • developer.android.com/sdk •Eclipse IDE with built-in ADT (Android DeveloperTools)
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- 5. Android Screen Monitor http://goo.gl/mnMeaS java-jar asm.jar ctrl + 1 = 100% ctrl + 7 = 75% ctrl + 5 = 50% 縮放 執⾏行
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- 7. 線上免費課程 from Coursera ProgrammingMobile Applications for Android Handheld Systems
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- 15. UI 的設計⽅方式 • 程序式（procedural） 在程式碼動態產⽣生畫⾯面UI 元件 • 宣告式（declarative） 在 Layout XML 定義畫⾯面 UI 元件
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- 27. Create a newAndroid Project • Target SDK:Android 4.x • Using Blank Activity
- 28. 設定 API Level •編輯AndroidManifest.xml • 設定 API Level 版本代號 uses-sdk android:minSdkVersion=16 android:targetSdkVersion=16 /
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- 30. • Change Layout= LinearLayout • Add RadioButton • Add Button • AddTextView
- 31. 畫⾯面佈置 • 修改 res/layout/activity_main.xml •調整 layout_width 為 fill_parent Button android:id=@+id/button1 android:layout_width=fill_parent android:layout_height=wrap_content android:onClick=showLocation android:text=查詢地點 /
- 32. • Wrap RadioButtons with RadioGroup
- 33. Click Event 1 2 3 Button ...android:onClick=“clickOpenMap” ... public void clickOpenMap(View view) { ... button1.setOnClickListener(new Button.OnClickListener() { ... 4 class MyButtonListener implements OnClickListener public class MainActivity extends Activity implements OnClickListener 按鈕點擊事件的四種處理⽅方式
- 34. 使⽤用 OnClickListener 類別 1.button1.setOnClickListener(new Button.OnClickListener() { 2. @Override 3. public void onClick(View v) { 4. ... 5. } 6. }); 按鈕點擊後會執⾏行 onClick() ⽅方法
- 35. Show Location inTextView 1.public void showLocation(View view) { 2. switch (radioGroup1.getCheckedRadioButtonId()) { 3. case R.id.radioButton1: 4. textView1.setText(澄清湖的位置是 22.660665,120.3509745); 5. break; 6. case R.id.radioButton2: 7. textView1.setText(⻄西⼦子灣的位置是 22.629167,120.262778); 8. break; 9. } 10.}
- 36. Intent 1. Intent intent= new Intent(); 2. intent.setClass( 3. MainActivity.this, 4. MainActivity2.class); 5. startActivity(intent); 參考資料 • http://ccckmit.wikidot.com/ga:intentexample
- 37. 常⾒見的 Intent ⽤用法 •http://google.com • geo:22.660,120.350 • tel: 0800080123 打開網站 打開地圖 撥打電話
- 38. Open Map withIntent 1. public void openMap(View view) { 2. Uri uri; 3. Intent intent; 4. switch (radioGroup1.getCheckedRadioButtonId()) { 5. case R.id.radioButton1: 6. uri = Uri.parse(geo:22.660,120.350); 7. intent = new Intent(Intent.ACTION_VIEW, uri); 8. startActivity(intent); 9. break; 10. } 11.}
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- 44. Dialog Example 1. AlertDialog.Builderbuilder; 2. builder = new AlertDialog.Builder(view.getContext()); 4. builder 5. .setTitle(“Something Wrong) 6. .setMessage(“Incorrect value, try again.”) 7. .setNeutralButton(OK, null) 8. .create() 9. .show(); }builder style
- 45. Toast Toast.makeText(view.getContext(), You've 3messages., Toast.LENGTH_LONG); message body 停留時間彈出後過幾秒⾃自動消失
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- 47. 輸出除錯訊息 System.out.println Log.println tagpriority 使⽤用標準輸出（stdout） 使⽤用 Android系統的 Log 機制 缺點：無法對訊息進⼀一步分類
- 48. 訊息類型 PRIORITY 名稱 ⽤用途 DEBUG僅供除錯 INFORMATION ⼀一般訊息 WARNING 資料或處理異常 ERROR 嚴重的錯誤；可能導致程式終⽌止
- 49. 使⽤用 Log 類別 Log.println(Log.WARN,MyActivity, User account not exists.); tagpriority message body
- 50. Tag 的命名慣例 public classMainActivity extends Activity { private static final String TAG = MainActivity; Log.println(Log.WARN, TAG, User account not exists.); … 通常使⽤用該記錄存在的類別名稱（Class Name）
- 51. Log 類別提供的⽅方法簡寫 • v(String,String) (verbose) • d(String, String) (debug) • i(String, String) (information) • w(String, String) (warning) • e(String, String) (error) 依其重要程度（優先度）區分 }常⽤用
- 52. 使⽤用 LogCat 監看除錯訊息 依照Priority 篩選過濾
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- 56. 應⽤用程式沒有回應 • 程式執⾏行超過五秒，UI 仍未能與使⽤用者互動 •常發⽣生在： • 處理複雜的演算法 • 等待網路傳輸資料 Application Not Responding (ANR)
- 57. 處理 ANR 的⽅方法 •Thread / Runnable • AsyncTask • Handler 多執⾏行緒程式設計（Multithreading）
- 58. AsyncTask 範例 1. privateclass MyTask extends AsyncTaskVoid, Void, Void { 2. protected Long doInBackground(...) { 3. ... 4. } 5. } KeepingYour App Responsive http://developer.android.com/training/articles/perf-anr.html
- 59. 程式實作 • 修改 res/layout/activity_main.xml •加⼊入 Button 「顯⽰示地圖」 • 加⼊入 ImageView 在畫⾯面下⽅方
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- 62. findViewById public class MainActivityextends Activity { private RadioGroup radioGroup1; private TextView textView1; private ImageView imageView1; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); radioGroup1 = (RadioGroup) this.findViewById(R.id.radioGroup1); textView1 = (TextView) this.findViewById(R.id.textView1); imageView1 = (ImageView) this.findViewById(R.id.imageView1); }
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- 65. 實作 showMap ⽅方法 publicvoid showMap(View view) { switch (radioGroup1.getCheckedRadioButtonId()) { case R.id.radioButton1: //... break; } }
- 66. lat 與 lng變數 Double lat = null, lng = null; switch (radioGroup1.getCheckedRadioButtonId()) { case R.id.radioButton1: lat = 22.660; lng = 120.350; break; } if (lat != null lng != null) { //... }
- 67. AsyncTask 實作 if (lat!= null lng != null) { String url = ...; new AsyncTaskString, Void, Drawable() { @Override protected Drawable doInBackground(String... params) { try { InputStream is = new URL(params[0]).openStream(); return Drawable.createFromStream(is, src); } catch (Exception ex) { ex.printStackTrace(); } return null; } @Override protected void onPostExecute(Drawable result) { if (result != null) { imageView1.setImageDrawable(result); } super.onPostExecute(result); } }.execute(url); }
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- 70. showWeather ⽅方法實作 public voidshowWeather(View view) { Double lat = null, lng = null; switch (radioGroup1.getCheckedRadioButtonId()) { case R.id.radioButton1: lat = 22.660; lng = 120.350; break; case R.id.radioButton2: lat = 22.629; lng = 120.262; break; } }
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- 73. OpenWeatherMap Web Services APIAndroidApp HTTP Request Data Response XML, JSON, HTML, …
- 74. AsyncTask 實作 if (lat!= null lng != null) { String url = ...; new AsyncTaskString, Void, String() { @Override protected String doInBackground(String... params) { //... } @Override protected void onPostExecute(String json) { //... } }.execute(url); }
- 75. 存取 HTTP WebServices protected String doInBackground(String... params) { try { BufferedReader reader = new BufferedReader( new InputStreamReader(new URL(params[0]).openStream())); String json = reader.readLine(); reader.close(); return json; } catch (Exception ex) { ex.printStackTrace(); } return null; }
- 76. 解析 JSON 資料 protectedvoid onPostExecute(String json) { if (json != null) { try { JSONObject jsonObject = new JSONObject(json); Double temp = jsonObject.getJSONObject(main).getDouble(temp); textView1.setText(temp + ℃); } catch (Exception ex) { ex.printStackTrace(); } } super.onPostExecute(json); }
- 77. 2. 點擊「查詢天氣」 1. 選擇景點 3.顯⽰示地區氣溫
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- 81. MainActivity public class MainActivityextends Activity { EditText editText1; WebView webView1; Button button1; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); editText1 = (EditText) this.findViewById(R.id.editText1); webView1 = (WebView) this.findViewById(R.id.webView1); button1 = (Button) this.findViewById(R.id.button1); }
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- 83. WebView 設定 //設定只⽤用 WebView開啟網址 webView1.setWebViewClient(new WebViewClient()); //打開 JavaScript webView1.getSettings().setJavaScriptEnabled(true);
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- 85. public void loadWebPage(Viewview) { webView1.loadData(Loading..., text/plain, UTF-8); String keyword = editText1.getText().toString(); try { keyword = URLEncoder.encode(keyword, UTF-8); } catch (UnsupportedEncodingException e) { // TODO Auto-generated catch block e.printStackTrace(); } String url = http://ajax.googleapis.com/ajax/services/search/web?v=1.0q= + keyword; new AsyncTaskString, Void, String() { @Override protected String doInBackground(String... params) { return null; } @Override protected void onPostExecute(String json) { } }.execute(url); }
- 86. doInBackground @Override protected String doInBackground(String...params) { try { InputStream stream = new URL(params[0]).openStream(); InputStreamReader isr = new InputStreamReader(stream, UTF-8); BufferedReader reader = new BufferedReader(isr); String json = reader.readLine(); return json; } catch (Exception ex) { ex.printStackTrace(); } return null; }
- 87. onPostExecute @Override protected void onPostExecute(Stringjson) { if (json != null) { try { JSONObject jsonObject = new JSONObject(json); JSONArray results = jsonObject.getJSONObject(responseData).getJSONArray(results); if (results.length() 0) { String url = results.getJSONObject(0).getString(url); webView1.loadUrl(url); } else { webView1.loadData(Not found..., text/plain, UTF-8); } } catch (Exception ex) { ex.printStackTrace(); } } }
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- 92. 2D 繪圖 setContentView(new View(this){ @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); Paint paint = new Paint(); paint.setStyle(Paint.Style.FILL); paint.setColor(Color.WHITE); canvas.drawPaint(paint); paint.setColor(Color.GREEN); canvas.drawCircle(100, 100, 20, paint); } });