One of the Oschina Android client source code learning

Today, we'll focus on two functions.

(1) Double-click the back key to exit the program

(2) close to the perfect exit program

(1)

In very many applications there is a function, that is, click the Back button, then prompt you to click the Back button to exit the program.

have been very curious about how this is achieved, today is just the source of the security in the open source code stripped down, so here to study this very easy function.

public class Doubleclickexithelper {private Final Activity mactivity;private boolean isonkeybacking;private Handler Mhandler;private Toast mbacktoast;public doubleclickexithelper (activity activity) {mactivity = Activity;mhandler = new Handler (Looper.getmainlooper ());//Key point}/** * Activity OnKeyDown Event * */public boolean onKeyDown (int keycode, keyevent Event) {if (keycode! = Keyevent.keycode_back) {return false;} if (isonkeybacking) {mhandler.removecallbacks (onbacktimerunnable); if (mbacktoast! = null) {Mbacktoast.cancel ();} Exit Appmanager.getappmanager (). AppExit (mactivity); return true;} else {//isonkeybacking default value is False. So first click into here//java Boolean is the default value of isonkeybacking = true;if (Mbacktoast = = null) {Mbacktoast = Toast.maketext (mactivity, R.string.back_exit_tips, 2000);} Mbacktoast.show (); mhandler.postdelayed (onbacktimerunnable, +); return true;}} Private Runnable onbacktimerunnable = new Runnable () {@Overridepublic void run () {isonkeybacking = False;if (mbacktoast! = NULL) {//android with Toast.cancel () method to optimize the display of toast content//details to be able to Baidu Mbacktoast.cancel ();}}; 

Simple to understand is to listen to the return key. The first time I press it. With mbacktoast. Show (); displays a hint text.

Here is "Press again to exit open source China". Duration 2000ms.

Use this at the same time. mhandler. postdelayed an asynchronous operation is turned on, and the delay time is2000ms . Which means the Runnableonbacktimerunnable when the text disappears. It will call run . method. isonkeybacking value to false . Which means2sthen your second click does not work. Everything back to the original point.

and suppose you once in 2s Click again inside the word.

AppManager. Getappmanager (). AppExit (mactivity);

The program is out.

When it's used?

< Span style= "font-size:12pt" > mdoubleclickexithelper = New doubleclickexithelper ( this

To support this double exit activity , distribute the onkeydown event down:

/** * Listener return--whether to exit the program */public boolean onKeyDown (int keycode, KeyEvent event) {Boolean flag = true;if (keycode = = keyevent.ke Ycode_back) {//Whether exit applies return Mdoubleclickexithelper.onkeydown (KeyCode, event);} else if (keycode = = Keyevent.keycode_ MENU) {//Show Shortcut Bar & Infer if login uihelper.showsettingloginorlogout (main.this,mgrid.getquickaction (0)); Mgrid.show ( Fbsetting, True);} else if (keycode = = Keyevent.keycode_search) {//Show search page Uihelper.showsearch (main.this);} else {flag = Super.onkeydown ( KeyCode, event);} return flag;}

This allows the entire function to be realized.

(2) close to the perfect exit program

Next, analyze the open source Chinese client this exit function. That above

appmanager. GetAppManager (). AppExit ( mactivity implementation of this function

private static stack<activity> activitystack;/** * Exit application */public void AppExit (context context) {try {finishallact Ivity (); Activitymanager activitymgr= (Activitymanager) Context.getsystemservice (context.activity_service);// android2.2 should be followed by killbackgroundprocesses (String packagename) activitymgr.restartpackage (Context.getpackagename ()); System.exit (0);}  catch (Exception e) {}}/** * ends all activity */public void finishallactivity () {for (int i = 0, size = activitystack.size (); I < size; i++) {            if (null! = Activitystack.get (i)) {            activitystack.get (i). Finish ();            }    } Activitystack.clear ();}

stick out the key source code everyone is clear. There's a store app .AllActivity the stackactivitystack ;

of course Join Activity The source code is not posted.

when the application exits, it's just a walk through the stack . . Then call Finish () . and finally callsystem.exit (0);Elegant. Completely end the whole program.

One of the Oschina Android client source code learning