Calls in JavaScript in Android

Refer to Zhang Yang: 2048-ai program algorithm analysis, and analysis of the Android version of the source code, think that Android calls JavaScript code can be quickly re-use of web codes, improve development efficiency, then the Android and JavaScript call each other to learn and record.

First, what is JS and Android interaction?

The popular point is to use the JS code to call Java code, or use Java code to invoke the JS code. That is, mixed programming.

Second, why use JS to interact with Java code?

1. You can do some JS Web pages do not handle the things themselves. For example, call Android locally on a webpage, send SMS, call the Android phone address Book on a webpage, call a third-party app on a webpage, call some Android localized processing on a webpage (Operation IO, database), etc.

2. JS developers can be implemented in collaboration with Android developers. For example: JS developers to develop JS code for Android developers to call, Android developers do not have to write JS code, you can focus on Andrid development, use the JS when the direct call JS code can be. (and vice versa)

3. The dynamic update of the webpage can be realized. For example, you can use the JS code to call the Java Update data displayed on the Web page to achieve the purpose of dynamically updating the page.

Third, the Android and JS code calls each other

1.Android Terminal code

　　

 Public classMyActivityextendsActivity {PrivateWebView Mywebview; PrivateImageButton IButton; Private BooleanFlag =false; @Overrideprotected voidonCreate (Bundle savedinstancestate) {Super. OnCreate (savedinstancestate);        Setcontentview (r.layout.activity_my); IButton=(ImageButton) Findviewbyid (R.id.imagebutton); Mywebview=NewWebView ( This); Mywebview.getsettings (). setjavascriptenabled (true); //Enable JavaScript Mywebview.addjavascriptinterface ( This, "Android"); //Bind JavaScript with Android code Mywebview.loadurl ("File:///android_asset/index.html");//load Web, that is, JS portal. JS Call Android //ibutton.setimagedrawable (Getresources (). getdrawable (R.drawable.eg_bulbon));} @JavascriptInterface // if Target is greater than or equal to API 17, you need to add the following annotations
     Public voidOnjsrun (Booleanflag) {       if(flag) {LOG.E ("Ai~~~~~", "true"); Handler.sendemptymessage (1); }Else{LOG.E ("Ai~~~~~~~", "false"); Handler.sendemptymessage (2); }    }     PublicHandler Handler =NewHandler () { Public voidhandlemessage (Message msg) {Switch(msg.what) { Case1: LOG.E ("111111111", "iscalled");                    Ibutton.setbackground (Getresources (). getdrawable (R.drawable.eg_bulbon)); Try{thread.currentthread (); Thread.Sleep (200); } Catch(interruptedexception e) {e.printstacktrace (); } mywebview.loadurl ("Javascript:changeimage (False)"); //android Direct JS function  Break;  Case2: LOG.E ("2222222222222", "iscalled");                    Ibutton.setbackground (Getresources (). getdrawable (R.drawable.eg_bulboff)); Try{thread.currentthread (); Thread.Sleep (200); } Catch(interruptedexception e) {e.printstacktrace (); } mywebview.loadurl ("Javascript:changeimage (True)");  Break; default:                     Break;    }        }    }; @JavascriptInterface // if Target is greater than or equal to API 17, you need to add the following annotations

     Public voidDebug (String msg) {LOG.E ("AI", MSG); }

Web-side code:

<! DOCTYPE html> Changeimage (true); </script><p> tap the light bulb to light or turn off this lamp. </p></body>
JS Code
function changeimage (flag) {Android.debug ("The JS call is run"//js calls the Android function android.onjsrun (flag);}
Operation Result: 300ms,ui change.