如何显示X秒随机图像，一旦活动是第一次提出了？ [英] How to display a random image for x second once the activity is first brought up?
问题描述
我想显示一个随机图像5秒（我有3图像）时，我的主要活动将启动。 （这是一种教程如何使用我的应用程序和一些广告）。但我只是想每天一次显示它。我需要正确的使用共享preferences？这是做的最好的办法，是吗？所以，我发现这一点：
I'm trying to display a random image for 5 seconds (I've got 3 images) when my main activity is launched. (It's a kind of tutorial how to use my app and some advertisement). But I just want to display it once a day. I need to use SharedPreferences right? It's the best approach to do it, is it? So I found this:
ImageView imgView = new ImageView(this);
Random rand = new Random();
int rndInt = rand.nextInt(n) + 1; // n = the number of images, that start at idx 1
String imgName = "img" + rndInt;
int id = getResources().getIdentifier(imgName, "drawable", getPackageName());
imgView.setImageResource(id);
要显示一个随机图像。而这个：
To display a random image. And this:
public class mActivity extends Activity {
@Overrride
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setContentView(R.id.layout);
// Get current version of the app
PackageInfo packageInfo = this.getPackageManager()
.getPackageInfo(getPackageName(), 0);
int version = packageInfo.versionCode;
SharedPreferences sharedPreferences = this.getPreferences(MODE_PRIVATE);
boolean shown = sharedPreferences.getBoolean("shown_" + version, false);
ImageView imageView = (ImageView) this.findViewById(R.id.newFeature);
if(!shown) {
imageView.setVisibility(View.VISIBLE);
// "New feature" has been shown, then store the value in preferences
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.put("shown_" + version, true);
editor.commit();
} else
imageView.setVisibility(View.GONE);
}
要显示一旦应用程序更新应用程序的当前版本。我试着去适应那些codeS为我的应用程序，但我失败了。我还需要图像具有要显示只有5秒，自动关闭。
To show once an app is updated the current version of the app. I tried to adapt those codes for my app but I failed. I also need that the image has to be displayed just 5 seconds and close automatically.
嘿，这又是我。我现在得到这个code和它完美的作品：
Hey it's me again. I got this code now and it works perfectly:
boolean firstboot = getSharedPreferences("BOOT_PREF",MODE_PRIVATE).getBoolean("firstboot", true);
getSharedPreferences("BOOT_PREF",MODE_PRIVATE).edit().
putBoolean("firstboot", true).commit();
if(firstboot){
Intent webBrowser = new Intent(getApplicationContext(), WebBrowser.class);
// dismiss it after 5 seconds
webBrowser.putExtra("url", "http://sce.jelocalise.fr/mobile/ajax/interstitiel.php");
startActivity(webBrowser);
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
Intent MyIntent = new Intent(getApplicationContext(), Home.class);
startActivity(MyIntent);
}
}
}, 5000);
getSharedPreferences("BOOT_PREF",MODE_PRIVATE).edit().
putBoolean("firstboot", false).commit();
}
我现在想什么：有我的WebView取消按钮，当我点击它，它完成了web浏览器的活动。问题是，当我点击取消按钮处理程序不停止，并在5秒后重新加载主页活动（这是正常的，我知道）。我只想说取消按钮杀死了处理程序。我试过handler.removeCallbacks方法，但我并没有真正了解它是如何工作的。
What I want now: there is a cancel button on my webview and when I click on it, it finishes the webBrowser activity. The problem is when I click on the cancel button the handler doesn't stop, and after 5 seconds it reloads the Home activity (which is normal I know). I just want that the cancel button kills the handler. I've tried handler.removeCallbacks method but I didn't really understand how it works.
推荐答案
好了，你要显示的图像为5秒，你不想往往比每天一次来显示图像？这意味着，你需要保持您上次显示图像的轨道，共享preferences很适合这一点。我建议你使用自定义AlertDialog来显示图像。它看起来不错，它会暗淡了在后台活动。我建议你使用一个计时器，一个TimerTask的一段时间后，关闭该对话框。这里有一个例子：
Ok, so you want to show an image for 5 seconds and you don't want to show the image more often than once a day? This implies that you need to keep track of when you showed the image last, SharedPreferences works well for this. I suggest that you use a custom AlertDialog to show the image. It will look nice and it will dim out the activity in the background. And I'd recommend the use of a Timer and a TimerTask to dismiss the dialog after a certain period of time. Here's an example:
/**
* imageIds is an array of drawable resource id to chose from
* Put the images you like to display in res/drawable-nodpi (if you
* prefer to provide images for several dpi_bracket you put them in
* res/drawable-mpdi, drawable-hdpi etc).
* Add each of their resource ids to the array. In the example
* below I assume there's four images named myimage1.png (or jpg),
* myimage2, myimage3 and myimage4.
*/
@Overrride
public void onCreate(Bundle savedInstanceState) {
final int[] imageIds = { R.drawable.myimage1, R.drawable.myimage2, R.drawable.myimage3, R.drawable.myimage4 };
final int id = new Random().nextInt(imageIds.length - 1);
showImageDialog(id, 24 * 60 * 60 * 1000, 5000);
}
/**
* Show an image in a dialog for a certain amount of time before automatically dismissing it
* The image will be shown no more frequently than a specified interval
* @param drawableId A resource id for a drawable to show
* @param minTime Minimum time in millis that has to pass since the last time an aimage was shown
* @param delayBeforeDismiss Time in millis before dismissing the dialog
*
*/
private void showImageDialog(int drawableId, long minTime, long delayBeforeDismiss) {
final SharedPreferences prefs = getPreferences(MODE_PRIVATE);
// make sure we don't show image too often
if((System.currentTimeMillis() - minTime) < prefs.getLong("TIMESTAMP", 0)) {
return;
}
// update timestamp
prefs.edit().putLong("TIMESTAMP", System.currentTimeMillis()).commit();
// create a custom alert dialog with an imageview as it's only content
ImageView iv = new ImageView(this);
iv.setBackgroundDrawable(getResources().getDrawable(drawableId));
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setView(iv);
final AlertDialog dialog = builder.create();
dialog.show();
// dismiss it after 5 seconds
new Timer().schedule(new TimerTask() {
@Override
public void run() {
dialog.dismiss();
}
}, delayBeforeDismiss);
}
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