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Web Programming 網際網路程式設計

Learn how to create a web application using WebView and Android Intent. This tutorial covers basic app programming, WYSIWYG form design, and the Android activity lifecycle.

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Web Programming 網際網路程式設計

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  1. Web Programming網際網路程式設計 Web Programming 網際網路程式設計

  2. App Programming手機程式設計 Web Programming 網際網路程式設計

  3. Again, we have only two hours Web Programming 網際網路程式設計

  4. Basic idea • There is a browser component, WebView • you could imagine that every new platform will have such a component • When users open our app, we show them a full-screen browser and load our homepage immediately • remember to hide the address bar • The remaining things are HTML, CSS, JavaScript and, if needed, CGI Web Programming 網際網路程式設計

  5. Today we will show you • A Web App Generator, wag • A demo to introduce the development environment, Eclipse • Basic app (windows) programming • WYSIWYG form design, event driven… • Basic Android app programming • Activity (a page in an app), especially its life cycle • Intent (information from an Activity to another) • Techniques needed for our basic idea • WebView • bind JS code to Android code Web Programming 網際網路程式設計

  6. Demo Web Programming 網際網路程式設計

  7. WYSIWYG form design Web Programming 網際網路程式設計 http://www.techotopia.com/index.php/Designing_Forms_in_Visual_Studio

  8. Event driven http://www.techotopia.com/index.php/Understanding_Visual_Basic_Events

  9. Android life cycle • LifeCycle • 手機的特性是能隨時離開正在使用的程式，切換到接電話、接收簡訊模式，而且在回來時能看到一樣的內容 • 使用者已經習慣了多工(Multi-Task)的作業系統 • 同時執行多個程式需要更多記憶體，而手機裡的記憶體是相當有限的。當同時執行的程式過多，或是關閉的程式沒有正確釋放記憶體，系統就會越來越慢。為了解決這個問題，Android 引入了一個新的機制：生命週期 Web Programming 網際網路程式設計

  10. This is not new http://en.wikipedia.org/wiki/Process_state

  11. http://vardhan-justlikethat.blogspot.com/2012/03/developer-view-ios-view-controller.htmlhttp://vardhan-justlikethat.blogspot.com/2012/03/developer-view-ios-view-controller.html

  12. about the life cycle Web Programming 網際網路程式設計

  13. What actions cause onPause()? Web Programming 網際網路程式設計

  14. More detailed one http://rupaknepali.com.np/activity-life-cycle-in-the-android-application-development/1474.php

  15. Intent • AndroidIntent • Intent 是一個動作與內容的集合。Intent 像是一串網址，傳送「意圖」給其他 Activity 來處理網址中所指定的動作跟內容。Android 使用 Intent 來完成在螢幕間切換的動作 • 從另一個角度來說，Intent 包含 Activity 間切換所需的動作、分類、傳送資料等訊息，就像是 Activity 之間的宅急便一樣 • Intent intent = new Intent();intent.setClass(foo.this, bar.class); // from foo to bar// retrieve and pack variablesBundle bundle = new Bundle();bundle.putString("FOO_VAR1", foo_var1.getText().toString());bundle.putString("FOO_VAR2", foo_var2.getText().toString());intent.putExtras(bundle);startActivity(intent); // start another activity Web Programming 網際網路程式設計

  16. WebView • android开发中WebView的使用(附完整程序) • WebView相當於一個迷你的瀏覽器，採用 Webkit核心，因此完美支援 HTML, CSS 以及 JavaScript 等。有時可以把UI 甚至數據處理都交给 WebView，配合 PHP 等伺服器端程式，這樣 Android 開發就變成了網頁開發 • 上面網址中提供一個 WebView的簡單例子，如果把所有功能都交给伺服器端處理，你只要寫好網頁，把URL 填上，再編譯，就是一个新app。 • WebView | Android Developers • Building Web Apps in WebView | Android Developers Web Programming 網際網路程式設計

  17. WebView code snippet Get the view object. • wv = (WebView) findViewById(R.id.wv);wv.getSettings().setJavaScriptEnabled(true);wv.setScrollBarStyle(0);wv.setWebChromeClient(new WebChromeClient(){ public booleanonJsAlert(…) { return super.onJsAlert(…); } public void onProgressChanged(…){ if ( 100 == progress ) { … }super.onProgressChanged(…); }}); Web Programming 網際網路程式設計

  18. WebView code snippet Enable JavaScript and hide the scroll bar. • wv = (WebView) findViewById(R.id.wv);wv.getSettings().setJavaScriptEnabled(true);wv.setScrollBarStyle(0);wv.setWebChromeClient(new WebChromeClient(){ public booleanonJsAlert(…) { return super.onJsAlert(…); } public void onProgressChanged(…){ if ( 100 == progress ) { … }super.onProgressChanged(…); }}); Web Programming 網際網路程式設計

  19. WebView code snippet • wv = (WebView) findViewById(R.id.wv);wv.getSettings().setJavaScriptEnabled(true);wv.setScrollBarStyle(0);wv.setWebChromeClient(new WebChromeClient(){ public booleanonJsAlert(…) { return super.onJsAlert(…); } public void onProgressChanged(…){ if ( 100 == progress ) { … }super.onProgressChanged(…); }}); WebChromeClient handles dialogs, progress… Web Programming 網際網路程式設計

  20. about the code snippet Web Programming 網際網路程式設計

  21. What/why R.id.wv super call super.xx() return Web Programming 網際網路程式設計

  22. Layout • Arrange widgets/controls/components • FrameLayout, LinearLayout, RelativeLayout, AbsoluteLayoutand TableLayout • Layout classes are also widgets • Android的Layout整理 • [新手完全手冊] Hello Android Layout • User Interface | Android Developers Web Programming 網際網路程式設計

  23. It was specified in the res/layout/xxx.xml Web Programming 網際網路程式設計 http://www.holisticware.com/HolisticWare/Know-How/development/integrated-development-environments-ides/eclipse.aspx

  24. Activity-WebView communication • Building Web Apps in WebView • Activity can change the URL of WebView to pass data • The difficult part is how to retrieve data from WebView • call addJavascriptInterface() and pass it a class instance to bind an interface name that your JS can call to access the class • Once the communication between Activity and WebView is connected, you are actually developing an web app. App (Activity) A full-screen WebView Web server CGI programs Java HTML, CSS and JavaScript Perl, PHP or anything you like Web Programming 網際網路程式設計

  25. Communication code snippet • Java call JavaScript • function java_call_js() { … } • wv.loadUrl("javascript:java_call_js()"); • JavaScript call Java • wv.getSettings().setJavaScriptEnabled(true);public class WebAppInterface { public void js_call_java() { … }}wv.addJavascriptInterface( new WebAppInterface(), "android"); • window.android.js_call_java(); In JavaScript, declare a function. Web Programming 網際網路程式設計

  26. Communication code snippet • Java call JavaScript • function java_call_js() { … } • wv.loadUrl("javascript:java_call_js()"); • JavaScript call Java • wv.getSettings().setJavaScriptEnabled(true);public class WebAppInterface { public void js_call_java() { … }}wv.addJavascriptInterface( new WebAppInterface(), "android"); • window.android.js_call_java(); In Java, change the URL to execute any JS code. This is a common behavior for all browsers. So actually you don’t need to design new JS functions intentionally. Web Programming 網際網路程式設計

  27. Communication code snippet • Java call JavaScript • function java_call_js() { … } • wv.loadUrl("javascript:java_call_js()"); • JavaScript call Java • wv.getSettings().setJavaScriptEnabled(true);public class WebAppInterface { public void js_call_java() { … }}wv.addJavascriptInterface( new WebAppInterface(), "android"); • window.android.js_call_java(); In Java, always remember to enable JS. Web Programming 網際網路程式設計

  28. Communication code snippet • Java call JavaScript • function java_call_js() { … } • wv.loadUrl("javascript:java_call_js()"); • JavaScript call Java • wv.getSettings().setJavaScriptEnabled(true);public class WebAppInterface { public void js_call_java() { … }}wv.addJavascriptInterface( new WebAppInterface(), "android"); • window.android.js_call_java(); In Java, bind a new interface with addJavaScriptInterface(). Web Programming 網際網路程式設計

  29. Communication code snippet • Java call JavaScript • function java_call_js() { … } • wv.loadUrl("javascript:java_call_js()"); • JavaScript call Java • wv.getSettings().setJavaScriptEnabled(true);public class WebAppInterface { public void js_call_java() { … }}wv.addJavascriptInterface( new WebAppInterface(), "android"); • window.android.js_call_java(); In JavaScript, the bound interface is actually an object whose member variables/functions are accessible to JS. The object name corresponds to the second parameter of addJavascriptInterface(). Web Programming 網際網路程式設計

  30. Reminders of the environment • https://developer.android.com/sdk/index.html • download the SDK (including Eclipse, ADT plugin, Android SDK…), which needs no installation • http://www.oracle.com/technetwork/java/javase/archive-139210.html • download and install JDK (version 6 is suggested by Google) • Setup Android SDK Manager (API version, Google API…) • Setup Android Virtual Device Manager (resolution, SD Card…) • you can use real phones • This is usually the most painful stage (try and error) when learning a new platform. It can be largely eased if you have a good mentor, or at least a partner to discuss. That’s what this course tries to provide. Web Programming 網際網路程式設計

  31. Step-by-step of the demo • Create an Android Application Project with a Blank Activity or Fullscreen Activity • Add a WebView(in Composite) by editing res/layout/activity_main.xml • change its id (e.g. wv) make it full-screen (via property table or .xml) • Enable required permissions (e.g. internet permission) • AndroidManifest.xml Add Uses Permission  android.permission.INTERNET • Add a new event handler, onCreate(), by editing src/xxx/xxx.java • xxx/xxx is your main activity, which depends on the settings when creating the application • requestWindowFeature(Window.FEATURE_NO_TITLE); // hide the title barWebViewwv= (WebView) findViewById(R.id.wv); // get the WebViewwv.getSettings().setJavaScriptEnabled(true); // enable JavaScriptwv.loadUrl("http://www.google.com"); // load a URLwv.loadUrl("javascript:foo()"); // execute JavaScript • If you want to load a HTML file offline, store it (e.g. index.html) in assets/ • wv.loadUrl("file:///android_asset/index.html"); • Run your application • you will get bin/xxx.apk, put it to a public place to distribute your applicatoin Web Programming 網際網路程式設計

  32. Today’s assignment今天的任務 Web Programming 網際網路程式設計

  33. Create an app • Two options, you may create a very simple app. Another option is to make a mobile version (small screen version) for your site. So that mobile users feel good when browsing your site. • Reference • Android Developers • How To Build A Mobile Website • mobile web - Google 搜尋 • 開發手機版網頁 • Your web site (http://merry.ee.ncku.edu.tw/~xxx/cur/, ex12) will be checked not before 23:59 1/7 (Tue). You may send a report (such as some important modifications) to me in case I did not notice your features. Or, even better, just explain your modifications in the homepage. Web Programming 網際網路程式設計

  34. Appendix附錄 Web Programming 網際網路程式設計

  35. Thread • [Android] 多執行緒-Handler和Thread的關係 • 在 Android 當中，一件事如果做超過 5 秒被系統強制關閉(收到Application not Responsed, ANR)；在 onCreate() 中如果做超過 10 秒就會跳ANR • 所以繁重的事情不能在 onCreate() 裡頭做。解決的辦法就是 thread (執行緒) • Main thread for UI, worker threads for long-time work and use handers to find other threads • Thread | Android Developers • android裡的thread的朋友：Handler Web Programming 網際網路程式設計

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